1. Study suggests inherited IQ can increase in early childhood

    February 13, 2018 by Ashley

    From the Rutgers University press release:

    When it comes to intelligence, environment and education matter — more than we think.

    Those are the findings of Rutgers University psychologists Louis Matzel and Bruno Sauce, based on an integrative review of recent studies on the nature of human intelligence. Their study is published in the December issue of the Psychological Bulletin, a journal of the American Psychological Association.

    “Genetic influences don’t run the show, nor do environmental effects. It’s the genetic-environmental interplay that is the ringmaster,” said Matzel, a professor of psychology in the School of Arts and Sciences at Rutgers-New Brunswick. Sauce is a graduate student in Rutgers’ School of Graduate Studies.

    The study, the researchers say, has significant implications for the way we educate children, whose inherited IQ can increase, especially during early childhood, with the right kind of stimulation and attention.

    “We educate children the hard way in this country,” Matzel said. “We go to impoverished high schools and try to remediate kids, which is a perfectly good thing to do. But it’s often too late; the time to reach those kids is when they start school, while their intelligence is most malleable.”

    Scientists measure the heritability of traits on a scale of 0.0 to 1.0. Eye color has a heritability score of .99, meaning that it’s highly genetic. Intelligence typically rates at .8, Matzel and Sauce said, which means that it, too, is very heritable. However, Matzel and Sauce believe people often underestimate the role of environment.

    “Through interactions and correlations with the environment, genetic influences can be expressed in wildly different ways, and environmental influences are much more powerful than many scientists believe,” Sauce said.

    The researchers said the heritability of IQ can be as low as .3 in young children, which leaves plenty of room for changes in intelligence. But school systems often ignore this opportunity, they believe, focusing on increasing rote knowledge at the expense of critical thinking. Intervention programs then often fail to create lasting changes to children’s environment.

    Consider children who take part in Head Start, the federal program that provides low-income children with comprehensive early childhood education, nutrition and parent-involvement services. Matzel said those children’s IQ scores increase significantly while they’re part of the program, but frequently regress after they leave it — a common criticism of these programs. That, he said, is because the stimulation and encouragement received in Head Start is missing when the child returns to their more restrictive environment.

    Or consider identical twins separated at birth. If their IQs are nearly identical, and they have equal opportunities, they will be equally smart as adults. However, if one is deprived of opportunities, their cognitive abilities will diverge, Matzel said. This highlights the important role that environmental opportunity plays in the establishment of an individual’s intelligence.

    While twins may have the same basic mental equipment with which to face the world, the twin raised in the better environment can thrive while his sibling is thwarted. “The environment is the critical tool that allows our genetic equipment to prosper,” Matzel said.


  2. New brain mapping technique highlights relationship between connectivity and IQ

    January 17, 2018 by Ashley

    From the University of Cambridge press release:

    A new and relatively simple technique for mapping the wiring of the brain has shown a correlation between how well connected an individual’s brain regions are and their intelligence, say researchers at the University of Cambridge.

    In recent years, there has been a concerted effort among scientists to map the connections in the brain — the so-called ‘connectome‘ — and to understand how this relates to human behaviours, such as intelligence and mental health disorders.

    Now, in research published in the journal Neuron, an international team led by scientists at the University of Cambridge and the National Institutes of Health (NIH), USA, has shown that it is possible to build up a map of the connectome by analysing conventional brain scans taken using a magnetic resonance imaging (MRI) scanner.

    The team compared the brains of 296 typically-developing adolescent volunteers. Their results were then validated in a cohort of a further 124 volunteers. The team used a conventional 3T MRI scanner, where 3T represents the strength of the magnetic field; however, Cambridge has recently installed a much more powerful Siemens 7T Terra MRI scanner, which should allow this technique to give an even more precise mapping of the human brain.

