Association Between Psychological Distress and Incident Dementia in a Population-Based Cohort in Finland

Abstract

ImportanceSymptoms of psychological distress have shown association with subsequent dementia, but the nature of association remains unclear.ObjectiveTo examine the association of psychological distress with etiological risk of dementia and incidence of dementia in presence of competing risk of death.Design, Setting, and ParticipantsThis cohort study consisted of population-based cross-sectional National FINRISK Study surveys collected in 1972, 1977, 1982, 1987, 1992, 1997, 2002, and 2007 in Finland with register-based follow-up; and the cohort was linked to Finnish Health Register data for dementia and mortality for each participant until December 31, 2017. Participants included individuals without dementia who had complete exposure data. Data were analyzed from May 2019 to April 2022.ExposuresSelf-reported symptoms of psychological distress: stress (more than other people), depressive mood, exhaustion, and nervousness (often, sometimes, never).Main Outcomes and MeasuresIncident all-cause dementia, ascertained through linkage to national health registers. Poisson cause-specific hazard model (emphasizing etiological risk) and Fine–Gray subdistribution hazard model (emphasizing effect on incidence) considering dementia and death without dementia as competing risks. Covariates of age, sex, baseline year, follow-up time, educational level, body mass index, smoking, diabetes, systolic blood pressure, cholesterol, and physical activity. Sensitivity analysis was performed to reduce reverse causation bias by excluding individuals with follow-up less than 10 years.ResultsAmong 67 688 participants (34 968 [51.7%] women; age range, 25 to 74 years; mean [SD] age, 45.4 years), 7935 received a diagnosis of dementia over a mean follow-up of 25.4 years (range, 10 to 45 years). Psychological distress was significantly associated with all-cause dementia in a multivariable Poisson model, with incidence rate ratios from 1.17 (95% CI, 1.08-1.26) for exhaustion to 1.24 (95% CI, 1.11-1.38) for stress, and remained significant in sensitivity analyses. A Fine–Gray model showed significant associations (with hazard ratios from 1.08 [95% CI, 1.01-1.17] for exhaustion to 1.12 [95% CI, 1.00-1.25] for stress) for symptoms other than depressive mood (hazard ratio, 1.08 [95% CI, 0.98-1.20]). All the symptoms showed significant associations with competing risk of death in both models.Conclusions and RelevanceIn this cohort study, psychological distress symptoms were significantly associated with increased risk of all-cause dementia in the model emphasizing etiological risk. Associations with real incidence of dementia were diminished by the competing risk of death.

Physical frailty, genetic predisposition, and incident dementia: a large prospective cohort study

“…This may be because in the central nervous system, the implementation of these two factors is achieved in areas normally located under the frontal and parietal cortex and in the visuomotor and executive areas of the cortex, which are also associated with the onset of dementia [ 42 – 44 ]. For exhaustion, Sulkava et al reported an HRs of 1.12 (95% CI, 1.00–1.25) in Finland and S. Islamoska et al identified an incidence rate ratio of 1.024 (95% CI, 1.004–1.043) in Copenhagen [ 45 , 46 ]. Weight loss was also identified as an important risk factor of dementia.…”

Stress, Distress, Tensity, Neuroticism, and Risk of Dementia

“…Sulkava et al 2 published their study about the association between psychological distress and incident dementia with a sophisticated analysis of competing risk of death. The findings indicate that stress, depressive mood, nervousness, and exhaustion were associated with a 17% to 24% increased risk of dementia.…”

“…There are fewer studies examining whether anxiety is independently associated with dementia, and this research effort is complicated by studying concepts closely related to anxiety such as stress, distress, neuroticism, and personality style. Especially relevant to understanding the study by Sulkava et al is neuroticism, which can be conceptualized as an abiding tendency toward depression or anxiety in stressful circumstances. The definition of stress or depression in the study by Sulkava et al was based on a self-report answering a question about the prior month.…”

“…Especially relevant to understanding the study by Sulkava et al is neuroticism, which can be conceptualized as an abiding tendency toward depression or anxiety in stressful circumstances. The definition of stress or depression in the study by Sulkava et al was based on a self-report answering a question about the prior month. This negates any possibility of understanding the role of stress as a causative agent in the development of dementia, as no information on either lifelong neurotic-like traits nor about clinically diagnosed anxiety or depression is collected.…”

“…These findings suggest that to solve the conundrum surrounding the association of depression and anxiety with risk of dementia we need to look into enduring patterns of perceiving the internal and external environment over long periods and through phases of our lifecycle. Sulkava et al added an important facet to the field by accounting for competing risk of death. This should become a standard when researching these questions.…”