Psychological distress is a risk factor for dementia

Researchers from the Department of Public Health, University of Copenhagen have, in collaboration with the National Research Centre for the Working Environment, and the Danish Dementia Research Centre, shown that being distressed in late midlife is associated with a higher risk of dementia in later life. The findings contribute to our understanding of psychological distress as an important risk factor that should receive more focus when considering prevention initiatives in relation to later dementia.

Psychological distress can be defined as a state of emotional suffering sometimes accompanied by somatic symptoms. Vital exhaustion is operationalized as feelings of unusual fatigue, increased irritability and demoralization and can be considered an indicator of psychological distress. Vital exhaustion is suggested to be a response to unsolvable problems in individuals' lives, in particular when being incapable of adapting to prolonged exposure to stressors.

The physiological stress response, including cardiovascular changes and excessive production of cortisol over a prolonged period, may serve as the mechanism linking psychological distress with an increased risk of dementia. Sabrina Islamoska, Ph.D. student from the Department of Public Health, University of Copenhagen, has shown a dose-response relation between symptoms of vital exhaustion reported in late midlife and the risk of dementia later in life. Islamoska explains: "For each additional symptom of vital exhaustion, we found that the risk of dementia rose by 2%. Participants reporting 5 to 9 symptoms had a 25% higher risk of dementia than those with no symptoms, while those reporting 10 to 17 symptoms had a 40% higher risk of dementia compared with not having symptoms."

The researchers used survey data from 6,807 Danish participants from the Copenhagen City Heart Study, who responded to questions about vital exhaustion in 1991-1994. At the time of the survey, the participants were on average 60 years. The survey data were linked to national hospital, mortality and prescription registers in order to identify dementia cases. The participants were followed until the end of 2016.

Based on the results of this study, Islamoska has drawn attention to the debate on whether psychological distress in late midlife may be important for one's later risk of dementia. Nevertheless, it is also possible that dementia pathology in an early stage result in more psychological distress.

"We were particularly concerned whether the symptoms of vital exhaustion would be an early sign of dementia. Yet, we found an association of the same magnitude even when separating the reporting of vital exhaustion and the dementia diagnoses with up to 20 years," Islamoska said. The results of this study supports that distress in late midlife may potentially increase the risk of dementia in later life. Despite adjusting for several other well-known risk factors for dementia, such as sex, marital status, lower educational level, lifestyle factors and comorbidities, the risk of dementia associated with vital exhaustion did not change.

"Stress can have severe and harmful consequences not just for our brain health, but our health in general. Cardiovascular risk factors are well-known modifiable risk factors for dementia, and in some countries, a stagnation or even a decreasing incidence of dementia has been observed. Our study indicates that we can go further in the prevention of dementia by addressing psychological risk factors for dementia," Islamoska said.