    A typical MRI scan will provide a single image of the brain, from which it is possible to calculate multiple structural features of the brain. This means that every region of the brain can be described using as many as ten different characteristics. The researchers showed that if two regions have similar profiles, then they are described as having ‘morphometric similarity’ and it can be assumed that they are a connected network. They verified this assumption using publically-available MRI data on a cohort of 31 juvenile rhesus macaque monkeys to compare to ‘gold-standard’ connectivity estimates in that species.

    Using these morphometric similarity networks (MSNs), the researchers were able to build up a map showing how well connected the ‘hubs’ — the major connection points between different regions of the brain network — were. They found a link between the connectivity in the MSNs in brain regions linked to higher order functions — such as problem solving and language — and intelligence.

    “We saw a clear link between the ‘hubbiness’ of higher-order brain regions — in other words, how densely connected they were to the rest of the network — and an individual’s IQ,” explains PhD candidate Jakob Seidlitz at the University of Cambridge and NIH. “This makes sense if you think of the hubs as enabling the flow of information around the brain — the stronger the connections, the better the brain is at processing information.”

    While IQ varied across the participants, the MSNs accounted for around 40% of this variation — it is possible that higher-resolution multi-modal data provided by a 7T scanner may be able to account for an even greater proportion of the individual variation, says the researchers.

    “What this doesn’t tell us, though, is where exactly this variation comes from,” adds Seidlitz. “What makes some brains more connected than others — is it down to their genetics or their educational upbringing, for example? And how do these connections strengthen or weaken across development?”

    “This could take us closer to being able to get an idea of intelligence from brain scans, rather than having to rely on IQ tests,” says Professor Ed Bullmore, Head of Psychiatry at Cambridge. “Our new mapping technique could also help us understand how the symptoms of mental health disorders such as anxiety and depression or even schizophrenia arise from differences in connectivity within the brain.”

     


  3. Study suggests human-like virtual assistants can deter help-seeking

    January 15, 2018 by Ashley

    From the Association for Psychological Science press release:

    Virtual assistants have become increasingly sophisticated — and more humanlike — since the days when Clippy asked if you needed help with your document. These assistants are intended to make programs and apps easier to use, but research published in Psychological Science suggests that humanlike virtual assistants may actually deter some people from seeking help on tasks that are supposed to measure achievementPsychological Science is a journal of the Association for Psychological Science.

    “We demonstrate that anthropomorphic features may not prove beneficial in online learning settings, especially among individuals who believe their abilities are fixed and who thus worry about presenting themselves as incompetent to others,” says psychological scientist and study author Daeun Park of Chungbuk National University. “Our results reveal that participants who saw intelligence as fixed were less likely to seek help, even at the cost of lower performance.”

    Previous research has shown that people are inclined to see computerized systems as social beings with only a couple social cues. This social dynamic can make the systems seem less intimidating and more user-friendly, but Park and coauthors Sara Kim and Ke Zhang wondered whether that would be true in a context where performance matters, such as with online learning platforms.

    “Online learning is an increasingly popular tool across most levels of education and most computer-based learning environments offer various forms of help, such as a tutoring system that provides context-specific help,” says Park. “Often, these help systems adopt humanlike features; however, the effects of these kinds of help systems have never been tested.”

    In one online study, the researchers had 187 participants complete a task that supposedly measured intelligence. In the task, participants saw a group of three words (e.g., room, blood, salts) and were supposed to come up with a fourth word that related to all three (e.g., bath). On the more difficult problems, they automatically received a hint from an onscreen computer icon — some participants saw a computer “helper” with humanlike features including a face and speech bubble, whereas others saw a helper that looked like a regular computer.

    Participants reported greater embarrassment and concerns about self-image when seeking help from the anthropomorphized computer versus the regular computer, but only if they believed that intelligence is a fixed, not malleable trait.

    The findings indicated that a couple of anthropomorphic cues are sufficient to elicit concern about seeking help, at least for some individuals. Park and colleagues decided to test this directly in a second experiment with 171 university students.

    In the experiment, the researchers manipulated how the participants thought about intelligence by having them read made-up science articles that highlighted either the stability or the malleability of intelligence. The participants completed the same kind of word problems as in the first study — this time, they freely chose whether to receive a hint from the computer “helper.”

    The results showed that students who were led to think about intelligence as fixed were less likely to use the hints when the helper had humanlike features than when it didn’t. More importantly, they also answered more questions incorrectly. Those who were led to think about intelligence as a malleable trait showed no differences.

    These findings could have implications for our performance using online learning platforms, the researchers conclude:

    “Educators and program designers should pay special attention to unintended meanings that arise from humanlike features embedded online learning features,” says Park. “Furthermore, when purchasing educational software, we recommend parents review not only the contents but also the way the content is delivered.”

     


  4. Study suggests smart people have better connected brains

    December 4, 2017 by Ashley

    From the Goethe University Frankfurt press release:

    Differences in intelligence have so far mostly been attributed to differences in specific brain regions. However, are smart people’s brains also wired differently to those of less intelligent persons? A new study supports this assumption. In intelligent persons, certain brain regions are more strongly involved in the flow of information between brain regions, while other brain regions are less engaged.

    Understanding the foundations of human thought is fascinating for scientists and laypersons alike. Differences in cognitive abilities — and the resulting differences for example in academic success and professional careers — are attributed to a considerable degree to individual differences in intelligence. A study just published in Scientific Reports shows that these differences go hand in hand with differences in the patterns of integration among functional modules of the brain. Kirsten Hilger, Christian Fiebach and Ulrike Basten from the Department of Psychology at Goethe University Frankfurt combined functional MRI brain scans from over 300 persons with modern graph theoretical network analysis methods to investigate the neurobiological basis of human intelligence.

    Already in 2015, the same research group published a meta-study in the journal Intelligence, in which they identified brain regions — among them the prefrontal cortex — activation changes of which are reliably associated with individual differences in intelligence. Until recently, however, it was not possible to examine how such ‘intelligence regions’ in the human brain are functionally interconnected.

    Earlier this year, the research team reported that in more intelligent persons two brain regions involved in the cognitive processing of task-relevant information (i.e., the anterior insula and the anterior cingulate cortex) are connected more efficiently to the rest of the brain (2017, Intelligence). Another brain region, the junction area between temporal and parietal cortex that has been related to the shielding of thoughts against irrelevant information, is less strongly connected to the rest of the brain network. “The different topological embedding of these regions into the brain network could make it easier for smarter persons to differentiate between important and irrelevant information — which would be advantageous for many cognitive challenges,” proposes Ulrike Basten, the study’s principle investigator.

    In their current study, the researchers take into account that the brain is functionally organized into modules. “This is similar to a social network which consists of multiple sub-networks (e.g., families or circles of friends). Within these sub-networks or modules, the members of one family are more strongly interconnected than they are with people from other families or circles of friends. Our brain is functionally organized in a very similar way: There are sub-networks of brain regions — modules — that are more strongly interconnected among themselves while they have weaker connections to brain regions from other modules. In our study, we examined whether the role of specific brain regions for communication within and among brain modules varies with individual differences in intelligence, i.e., whether a specific brain region supports the information exchange within their own ‘family’ more than information exchange with other ‘families’, and how this relates to individual differences in intelligence.”

    The study shows that in more intelligent persons certain brain regions are clearly more strongly involved in the exchange of information between different sub-networks of the brain in order for important information to be communicated quickly and efficiently. On the other hand, the research team also identified brain regions that are more strongly ‘de-coupled’ from the rest of the network in more intelligent people. This may result in better protection against distracting and irrelevant inputs. “We assume that network properties we have found in more intelligent persons help us to focus mentally and to ignore or suppress irrelevant, potentially distracting inputs,” says Basten. The causes of these associations remain an open question at present. “It is possible that due to their biological predispositions, some individuals develop brain networks that favor intelligent behaviors or more challenging cognitive tasks. However, it is equally as likely that the frequent use of the brain for cognitively challenging tasks may positively influence the development of brain networks. Given what we currently know about intelligence, an interplay of both processes seems most likely.”


