Psychological Medicine

Original Articles

Secular trends in the prevalence of dementia and depression in Swedish septuagenarians 1976–2006

P. Wiberga1, M. Waerna1, E. Billstedta1, S. Östlinga1 and I. Skooga1 c1

a1 Neuropsychiatric Epidemiology Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at Göteborg University, Göteborg, Sweden


Background It is not clear whether the prevalence of dementia and depression among the elderly has changed during the past 30 years.

Method Population-based samples from Gothenburg, Sweden were examined with identical psychiatric and neuropsychiatric examinations at age 70 years in 1976–1977 (n = 404, response rate 78.8%) and 2000–2001 (n = 579, response rate 66.4%), and at age 75 in 1976–1977 (n = 303, response rate 78%) and 2005–2006 (n = 753, response rate 63.4%). Depression was diagnosed according to DSM-IV and dementia according to Kay's criteria. General linear models (GLMs) were used to test for differences between groups.

Results Dementia was related to age but not to birth cohort or sex. Major depression was related to sex (higher in women) but not to birth cohort or age. Minor depression was related to birth cohort, sex (higher in women), age (higher at age 75) and the interaction effect of birth cohort × age; that is, the prevalence of minor depression increased with age in the 2000s but not in the 1970s. Thus, the prevalence of minor depression was higher in 2005–2006 than in 1976–1977 among 75-year-olds for both men (12.4% v. 3.7%) and women (19.1% v. 5.6%) whereas there were no birth cohort differences at age 70.

Conclusions Secular changes were observed only for minor depression, which is considered to be related more to psychosocial factors than major depression. The high prevalence of minor depression in later-born birth cohorts emphasizes the importance of detecting minor depression in the elderly.

(Received December 05 2011)

(Revised January 24 2013)

(Accepted January 31 2013)

(Online publication March 12 2013)

Key words

  • Birth cohort;
  • dementia;
  • depression;
  • population study;
  • secular trends


c1 Address for correspondence: I. Skoog, M.D., Ph.D., Neuropsychiatric Epidemiology Unit, Neuropsykiatri SU/Mölndal, Wallinsgatan 6, SE-431 41 Mölndal, Sweden. (Email: