According to a recently completed study, the risk of dementia is one-fifth higher in people who report more perceived stress or depression, nervousness or exhaustion.
A new population-based study demonstrates that psychological symptoms in middle age increase the risk of developing dementia in old age. The study was carried out collaboratively by the Finnish Institute for Health and Welfare, the University of Helsinki and the University of Eastern Finland. It is the largest study focused on self-reported psychological symptoms so far.
Increasingly reliable results with a new research design
The development of memory disorders is a gradual process affected by a number of factors at different stages of life.
Diagnosis of depressive disorder is considered a risk factor for dementia. Prior research has suggested that even milder symptoms of psychological distress increase the dementia risk. However, these studies have included either a small cohort of patients with dementia or a short follow-up period. Consequently, the studies have been unable to reliably distinguish between actual risk factors and the prodromal symptoms caused by changes in brain that develop before the clinical diagnosis of memory disorder. The new findings published in the JAMA Network Open journal indicate that psychological distress symptoms increase the risk of dementia. This does not appear to be explained by the prodromal symptoms of memory disorders.
It was found that symptoms of depression, exhaustion or nervousness reported even as early as 45 years of age had a significant association with to a subsequent risk of dementia.
The study encompassed approximately 68,000 Finns who participated in the National FINRISK study from 1972 to 2007. They were followed for several decades (10 to 45 years) for dementia diagnoses. Data on dementia were obtained from healthcare registries. When answering the questions pertaining to psychological symptoms, the study subjects were between 25 and 75 years of age.
“In the analyses, we considered deaths with causes other than dementia, something only a handful of dementia researchers have previously done. Those who die younger never have the time to develop dementia, which usually occurs only in older age. We used statistical models that take mortality into account as a competing risk of death,” says Sonja Sulkava, principal investigator for the study.
“As the population ages, memory disorders are becoming more common. Naturally, this makes understanding their risk factors important. From the perspective of psychiatry, it’s particularly interesting that, through careful modelling, we established a connection between symptoms associated with mental distress and an organic brain disease,” says Professor Tiina Paunio from the University of Helsinki.
JAMA Network Open