Objective To study the relation among psychosocial stressors, long-standing distress and incidence of dementia, in a sample of women followed from midlife to late life.

Design Prospective longitudinal population study.

Setting The analyses originate from the prospective population study of women in Gothenburg, Sweden, a representative sample of women examined in 1968 (participation rate 90%) and re-examined in 1974, 1980, 1992, 2000 and 2005.

Participants 800 women born in 1914, 1918, 1922 and 1930 who were systematically selected for a psychiatric examination at baseline, in 1968.

Primary and secondary outcome measures 18 psychosocial stressors (eg, divorce, widowhood, work problems and illness in relative) were obtained at baseline. Symptoms of distress were measured according to a standardised question at each study wave. Dementia was diagnosed according to Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria based on information from neuropsychiatric examinations, informant interviews, hospital records, and registry data, and measured through the whole study period.

Results During the 37 years of follow-up, 153 women developed dementia (104 of those had Alzheimer's disease (AD)). Number of psychosocial stressors in 1968 was associated (HR, 95% CI) with higher incidence of dementia (1.15, 1.04 to 1.27) and AD (1.20, 1.07 to 1.35) between 1968 and 2005, in multivariate Cox regressions. Number of psychosocial stressors in 1968 was also associated (OR, 95% CI) with distress in 1968 (1.48, 1.32 to 1.67), 1974 (1.31, 1.17 to 1.46), 1980 (1.27, 1.11 to 1.45), 2000 (1.39, 1.14 to 1.70) and 2005 (1.35, 1.02 to 1.79), in multivariate logistic regressions. Number of psychosocial stressors (HR 1.17, 95% CI 1.03 to 1.33) and long-standing distress (1968–1974–1980) (HR 1.58, 95% CI 1.03 to 2.45) were independently associated with AD.

Conclusions Our study shows that common psychosocial stressors may have severe and long-standing physiological and psychological consequences. However, more studies are needed to confirm these results and investigate whether more interventions such as stress management and behavioural therapy should be initiated in individuals who have experienced psychosocial stressors.