Alzheimer’s Disease is only one cause of dementia. Until recently the diagnosis was based on the clinical symptoms along brain images the brain showing atrophy. The diagnosis was confirmed with a brain biopsy. Now there is an assay of proteins in the cerebrospinal fluid (CSF) can help specify the diagnosis.

Despite more than 5 million Americans with Alzheimer's disease, and millions more at risk, these CSF tests have yet to be widely adopted by neurologists. In part because the ability to make an improved early diagnosis raised the question: does this matter? The argument in favor of earlier diagnosis is being able to treat the disease and thus slow the progression. However, not only is there no "magic bullet" for the prevention of Alzheimer's disease, there is no bullet at all. The current treatments offer modest, temporary, and symptomatic improvement at best.
A more persuasive argument in support of the CSF test is this provides more accurate diagnosis when testing new, possibly effective, treatments. The success of clinical trials requires not only that the treatment be effective, but that all subjects be correctly diagnosed. Subjects who have other diseases contaminate the sample and confound results.

At present, CSF and other biomarker Alzheimer's testing should be reserved for patients who present a diagnostic dilemma and patients entering clinical trials.

Walking at least 6 miles per week appears to maintain brain volume and preserve memory in old age, according to new research. Kirk I. Erickson, PhD, with the University of Pittsburgh, Pennsylvania, and colleagues reported the findings in the October 13 online issue of Neurology.
"These findings are really quite astonishing," Dr. Erickson said. "Other studies have previously shown that exercise is related to brain function, but the fact that we found that walking as little as 1 mile a day is related to brain volume 9 years later, and dementia 13 years later, is truly novel and really quite impressive," he said.

According to the researchers, the volume of gray matter shrinks in late adulthood and often precedes cognitive impairment. Participation in physical activity and exercise has been "hypothesized to protect against the deterioration of brain tissue, but this hypothesis has not been tested in longitudinal studies."

In the current study, 299 dementia-free people from the Cardiovascular Health Cognition Study were assessed for physical activity, as measured by the number of blocks they walked in 1 week. Nine years after the physical activity assessment, magnetic resonance imaging (MRI) scans were used to measure brain size. Four years later, the participants were tested for cognitive impairment and dementia.

Participants who walked at least 72 blocks — approximately 6 to 9 miles — per week had more gray matter than people who walked less; however, walking more than 72 blocks did not appear to increase gray matter volume any further.

In the 4-year follow-up, 116 of the participants, or 40%, had developed cognitive impairment or dementia. Greater gray matter volume with physical activity was associated with a 2-fold reduced risk for cognitive impairment.
"Based on our results, we can conclude that there is a relation between the amount of walking earlier in life and brain volume in later adulthood and that greater volume of tissue related to walking is associated with a reduced risk of cognitive impairment," the study authors suggest.
Dr. Erickson added that much more work is needed from randomized trials that assign people to an exercise treatment for long periods. "Only under these conditions will we be able to determine the extent to which exercise augments brain function in late life," he said.

Here’s an interesting finding: the relation between the ability to lose weight and lack of sleep. According to the October 5 issue of the Annals of Internal Medicine, lack of sleep appears to compromise the efficacy of dieting to lose weight.

The study of 10 people conducted in a sleep laboratory showed that there are multiple hormonal changes associated with sleep and these may affect the ability of dieters to lose weight. Not getting enough sleep increased the subjects’ hunger, and affected their leptin and ghrelin serum concentrations (ghrelin is a hormone that reduces metabolism and promotes retention of fat). The study found that the reduced sleep decreased the proportion of weight lost as fat by 55%. Subjects who slept 8.5 hours per night lost a mean of 1.4 kg, and those who slept 5.5 hours per night lost a mean of 0.6 kg.

The major limitation to the study is that the number of subjects was quite small, so the results may not be generalized to the majority of dieters. However, I use any excuse I can to get my 8 hours of sleep.