Psychiatric disorders do not increase the risk of Alzheimer’s disease, a new study shows. However, the prevalence of psychiatric diagnoses increased before the Alzheimer’s diagnosis, which might be due to prodromal symptoms of Alzheimer’s disease. The results were published in European Psychiatry.

History of mood disorder, such as depression, or any psychiatric disorder were associated with a higher risk of Alzheimer’s disease when psychiatric disorders that occurred at least five years before the Alzheimer’s diagnosis were taken into account. However, the associations disappeared when this time window was extended to 10 years. The exponential increase in the prevalence of psychiatric disorders before the diagnosis implies that some of these psychiatric disorders might actually have been prodromal symptoms of Alzheimer’s disease. This underlines the importance of proper differential diagnostics of Alzheimer’s disease. Further, the findings also highlight the importance of using an appropriate time window when assessing the risk factors of neurodegenerative diseases with a long onset period. Otherwise the identified “risk factors” may actually be manifestations of the neurodegenerative disease.

Although psychiatric disorders diagnosed 10-40 years before Alzheimer’s disease were not related to a higher risk, the life expectancy of persons with psychiatric disorders was, and is still decreased. Thus, those persons with psychiatric disorders who lived long enough to develop Alzheimer’s disease were a selected sample of all persons with psychiatric disorders.

Paper: “Hospital-treated mental and behavioral disorders and risk of Alzheimer’s disease: A nationwide nested case-control study”
Reprinted from materials provided by the University of Eastern Finland.

június 20, 2017