Because long-term cognitive decline can occur in some older adults after undergoing surgery, there has been some concern that exposure to anesthesia may be associated with increased dementia risk. It is therefore pleasing to report that data from the very large, long-running Mayo Clinic Study, the Rochester Epidemiology Project, has found that receiving general anesthesia for procedures after age 45 is not a risk factor for developing dementia.
Most of the (few) approved Alzheimer’s drugs are cholinesterase inhibitors — that is, they stop the breakdown of the neurotransmitter acetylcholine. A new study explains why they help. It appears they allow signals to enter the brain with more precision and less background noise.
We know that the E4 variant of the APOE gene greatly increases the risk of developing Alzheimer’s disease, but the reason is a little more mysterious. It has been thought that it makes it easier for amyloid plaques to form because it produces a protein that binds to amyloid beta. However, a new study shows that APOE and amyloid beta don’t bind together in cerebrospinal fluid and in fluids present outside cells grown in dishes, making it unlikely that they are binding together in the brain.
A study involving nearly 6,000 African American older adults has found those with a specific gene variant have almost double the risk of developing late-onset Alzheimer’s disease compared with African Americans who lack the variant. The size of the effect is comparable to that of the ‘Alzheimer’s gene’, APOE-e4.
The gene (ABCA7) is involved in the production of cholesterol and lipids. It also affects the transport of several important proteins, including amyloid precursor protein, which is involved in the production of amyloid-beta.
Analysis of data from 418 older adults (70+) has found that carriers of the ‘Alzheimer’s gene’, APOEe4, were 58% more likely to develop mild cognitive impairment compared to non-carriers. However, ε4 carriers with MCI developed Alzheimer’s at the same rate as non-carriers. The finding turns prevailing thinking on its head: rather than the gene increasing the risk of developing Alzheimer’s, it appears that it increases the risk of MCI — and people with MCI are the main source of new Alzheimer’s diagnoses.
New findings support a mathematical model predicting that the slow, steady firing of neurons in the dorsolateral prefrontal cortex that maintains visual representations in working memory relies on a class of NMDA receptors known as NR2B receptors. Blocking these receptors abolished persistent firing among pyramidal Delay cells.
In a large Mayo Clinic study, self-reported diet was found to be significantly associated with the risk of seniors developing mild cognitive impairment or dementia over a four-year period.
The olfactory bulb is in the oldest part of our brain. It connects directly to the amygdala (our ‘emotion center’) and our prefrontal cortex, giving smells a more direct pathway to memory than our other senses. But the olfactory bulb is only part of the system processing smells. It projects to several other regions, all of which are together called the primary olfactory cortex, and of which the most prominent member is the piriform cortex.
In a study involving 20 healthy older adults (mean age 69.3) and 29 older adults who had amnestic mild cognitive impairment (mean age 67.6), half the participants were randomly assigned to a high–saturated fat/high–simple carbohydrate diet (HIGH) and half to a low–saturated fat/low–simple carbohydrate diet (LOW) for four weeks, in order to investigate the effects on biomarkers associated with Alzheimer’s.
In a study in which 78 healthy elders were given 5 different tests and then tested for cognitive performance 18 months later, two tests combined to correctly predict nearly 80% of those who developed significant cognitive decline. These tests were a blood test to identify presence of the ‘Alzheimer’s gene’ (APOE4), and a 5-minute fMRI imaging scan showing brain activity during mental tasks.