Stress may increase risk for Alzheimer's disease

Stress promotes neuropathological changes that are also seen in Alzheimer's disease. Scientists from the Max Planck Institute of Psychiatry in Munich have discovered that the increased release of stress hormones in rats leads to generation of abnormally phosphorylated tau protein in the brain and ultimately, memory loss.

Protein deposits in are a typical feature of : the excessive alteration of the tau protein through the addition of phosphate groups – a process known as hyperphosphorylation – causes the protein in the cells to aggregate into clumps. As a result, nerve cells die, particularly in the hippocampus, a part of the that plays an important role in learning and memory, as well as in the prefrontal cortex which regulates higher cognitive functions.

Fewer than ten percent of Alzheimer cases have a genetic basis. The factors that contribute to the rest of the cases are largely unknown. Following up on epidemiological studies, scientists at the Max Planck Institute of Psychiatry hypothesized that adverse life events () may be one trigger of Alzheimer's disease.

In cooperation with colleagues at the University of Minho in Braga, Portugal, the Munich-based researchers have now shown that stress, and the hormones released during stress, can accelerate the development of Alzheimer disease-like biochemical and behavioural pathology. They found increased hyperphosphorylation of tau protein in the hippocampus and prefrontal cortex of rats that has been subjected to stress (e.g. overcrowding, placement on a vibrating platform) for one hour daily over a period of one month. Animals showing these changes in tau also showed deficits in memories that depended on an intact hippocampus; also, animals with abnormally hyperphosphorylated tau were impaired in behavioural flexibility, a function that requires proper functioning of the prefrontal cortex.

These results complement previous demonstrations by the scientists that stress leads to the formation of beta-amyloid, another protein implicated in Alzheimer's disease. "Our findings show that and stress can cause changes in the like those that arise in Alzheimer's disease", explains Osborne Almeida from the Max Planck Institute of Psychiatry.

The next challenge will be to see how applicable the results obtained in animals are to the development of non-familial forms of Alzheimer's disease. "Viewing stress as a trigger of Alzheimer's disease offers exciting new research possibilities aimed at preventing and delaying this severe disease. Moreover, since vulnerability to major depression is known to be increased by stress, it will be interesting to know the role of molecules such as beta-amyloid and tau in the onset and progress of this condition", says Osborne Almeida.

More information: Ioannis Sotiropoulos, Caterina Catania, Lucilia G. Pinto, Rui Silva, G. Elizabeth Pollerberg, Akihiko Takashima, Nuno Sousa, and Osborne F. X. Almeida, Stress Acts Cumulatively to Precipitate Alzheimer's Disease-Like Tau Pathology and Cognitive Deficits, Journal of Neuroscience, May 25, 2011; 31(21):7840-7847

Related Stories

Diabetes drug could work against Alzheimer's

Nov 24, 2010

Scientists from Berlin, Bonn and Dundee show in animal models that the diabetes drug metformin has an effect against one of the main causes of the Alzheimer's disease.

Chronic high cholesterol diet produces brain damage

Nov 24, 2010

Research from the Laboratory of Psychiatry and Experimental Alzheimers Research at the Medical University Innsbruck (Austria) demonstrated that chronic high fat cholesterol diet in rats exhibited pathologies similar to Alzheimer's ...

Recommended for you

Recorded Ebola deaths top 7,000

12 hours ago

The worst Ebola outbreak on record has now killed more than 7,000 people, with many of the latest deaths reported in Sierra Leone, the World Health Organization said as United Nations Secretary-General Ban ...

Liberia holds Senate vote amid Ebola fears (Update)

16 hours ago

Health workers manned polling stations across Liberia on Saturday as voters cast their ballots in a twice-delayed Senate election that has been criticized for its potential to spread the deadly Ebola disease.

Evidence-based recs issued for systemic care in psoriasis

Dec 19, 2014

(HealthDay)—For appropriately selected patients with psoriasis, combining biologics with other systemic treatments, including phototherapy, oral medications, or other biologic, may result in greater efficacy ...

Bacteria in caramel apples kills at least four in US

Dec 19, 2014

A listeria outbreak believed to originate from commercially packaged caramel apples has killed at least four people in the United States and sickened 28 people since November, officials said Friday.

Steroid-based treatment may answer needs of pediatric EoE patients

Dec 19, 2014

A new formulation of oral budesonide suspension, a steroid-based treatment, is safe and effective in treating pediatric patients with eosinophilic esophagitis (EoE), according to a new study in Clinical Gastroenterology and Hepatology, the official clinical practice journal ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.