amyloid beta

More evidence that stress increases risk of Alzheimer's

  • A stress hormone has been found to be associated with more amyloid-beta protein, in mice and human neurons.
  • The finding helps explain why stress is a risk factor for Alzheimer's.
  • A previous 38-year study supports this with the finding that women who scored highly in "neuroticism" in middle age, had a greater chance of later developing Alzheimer's.
  • This link was largely accounted for by chronic stress experienced by these women over the four decades.

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.

It appears that CRF causes the enzyme gamma secretase to increase its activity. This produces more amyloid-beta.

The finding supports the idea that reducing stress is one part of reducing your risk of developing Alzheimer's.

A neurotic personality increases the risk of Alzheimer's disease

An interesting study last year supports this.

The study, involving 800 women who were followed up some 40 years after taking a personality test, found that women who scored highly in "neuroticism" in middle age, have a greater chance of later developing Alzheimer's. People who have a tendency to neuroticism are more readily worried, distressed, and experience mood swings. They often have difficulty in managing stress.

The women, aged 38 to 54, were first tested in 1968, with subsequent examinations in 1974, 1980, 1992, 2000, and 2005. Neuroticism and extraversion were assessed in 1968 using the Eysenck Personality Inventory. The women were asked whether they had experienced long periods of high stress at each follow-up.

Over the 38 years, 153 developed dementia (19%), of whom 104 were diagnosed with Alzheimer's (13% of total; 68% of those with dementia).

A greater degree of neuroticism in midlife was associated with a higher risk of Alzheimer's and long-standing stress. This distress accounted for a lot of the link between neuroticism and Alzheimer's.

Extraversion, while associated with less chronic stress, didn't affect Alzheimer's risk. However, high neuroticism/low extraversion (shy women who are easily worried) was associated with the highest risk of Alzheimer's.

The finding supports the idea that long periods of stress increase the risk of Alzheimer's, and points to people with neurotic tendencies, who are more sensitive to stress, as being particularly vulnerable.

http://www.eurekalert.org/pub_releases/2015-09/uof-uhr091615.php

http://www.eurekalert.org/pub_releases/2014-10/uog-anp101414.php

Reference: 

Topics: 

tags problems: 

tags development: 

tags memworks: 

Diabetes and tau tangles linked independently of Alzheimer's

  • Type 2 diabetes is known to increase the risk of Alzheimer's disease.
  • In a reasonably large study, diabetes was found to be linked with higher levels of tau protein, regardless of the presence of dementia.
  • Diabetes was also linked with greater brain shrinkage.
  • The finding adds to evidence that diabetes increases the risk of cognitive impairment in old age.

A study involving older adults has found that diabetes was associated with higher levels of tau protein and greater brain atrophy.

The study involved 816 older adults (average age 74), of whom 397 had mild cognitive impairment, 191 had Alzheimer's disease, and 228 people had no cognitive problems. Fifteen percent (124) had diabetes.

Those with diabetes had greater levels of tau protein in the spinal and brain fluid regardless of cognitive status. Tau tangles are characteristic of Alzheimer's.

Those with diabetes also had cortical tissue that was an average of 0.03 millimeter less than those who didn't have diabetes, regardless of their cognitive status. This greater brain atrophy in the frontal and parietal cortices may be partly related to the increase in tau protein.

There was no link between diabetes and amyloid-beta, the other main pathological characteristic of Alzheimer's.

Previous research has indicated that people with type 2 diabetes have double the risk of developing dementia. Previous research has also found that those who had been diabetic for longer had a greater degree of brain atrophy

The findings support the idea that type 2 diabetes may have a negative effect on cognition independent of dementia, and that this effect may be driven by an increase in tau phosphorylation.

http://www.eurekalert.org/pub_releases/2015-09/aaon-dab082715.php

Reference: 

tags lifestyle: 

Topics: 

tags problems: 

Alzheimer's amyloid clumps found in young adult brains

An examination of the brains of three groups of deceased individuals (13 cognitively normal, aged 20-66; 16 non-demented older adults, aged 70-99; 21 individuals with Alzheimer's, aged 60-95) has found that amyloid starts to accumulate and clump inside basal forebrain cholinergic neurons in young adulthood. Other neurons didn't show the same extent of amyloid accumulation. Basal forebrain cholinergic neurons are the first to be affected, and to die, in aging and Alzheimer's.

http://www.eurekalert.org/pub_releases/2015-03/nu-aac022515.php

Reference: 

Source: 

tags development: 

Topics: 

tags problems: 

Site of plaque buildup matters

Analysis of brain scans and cognitive scores of 64 older adults from the NIA's Baltimore Longitudinal Study of Aging (average age 76) has found that, between the most cognitively stable and the most declining (over a 12-year period), there was no significant difference in the total amount of amyloid in the brain, but there was a significant difference in the location of amyloid accumulation.

Mynd: 

tags problems: 

tags development: 

New biomarkers for early Alzheimer's diagnosis

Analysis of 40 spinal marrow samples, 20 of which belonged to Alzheimer’s patients, has identified six proteins in spinal fluid that can be used as markers for Alzheimer's. The analysis focused on 35 proteins that are associated with the lysosomal network — involved in cleaning and recycling beta amyloid.

Mynd: 

tags problems: 

tags development: 

Tracking preclinical Alzheimer's progression

New research supports the classification system for preclinical Alzheimer’s proposed two years ago. The classification system divides preclinical Alzheimer's into three stages:

Stage 1: Levels of amyloid beta begin to decrease in the spinal fluid. This indicates that the substance is beginning to form plaques in the brain.

Stage 2: Levels of tau protein start to increase in the spinal fluid, indicating that brain cells are beginning to die. Amyloid beta levels are still abnormal and may continue to fall.

Mynd: 

tags problems: 

tags development: 

Tau-amyloid ratio predicts MCI

Initial findings from an analysis of cerebrospinal fluid taken between 1995 and 2005 from 265 middle-aged healthy volunteers, of whom 75% had a close family member with Alzheimer’s disease, has found that the ratios of phosphorylated tau and amyloid-beta could predict mild cognitive impairment more than five years before symptom onset — the more tau and less amyloid-beta, the more likely

Mynd: 

tags problems: 

tags development: 

Plaques tell which MCI patients will progress to Alzheimer’s

A three-year study involving 152 adults aged 50 and older, of whom 52 had been recently diagnosed with mild cognitive impairment and 31 were diagnosed with Alzheimer's disease, has found that those with mild or no cognitive impairment who initially had amyloid-beta plaques showed greater cognitive decline than those whose brain scans were negative for plaques.

Mynd: 

tags problems: 

tags development: 

Pages

Subscribe to RSS - amyloid beta