  5. Theory: Flexibility is at the heart of human intelligence

    by Ashley

    From the University of Illinois at Urbana-Champaign press release:

    Centuries of study have yielded many theories about how the brain gives rise to human intelligence. Some neuroscientists think intelligence springs from a single region or neural network. Others argue that metabolism or the efficiency with which brain cells make use of essential resources are key.

    A new theory, published in the journal Trends in Cognitive Sciences, makes the case that the brain’s dynamic properties — how it is wired but also how that wiring shifts in response to changing intellectual demands — are the best predictors of intelligence in the human brain.

    “When we say that someone is smart, we understand intuitively what that means,” said University of Illinois psychology professor Aron Barbey, the author of the new paper. “Usually, we’re referring to how good they are at making decisions and solving particular types of problems. But recently in neuroscience, there’s been a focus on understanding in biological terms how general intelligence arises.” That requires studying the structural and functional characteristics of the brain.

    Scientists have long understood that the brain is modular, with different regions supporting specific abilities, Barbey said.

    “For example, brain regions within the occipital lobe at the back of the brain are known to processes visual information,” he said. But interpreting what one sees requires the integration of information from other brain modules.

    “To identify an object, we also must classify it. That doesn’t depend only on vision. It also requires conceptual knowledge and other aspects of information processing, which are supported by other brain regions,” he said. “And as the number of modules increases, the type of information represented in the brain becomes increasingly abstract and general.”

    Scientists have struggled to understand how the brain organizes itself and have tried to identify a structure or region that performs that function.

    “The prefrontal cortex, a structure at the front of the brain, for example, has expanded dramatically over the course of human evolution,” Barbey said. Because this brain region is known to support several higher-order functions such as planning and organizing one’s behavior, scientists have suggested that the prefrontal cortex drives general intelligence.

    “But really, the entire brain — its global architecture and the interactions among lower- and higher-level mechanisms — is required for general intelligence,” Barbey said.

    Brain modules provide the basic building blocks from which larger, “intrinsic connectivity networks” are constructed, Barbey said. Each network includes multiple brain structures that are activated together when a person engages a particular cognitive skill.

    “For example, the frontoparietal network is activated when attention is focused on external cues, the salience network is engaged when attention is directed to relevant events, and the default mode network is recruited when attention is focused internally,” he said.

    Neural networks are made up of two types of connections that are believed to support two types of information processing, Barbey said.

    “There are the pathways that encode prior knowledge and experience, which we call ‘crystallized intelligence.’ And there are adaptive reasoning and problem-solving skills that are quite flexible, called ‘fluid intelligence,'” he said.

    Crystallized intelligence involves robust connections, the result of months or years of neural traffic on well-worn pathways. Fluid intelligence involves weaker, more transient pathways and connections that are formed when the brain tackles unique or unusual problems.

    “Rather than forming permanent connections, we are constantly updating our prior knowledge, and this involves forming new connections,” Barbey said. The more readily the brain forms and reforms its connectivity in response to changing needs, the better it works, he said.

    Although researchers have known that flexibility is an important characteristic of human brain function, only recently has the idea emerged that flexibility provides the basis for human intelligence, he said.

    “General intelligence requires both the ability to flexibly reach nearby, easy-to-access states — to support crystallized intelligence — but also the ability to adapt and reach difficult-to-access states — to support fluid intelligence,” Barbey said. “What my colleagues and I have come to realize is that general intelligence does not originate from a single brain region or network. Emerging neuroscience evidence instead suggests that intelligence reflects the ability to flexibly transition between network states.”


  6. Videogame study suggests link between intelligence and skill at game

    November 27, 2017 by Ashley

    From the University of York press release:

    Researchers at the University of York have discovered a link between young people’s ability to perform well at two popular video games and high levels of intelligence.

