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.
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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.
Because male superiority in mental rotation appears to be evident at a very young age, it has been suggested that testosterone may be a factor. To assess whether females exposed to higher levels of prenatal testosterone perform better on mental rotation tasks than females with lower levels of testosterone, researchers compared mental rotation task scores between twins from same-sex and opposite-sex pairs.
Manganese exposure in the workplace is known to have neurotoxic effects, but manganese occurs naturally in soil and sometimes in groundwater. One region where the groundwater contains naturally high levels of manganese is Quebec. A study involving 362 Quebec children, aged 6-13, has measured both the concentrations of metals (manganese, iron, copper, lead, zinc, arsenic, magnesium and calcium) in their tap water, and their cognitive abilities.
When children learn to count, they do so by rote. Understanding what the numbers really mean comes later. This is reflected in the way children draw a number line. In the beginning, they typically put more space between the smaller numbers, with the larger numbers all scrunched up at the end (a logarithmic number line). Eventually they progress to a number line where the numbers are evenly spaced (linear number line).
I’m not at all sure why the researcher says they were “stunned” by these findings, since it doesn’t surprise me in the least, but a series of experiments into the role of imagination in creating false memories has revealed that people who had watched a video of someone else doing a simple action often remembered doing the action themselves two weeks later.
Over the years I’ve reported on a number of studies investigating the effect of chemotherapy on the brain. A new study uses brain imaging, before and after treatment for breast cancer, to show that there is an anatomic basis for “chemobrain” complaints.
Brain imaging of 49 children aged 9-10 has found that those who were physically fit had a hippocampus significantly bigger (around 12%) than those who were not fit. Animal studies and those with older adults have shown that aerobic exercise increases the growth of new brain cells in the hippocampus. Physical fitness was measured by how efficiently the children used oxygen while running on a treadmill. Fitter children also did better on tests of relational (but not item) memory, and this association was directly mediated by hippocampal volume.
Children with autism often focus intently on a single activity or feature of their environment. A study involving 17 autistic children (6-16 years) and 17 controls has compared brain activity as they watched a silent video of their choice while tones and vibrations were presented, separately and simultaneously.
Many survivors of childhood cancer experience cognitive problems as a result of their treatment. The drug methylphenidate (marketed under several names, the best known of which is Ritalin) has previously been shown to help attention problems in such survivors in the short term. Now a new study demonstrates that it can also be of benefit in the long term.