Changes in Prevalence of Depressive Symptoms in Alameda County

Abstract

Trends in depression are examined using data from the Alameda County Study, a three-wave, prospective community survey covering an 18-year period (1965-1974-1983). Age-period-cohort effects in rates of depressive symptoms were analyzed using logistic regression procedures to adjust for attrition due to loss-to-follow-up and nonresponse. The results indicate the presence of all three effects. There was a marked period effect, with rates in 1974 significantly higher than in either 1965 or 1983. There also was a definite cohort effect, with older cohorts exhibiting higher rates of depressive symptoms than younger cohorts. These findings do not provide support for an "age of melancholia" nor for an increasing cohort effect in succeeding generations. These prospective data on depressive symptoms are contrasted with those from studies that use cross-sectional data to estimate temporal trends in clinical depression, employing retrospective reports of lifetime prevalence and discussing possible reasons for the disparate findings.

Gender differences in the age-cohort distribution of psychological distress in Canadian adults: findings from a national longitudinal survey

“…Several authors have hypothesized that the age distribution observed for psychological distress may be confounded by a cohort effect (Brault et al 2011;Chiao et al 2009;Kasen et al 2003;Jorm 2000;Lewinsohn et al 1993;Mirowsky and Kim 2007;Roberts et al 1991;Sacker and Wiggins 2002;Yang 2007). Thus, for instance, young adults might express a higher mean level of distress than older adults not only because they are exposed to more risk factors or because they are more vulnerable to those risk factors, but, at least partly, because they were born at a time when these factors were more prevalent or potentially more harmful.…”

“…However, that study did find higher prevalences for those aged 62 years and older (in 1965), 70 years and older (in 1974) and 80 years and older (in 1983). According to Roberts et al (1991), the variation in peak depression prevalence among seniors between 1965 and 1983 could indicate that the age distribution observed in other studies is biased by a cohort effect.…”

“…The mean level of depressive symptoms tends to be higher among young adults, then diminishes until the forties (Mirowsky and Kim 2007), mid-fifties (Kessler et al 1992) or sixties (Schieman et al 2001) before again increasing among those aged 70 and older. Roberts et al (1991) compared the prevalence of depression by age in 1965, 1974 and 1983 and found no statistically significant differences between young and middle-aged adults. However, that study did find higher prevalences for those aged 62 years and older (in 1965), 70 years and older (in 1974) and 80 years and older (in 1983).…”

“…An alternative explanation for the distribution of psychological distress by age is the cohort effect (Brault et al 2011;Chiao et al 2009;Kasen et al 2003;Jorm 2000;Lewinsohn et al 1993;Mirowsky and Kim 2007;Roberts et al 1991;Sacker and Wiggins 2002;Yang 2007). The cohort effect results from generational exposure to unique combinations of social and cultural factors, which differentiate each birth cohort from previous and subsequent generations (Susser et al 2006).…”

“…The age and cohort effects and their interaction have also been investigated for depression and depressive symptoms (Brault et al 2011;Chiao et al 2009;Kasen et al 2003;Lewinsohn et al 1993;Mirowsky and Kim 2007;Roberts et al 1991;Yang 2007). But only the study conducted by Brault et al (2011) covers a broad age range and includes several waves of data collection.…”