    Studies carried out at the Digital Creativity Labs (DC Labs) at York found that some action strategy video games can act like IQ tests. The researchers’ findings are published today in the journal PLOS ONE.

    The York researchers stress the studies have no bearing on questions such as whether playing computer games makes young people smarter or otherwise. They simply establish a correlation between skill at certain online games of strategy and intelligence.

    The researchers focused on ‘Multiplayer Online Battle Arenas’ (MOBAs) — action strategy games that typically involve two opposing teams of five individuals — as well as multiplayer ‘First Person Shooter’ games. These types of games are hugely popular with hundreds of millions of players worldwide.

    The team from York’s Departments of Psychology and Computer Science carried out two studies. The first examined a group of subjects who were highly experienced in the MOBA League of Legends — one of the most popular strategic video games in the world with millions of players each day.

    In this study, the researchers observed a correlation between performance in the strategic game League of Legends and performance in standard paper-and-pencil intelligence tests.

    The second study analysed big datasets from four games: Two MOBAs (League of Legends and Defence of the Ancients 2 (DOTA 2)) and two ‘First Person Shooters’ (Destiny and Battlefield 3). First Person Shooters (FPSs) are games involving shooting enemies and other targets, with the player viewing the action as though through the eyes of the character they are controlling.

    In this second study, they found that for large groups consisting of thousands of players, performance in MOBAs and IQ behave in similar ways as players get older. But this effect was not found for First Person Shooters, where performance declined after the teens.

    The researchers say the correlation between ability at action strategy video games such as League of Legends and Defence of the Ancients 2 (DOTA 2) and a high IQ is similar to the correlation seen in other more traditional strategy games such as chess.

    Corresponding author Professor Alex Wade of the University of York’s Department of Psychology and Digital Creativity Labs said: “Games such as League of Legends and DOTA 2 are complex, socially-interactive and intellectually demanding. Our research would suggest that your performance in these games can be a measure of intelligence.

    “Research in the past has pointed to the fact that people who are good at strategy games such as chess tend to score highly at IQ tests. Our research has extended this to games that millions of people across the planet play every day.”

    The discovery of this correlation between skill and intelligence opens up a huge new data source. For example, as ‘proxy’ tests of IQ, games could be useful at a global population level in fields such as ‘cognitive epidemiology’ — research that examines the associations between intelligence and health across time — and as a way of monitoring cognitive health across populations.

    Athanasios Kokkinakis, a PhD student with the EPSRC Centre for Intelligent Games and Game Intelligence (IGGI) research programme at York, is the lead author on the study.

    He said: “Unlike First Person Shooter (FPS) games where speed and target accuracy are a priority, Multiplayer Online Battle Arenas rely more on memory and the ability to make strategic decisions taking into account multiple factors.

    “It is perhaps for these reasons that we found a strong correlation between skill and intelligence in MOBAs.”

    Co-author Professor Peter Cowling, Director of DC Labs and the IGGI programme at York, said: “This cutting-edge research has the potential for substantial impact on the future of the games and creative industries — and on games as a tool for research in health and psychology.

    “The IGGI programme has 48 excellent PhD students working with industry and across disciplines — there is plenty more to come!”


  7. Study suggests visual intelligence is not the same as IQ

    November 17, 2017 by Ashley

    From the Vanderbilt University press release:

    Just because someone is smart and well-motivated doesn’t mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

    That is the implication of a new study which shows for the first time that there is a broad range of differences in people’s visual ability and that these variations are not associated with individuals’ general intelligence, or IQ. The research is reported in a paper titled “Domain-specific and domain-general individual differences in visual object recognition” published in the September issue of the journal Cognition and the implications are discussed in a review article in press at Current Directions in Psychological Science.

    “People may think they can tell how good they are at identifying objects visually,” said Isabel Gauthier, David K. Wilson Professor of Psychology at Vanderbilt University, who headed the study. “But it turns out that they are not very good at evaluating their own skills relative to others.”

