A review of brain imaging and occupation data from 588 patients diagnosed with frontotemporal dementia has found that among the dementias affecting those 65 years and younger, FTD is as common as Alzheimer's disease. The study also found that the side of the brain first attacked (unlike Alzheimer’s, FTD typically begins with tissue loss in one hemisphere) is influenced by the person’s occupation.
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Analysis of DNA and lifestyle data from a representative group of 2,500 U.S. middle- and high-school students tracked from 1994 to 2008 in the National Longitudinal Study of Adolescent Health has revealed that lower academic performance was associated with three dopamine gene variants. Having more of the dopamine gene variants (three rather than one, say) was associated with a significantly lower GPA.
Following a monkey study that found training in spatial memory could raise females to the level of males, and human studies suggesting the video games might help reduce gender differences in spatial processing (see below for these), a new study shows that training in spatial skills can eliminate the gender difference in young children. Spatial ability, along with verbal skills, is one of the two most-cited cognitive differences between the sexes, for the reason that these two appear to be the most robust.
Type 2 diabetes is known to increase the risk of cognitive impairment in old age. Now analysis of data from 41 older diabetics (aged 55-81) and 458 matched controls in the Victoria Longitudinal Study has revealed that several other factors make it more likely that an older diabetic will develop cognitive impairment. These factors are: having higher (though still normal) blood pressure, having gait and balance problems, and/or reporting yourself to be in bad health regardless of actual problems.
Low levels of DHA, an omega-3 fatty acid, have been found in the brains of those with Alzheimer's disease, but the reason has not been known. A new study has found that lower levels of DHA in the liver (where most brain DHA is manufactured) were correlated with greater cognitive problems in the Alzheimer’s patients. Moreover, comparison of postmortem livers from Alzheimer’s patients and controls found reduced expression of a protein that converts a precursor acid into DHA, meaning the liver was less able to make DHA from food.
Reports on cognitive decline with age have, over the years, come out with two general findings: older adults do significantly worse than younger adults; older adults are just as good as younger adults. Part of the problem is that there are two different approaches to studying this, each with their own specific bias. You can keep testing the same group of people as they get older — the problem with this is that they get more and more practiced, which mitigates the effects of age.
A number of studies have found that source memory (knowing where you heard/read/experienced something) is a particular problem for older adults. Destination memory (knowing who you’ve told) is an area that has been much less studied. Last year I reported on why destination memory is difficult for all of us (my report is repeated below). A follow-up study has found not only that destination memory is a particular problem for older adults, but that it is in fact a worse problem than source memory.
A study following over 300 Mexican-American children living in an agricultural community has found that their prenatal exposure to organophosphate pesticides (measured by metabolites in the mother’s urine during pregnancy) was significantly associated with attention problems at age 5. This association was stronger among boys, and stronger with age (at 3 ½ the association, although present, did not reach statistical significance — perhaps because attention disorders are much harder to recognize in toddlers).
Neurofibromatosis type 1 (NF1) is the most common cause of learning disabilities, caused by a mutation in a gene that makes a protein called neurofibromin. Mouse research has now revealed that these mutations are associated with higher levels of the inhibitory neurotransmitter GABA in the medial prefrontal cortex. Brain imaging in humans with NF1 similarly showed reduced activity in the prefrontal cortex when performing a working memory task, with the levels of activity correlating with task performance.
Two independent studies have found that students whose birthdays fell just before their school's age enrollment cutoff date—making them among the youngest in their class—had a substantially higher rate of ADHD diagnoses than students who were born later. One study, using data from the Early Childhood Longitudinal Study-Kindergarten cohort, found that ADHD diagnoses among children born just prior to their state’s kindergarten eligibility cutoff date are more than 60% more prevalent than among those born just afterward (who therefore waited an extra year to begin school).