August 23, 2009 at 3:03 pm #32098
note: this is pretty interesting, and makes sense: decreased blood flow to brain (diverted to fat & inefficient organs) causes brain to feel starved and begin dying off. Exercise (= qigong) is the best solution to keeping the circulation up and fighting off dementia and Alzheimers. Or become a breatharian. – Michael
EXPANDING WAISTLINES MAY CAUSE SHRINKING BRAINS
By Nora Schultz
August 23, 2009
Brain regions key to cognition are smaller in older people who are obese
compared with their leaner peers, making their brains look up to 16 years
older than their true age. As brain shrinkage is linked to dementia, this
adds weight to the suspicion that piling on the pounds may up a person’s
risk of the brain condition.
Previous studies suggested that obesity in middle age increases the risk of
dementia decades later, which is accompanied by increased brain shrinkage
compared with leaner people. Now brain scans of older people have revealed
the areas that are hardest hit, as well as the full extent of brain size
differences between obese people and those of average weight.
From brain scans initially carried out for a different study, Paul Thompson
from the University of California in Los Angeles and colleagues selected 94
from people in their 70s who were still “cognitively normal” five years
after the scan. This was to exclude people with disorders that might have
confused the results. The researchers then transformed these scans into
detailed three-dimensional maps.
People with higher body mass indexes had smaller brains on average, with the
frontal and temporal lobes — important for planning and memory,
respectively — particularly affected. While no one knows whether these
people are more likely to develop dementia, a smaller brain is indicative of
destructive processes that can develop into dementia.
The team also found that the brains of the 51 overweight people were 6 per
cent smaller than those of their normal-weight counterparts, on average, and
those of the 14 obese people were 8 per cent smaller. “The brains of
overweight people looked eight years older than the brains of those who were
lean, and 16 years older in obese people,” says Thompson.
High insulin levels and type 2 diabetes tend to accompany being overweight
and are risk factors for brain tissue loss and dementia. However, the
relationship between brain size and body mass index still stood when the
researchers accounted for these conditions, indicating that body fat levels
may be linked directly to brain shrinkage. Thompson suggests that as
increased body fat ups the chances of having clogged arteries, which can
reduce blood and oxygen flow to brain cells, the resulting reduction in
metabolism could cause brain cell death and the shrinking seen.
In an as yet unpublished study, Thompson’s team has shown that exercise,
which improves cardiovascular health and blood flow, protects the very brain
regions that had shrunk in the current study. “The most strenuous kind of
exercise can save about the same amount of brain tissue that is lost in the
obese,” he says. This indicates that it is blood flow that drives brain
health, not the other way round. As these areas undergo the most remodelling
throughout adult life, they may be more sensitive to any changes in oxygen
supply and nutrients, Thompson suggests.
But Deborah Gustafson at the University of Gothenburg in Sweden, who
previously found that overweight women had less brain tissue than their
leaner counterparts, questions whether obesity is driving brain atrophy or
vice versa. She points out that brain atrophy in the frontal and temporal
lobes, which also control eating behaviour and metabolism, could cause
weight gain. “There are not enough longitudinal data available for us to
know which is the chicken and which is the egg.”
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