    In the past, research in visual object recognition has focused largely on what people have in common, but Gauthier became interested in the question of how much visual ability varies among individuals. To answer this question, she and her colleagues had to develop a new test, which they call the Novel Object Memory Test (NOMT), to measure people’s ability to identify unfamiliar objects.

    Gauthier first wanted to gauge public opinions about visual skills. She did so by surveying 100 laypeople using the Amazon Mechanical Turk crowdsourcing service. She found that respondents generally consider visual tasks as fairly different from other tasks related to general intelligence. She also discovered that they feel there is less variation in people’s visual skills than there is in non-visual skills such as verbal and math ability.

    The main problem that Gauthier and colleagues had to address in assessing individuals’ innate visual recognition ability was familiarity. The more time a person spends learning about specific types of objects, such as faces, cars or birds, the better they get at identifying them. As a result, performance on visual recognition tests that use images of common objects are a complex mixture of people’s visual ability and their experience with these objects. Importantly, they have proven to be a poor predictor of how well someone can learn to identify objects in a new domain.

    Gauthier addressed this problem by using novel computer-generated creatures called greebles, sheinbugs and ziggerins to study visual recognition. The basic test consists of studying six target creatures, followed by a number of test trials displaying creatures in sets of three. Each set contains a creature from the target group along with two unfamiliar creatures, and the participant is asked to pick out the creature that is familiar.

    Analyzing the results from more than 2000 subjects, Gauthier and colleagues discovered that the ability to recognize one kind of creature was well predicted by how well subjects could recognize the other kind, although these objects were visually quite different. This confirmed the new test can predict the ability to learn new categories.

    The psychologists also used performance on several IQ-related tests and determined that the visual ability measured on the NOMT is distinct from and independent of general intelligence.

    “This is quite exciting because performance on cognitive skills is almost always associated with general intelligence,” Gauthier said. “It suggests that we really can learn something new about people using these tests, over and beyond all the abilities we already know how to measure.” Although the study confirms the popular intuition that visual skill is different from general intelligence, it found that individual variations in visual ability are much larger than most people think. For instance, on one metric, called the coefficient of variation, the spread of people was wider on the NOMT than on a nonverbal IQ test.

    “A lot of jobs and hobbies depend on visual skills,” Gauthier said. “Because they are independent of general intelligence, the next step is to explore how we can use these tests in real-world applications where performance could not be well predicted before.”


  8. So-called ‘bright girl effect’ does not last into adulthood, study finds

    September 7, 2017 by Ashley

    From the Case Western Reserve University press release:

    The notion that young females limit their own progress based on what they believe about their intelligence — called the “bright girl effect” — does not persist into adulthood, according to new research from Case Western Reserve University.

    The study also found almost no relationship between gender and intelligence “mindset,” which refers to a person’s beliefs about his or her own intellectual potential.

    According to mindset theory — developed by Carol Dweck, a psychology professor at Stanford University — some people have “growth” mindsets while others have “fixed” mindsets.

    A growth mindset, considered a positive trait, is more likely to lead a person to try to overcome challenges, believing intelligence can improve with effort.

    Fixed mindsets, often seen as a negative, are more likely to lead people to avoid difficult tasks and assume failure is due to intelligence levels that cannot be changed.

    Because girls are thought to mature earlier than boys, according to mindset theory, they are often praised for their attributes — how they “are.” More of this type of praise is given to “bright” girls, which leads them to believe their cognitive abilities are more or less set in stone.

    Published in the journal Intelligence, the new research found little indication such a phenomenon exists in adult women.

    “Overall, we saw no reliable evidence for a relationship between women’s intelligence and their mindsets,” said Brooke Macnamara, an assistant professor of psychological sciences at Case Western Reserve and co-author of the study. “Our results do not support the idea that men and women differ in their beliefs about intelligence.”

    The findings run contrary to some cornerstones of the mindset field: that females, especially smarter females, tend to believe their intelligence levels are static, and that differences in childhood praise given to boys and girls can heavily influence a person’s later beliefs about their own intelligence.

