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.
 The stress response neuropeptide CRF increases amyloid-β production by regulating γ-secretase activity. The EMBO Journal [Internet]. 2015 ;34(12):1674 - 1686. Available from: http://onlinelibrary.wiley.com/doi/10.15252/embj.201488795/abstract
 . Midlife personality and risk of Alzheimer disease and distress A 38-year follow-up. Neurology [Internet]. 2014 ;83(17):1538 - 1544. Available from: http://www.neurology.org/content/83/17/1538