amyloid beta

Lowering blood pressure prevents worsening brain damage in elderly

A clinical trial involving 199 hypertensive older adults (average age 81) found that those who took medicine to keep their 24-hour systolic blood pressure around 130 mm Hg for three years showed 40% less accumulation of white matter lesions compared with those taking medicine to maintain a systolic blood pressure around 145 mm Hg.

Although first reported in 1816, the fact that the brain is surrounded by lymphatic vessels, which connect the brain and the immune system, was only rediscovered in 2015.

A diet containing compounds found in green tea and carrots reversed Alzheimer's-like symptoms in mice genetically programmed to develop the disease. The two compounds were EGCG (epigallocatechin-3-gallate), a key ingredient in green tea, and FA (ferulic acid), which is found in carrots, tomatoes, rice, wheat and oats.

A mouse study has found that canola oil in the diet was associated with worsened memory, worsened learning ability, and weight gain in Alzheimer's mice.

Canola oil-treated animals also had greatly reduced levels of amyloid beta 1-40 (the “good” version), leading to more amyloid-beta plaques (made from amyloid beta 1-42), and a significant decrease in synapses.

The mice were given the equivalent of about two tablespoons of canola oil daily. The mice began their enriched diet at 6 months of age, before they developed any signs of Alzheimer's.

Periodontitis raises dementia risk

A 10-year South Korean study using data from 262,349 older adults (50+) has found that those with chronic periodontitis had a 6% higher risk for dementia than did people without periodontitis. This connection was true despite behaviors such as smoking, consuming alcohol, and remaining physically active.

https://www.eurekalert.org/pub_releases/2019-03/ags-pmr031519.php

Data from the Harvard Aging Brain Study found that higher amyloid beta levels were associated with increasing anxiety symptoms in cognitively normal older adults. The results suggest that worsening anxious-depressive symptoms may be an early predictor of elevated amyloid beta levels.

The study involved 270 cognitively healthy older adults (62-90). For five years, participants were annually assessed for depression, apathy-anhedonia, dysphoria, and anxiety.

Aging linked to impaired garbage collection in the brain

A mouse study has shown that, as cells age, their ability to remove damaged proteins and structures declines.

The process of waste management, called autophagy, involves a component within the cell (an autophagosome) engulfing misfolded proteins or damaged structures (putting them in a garbage bag, essentially). The autophagosome then fuses with a second cellular structure, called a lysosome, that contains the enzymes needed to breakdown the garbage, allowing the components to be recycled and reused.

Data from 1,215 older adults, of whom 173 (14%) were African-American, has found that, although brain scans showed no significant differences between black and white participants, cerebrospinal fluid (CSF) showed significantly lower levels of the brain protein tau in African-Americans.

While both groups showed the same (expected) pattern of higher tau levels being associated with greater chance of cognitive impairment, the absolute amounts of tau protein were consistently lower in African-Americans.

A study involving both mice and human cells adds to evidence that stress is a risk factor for Alzheimer's.

The study found that mice who were subjected to acute stress had more amyloid-beta protein in their brains than a control group. Moreover, they had more of a specific form of the protein, one that has a particularly pernicious role in the development of Alzheimer's disease.

When human neurons were treated with the stress hormone corticotrophin releasing factor (CRF), there was also a significant increase in the amyloid proteins.