    The study

    In three studies, nearly 400 total participants were given an intelligence test and a measure developed by Dweck that discerns a person’s attitudes toward the plasticity of their own intelligence and talent.

    They were asked, for example, how much they agreed with such statements as, You can always substantially change how intelligent you are, and No matter who you are, you can significantly change your level of intelligence.

    The studies are among the first to investigate three factors among adults: measured intelligence, intelligence mindset, and gender.

    Evidence for the bright girl effect is mostly based on three academic studies conducted with children and adolescents from the 1980’s.

    “These studies help fill in gaps in the mindset research,” said Macnamara. “Some past research has suggested a ‘bright girl effect’ — gender differences among children. However, a ‘bright woman effect’ — gender differences among adults — seemed to be an untested assumption. Across our studies, there were no consistent relationships among intelligence, mindset and gender. Our research did not support the idea of a ‘bright woman effect.'”


  9. Higher IQ in childhood is linked to a longer life

    July 20, 2017 by Ashley

    From the BMJ press release:

    Higher intelligence (IQ) in childhood is associated with a lower lifetime risk of major causes of death, including heart disease, stroke, smoking related cancers, respiratory disease and dementia, finds a study published by The BMJ today.

    It is the largest study to date reporting causes of death in men and women across the life course, and the findings suggest that lifestyle, especially tobacco smoking, is an important component in the effect of intelligence on differences in mortality.

    Previous studies have shown that, on average, individuals with higher IQs tend to live a little longer than those with lower IQs, but these are largely based on data from male conscripts followed up only to middle adulthood.

    So a team of researchers from the University of Edinburgh set out to examine the association between intelligence test scores measured at age 11 and leading causes of death in men and women up to age 79.

    Their findings are based on data from 33,536 men and 32,229 women born in Scotland in 1936, who took a validated childhood intelligence test at age 11, and who could be linked to cause of death data up to December 2015.

    Cause of death included coronary heart disease, stroke, specific cancers, respiratory disease, digestive disease, external causes (including suicide and death from injury), and dementia.

    After taking account of several factors (confounders) that could have influenced the results, such as age, sex and socioeconomic status, the researchers found that higher childhood intelligence was associated with a lower risk of death until age 79.

    For example, a higher test score was associated with a 28% reduced risk of death from respiratory disease, a 25% reduced risk of death from coronary heart disease, and a 24% reduced risk of death from stroke.

    Other notable associations were seen for deaths from injury, smoking related cancers (particularly lung and stomach), digestive disease, and dementia. There was no evident association between childhood intelligence and death from cancers not related to smoking.

    The authors outline some study limitations which could have introduced bias. However, key strengths include the whole population sample, 68-year follow up, and ability to adjust for important confounders.

    They also point out that significant associations remained after further adjustment for smoking and socioeconomic status, suggesting that these factors did not fully account for mortality differences. And they say future studies “would benefit from measures of the cumulative load of such risk factors over the life course.”

    This study is the largest to date reporting causes of death across the life course, and it provides us with interesting results, say researchers based in Sweden, in a linked editorial.

    “Importantly, it shows that childhood IQ is strongly associated with causes of death that are, to a great extent, dependent on already known risk factors,” they write. And they suggest that “tobacco smoking and its distribution along the socioeconomic spectrum could be of particular importance here.”

    In conclusion, they say: “It remains to be seen if this is the full story or if IQ signals something deeper, and possibly genetic, in its relation to longevity.”


  10. Consequences of lead exposure in childhood

    April 4, 2017 by Sue

    From the Duke University press release:

    A long-term study of more than 500 children who grew up in the era of leaded gasoline has shown that their exposure to the powerful neurotoxin may have led to a loss of intelligence and occupational standing by the time they reached age 38.

    The effects are slight, but significant, showing that the higher the blood lead level in childhood, the greater the loss of IQ points and occupational status in adulthood. The study appears Wednesday in the Journal of the American Medical Association.

