Alzheimers

Providing some support for the finding I recently reported — that problems with semantic knowledge in those with mild cognitive impairment (MCI) and Alzheimer’s might be rooted in an inability to inhibit immediate perceptual information in favor of conceptual information — a small study has found that executive function (and inhibitory control in particular) is impaired in far more of those with MCI than was previously thought.

Previous research has pointed to an association between not having teeth and a higher risk of cognitive decline and dementia. One reason might have to do with inflammation — inflammation is a well-established risk factor, and at least one study has linked gum disease to a higher dementia risk. Or it might have to do with the simple mechanical act of chewing, reducing blood flow to the brain. A new study has directly investigated chewing ability in older adults.

Sad to say, another large study has given the thumbs down to ginkgo biloba preventing Alzheimer’s disease.

The randomized, double-blind trial took place over five years, involving 2854 older adults (70+) who had presented to their primary care physician with memory complaints. Half were given a twice-daily dose of 120 mg standardised ginkgo biloba extract and half a placebo.

New research suggests that reliance on the standard test Alzheimer's Disease Assessment Scale—Cognitive Behavior Section (ADAS-Cog) to measure cognitive changes in Alzheimer’s patients is a bad idea. The test is the most widely used measure of cognitive performance in clinical trials.

A small study shows how those on the road to Alzheimer’s show early semantic problems long before memory problems arise, and that such problems can affect daily life.

There's quite a bit of evidence now that socializing — having frequent contact with others — helps protect against cognitive impairment in old age. We also know that depression is a risk factor for cognitive impairment and dementia. There have been hints that loneliness might also be a risk factor. But here’s the question: is it being alone, or feeling lonely, that is the danger?

A large Dutch study, following 2173 older adults for three years, suggests that it is the feeling of loneliness that is the main problem.

It’s been unclear whether hormone therapy helps older women reduce their risk of Alzheimer’s or in fact increases the risk. To date, the research has been inconsistent, with observational studies showing a reduced risk, and a large randomized controlled trial showed an increased risk. As mentioned before, the answer to the inconsistency may lie in the timing of the therapy. A new study supports this view.

I reported a few months ago on some evidence of a link between disturbed sleep and the development of Alzheimer’s. Now a mouse study adds to this evidence.

The mouse study follows on from an earlier study showing that brain levels of amyloid beta naturally rise when healthy young mice are awake and drop after they go to sleep, and that sleep deprivation disrupted this cycle and accelerated the development of amyloid plaques. This natural rhythm was confirmed in humans.

Memory problems in those with mild cognitive impairment may begin with problems in visual discrimination and vulnerability to interference — a hopeful discovery in that interventions to improve discriminability and reduce interference may have a flow-on effect to cognition.

HIV-associated dementia occurs in around 30% of untreated HIV-positive patients. Surprisingly, it also is occasionally found in some patients (2-3%) who are being successfully treated for HIV (and show no signs of AIDS).

A new study may have the answer for this mystery, and suggest a solution. Moreover, the answer may have general implications for those experiencing cognitive decline in old age.