    Study participants are part of a life-long examination of more than 1,000 people born in Dunedin, New Zealand in 1972 and 1973. During their childhood, New Zealand had some of the highest gasoline lead levels in the world.

    From birth to adulthood, these people have regularly been assessed for cognitive skills such as perceptual reasoning and working memory. At age 11, blood samples were collected from 565 of them which were then tested for lead.

    Participants who were found to carry more than 10 micrograms of lead per deciliter of blood at age 11 had IQs at age 38 that were, on average, 4.25 points lower than their less lead-exposed peers. They were also found to have lost IQ points relative to their own childhood scores.

    The study found that for each 5-microgram increase in blood lead, a person lost about 1.5 IQ points.

    The mean blood lead level of the children at age 11 was 10.99 micrograms per deciliter of blood, slightly higher than the historical “level of concern” for lead exposure. Today’s reference value at which the CDC recommends public health intervention is half that, 5 micrograms per deciliter, a level which 94 percent of children in the study exceeded. No safe blood lead level in children has been identified.

    “This is historical data from an era when lead levels like these were viewed as normal in children and not dangerous, so most of our study participants were never given any special treatment,” said Terrie Moffitt, the senior author of the study and Duke’s Nannerl O. Keohane University Professor of psychology & neuroscience and psychiatry & behavioral sciences.

    “This case is different from the one in Flint, Michigan and other cities where lead in the drinking water has led public health officials to begin special interventions for those children,” Moffitt said. Flint’s children are receiving regular blood monitoring and expanded early childhood education, behavioral health services and special nutrition with the federal government’s support. “Interventions of this sort are intended to forestall the sorts of effects we’ve measured in this study,” she said.

    What makes the New Zealand case an important natural experiment is that automobile traffic goes through all neighborhoods. Unlike exposures to leaded paint or lead pipes in older structures, which pose more of a threat to poorer families, the exposure to leaded gasoline fumes was distributed relatively evenly across all social strata.

    Beginning in the 1920s, a compound called tetra-ethyl-lead was added to gasoline for its ability to boost octane ratings and raise engine power. The lead itself didn’t burn however, and emerged from tailpipes as elemental lead and lead oxides which settled as a particulate in soils around areas where cars were common.

    Soil hangs on tightly to lead particles and soils next to busy roads have been found to have the highest lead concentrations from the leaded gasoline era. Children playing outside were prone to either breathe in lead-laden dust, or swallow small amounts of leaded soil.

    In either case, lead can accumulate in the child’s bloodstream. It then settles into the bones, teeth and soft tissues and accumulates in the body over time.

    Leaded gasoline was phased out in the U.S. and New Zealand between the mid-1970s and the mid-1990s, but is still used in some Asian and middle eastern countries.

    “Regardless of where you start in life, lead is going to exert a downward pull,” said Avshalom Caspi, Edward M. Arnett Professor of psychology & neuroscience and psychiatry & behavioral sciences at Duke, who is a co-author on the paper. A neurotoxin exposure that affects all parts of society relatively equally would move the entire curve of IQ and social status downward. “If everyone takes a hit from environmental pollutants, society as a whole suffers.”

    The study also compared changes in social standing using a measure from the New Zealand government that plots families on a 6-point scale. The childhood social status of each child’s family was compared to their adult standing at age 38. Children who were over 10 micrograms of lead attained occupations with socioeconomic status levels four-tenths lower than their less-exposed peers.

    “The downward social mobility we see mirrors the trend in IQ,” said Aaron Reuben, a Duke psychology graduate student who is first author on the study. After various statistical controls were applied to the data, “the decline in occupational status is partially but significantly explained by the loss of IQ,” he said. “If you’re above the historic level of concern (for lead exposure), you’re doing worse on both.”

    The effects of lead exposure are probably long-lasting as well, Reuben added. “The cognitive deficits associated with lead persisted for decades, and showed in the kinds of occupations people got.”