Age, period, and cohort effects in psychological distress in the United States and Canada

Abstract

Although treatment utilization for depression and anxiety symptoms has increased substantially in the United States and elsewhere, it remains unclear whether the underlying population distribution of psychological distress is changing over time. We estimated age, period, and cohort effects using data from 2 countries over more than 20 years, including National Health Interview Surveys from 1997 to 2010 (n = 447,058) and Canadian Community Health Surveys from 2000 to 2007 (n = 125,306). Psychological distress was measured with the Kessler Psychological Distress Scale. By period, both countries showed the highest levels of psychological distress in 2001 and the lowest levels in 2007. By age, psychological distress was highest in adolescence and during the late 40s and early 50s. By cohort, Canadian Community Health Survey results indicated a decreasing cohort effect among those born in 1922-1925 through 1935-1939 (β = -0.36, 95% confidence interval: -0.45, -0.27) and then a continuously increasing cohort effect during the remainder of the 20th century through 1989-1992 (β = 0.49, 95% confidence interval: 0.38, 0.61). The National Health Interview Survey data captured earlier-born cohorts and indicated an increased cohort effect for the earliest born (for 1912-1914, β = 0.44, 95% confidence interval: 0.26, 0.61). In sum, individuals in the oldest and more recently born birth cohorts have higher mean psychological distress symptoms compared with those born in midcentury, underscoring the importance of a broad, population-level lens for conceptualizing mental health.

Keywords: Canada; Canadian Community Health Surveys; National Health Interview Surveys; United States; age-period-cohort effects; anxiety; depression; psychological distress.

Figure 1.

A) Age, B) period, and C) cohort effects in psychological distress in the Canadian general population (n = 126,306), 2000–2007, and the US general population (n = 447,058), 1997–2011. The intrinsic estimator (IE) estimate is the mean change in psychological distress associated with a particular age-period-cohort group relative to the mean for all age-period-cohort groups combined. CCHS, Canadian Community Health Survey; NHIS, National Health Interview Survey. Solid lines, IE estimates; dotted lines, 95% confidence intervals.

Figure 2.

A) Age, B) period, and C) cohort effects in psychological distress in the Canadian male population (n = 57,161), 2000–2007, and the US male population (n = 195,636) 1997–2011. The intrinsic estimator (IE) estimate is the mean change in psychological distress associated with a particular age-period-cohort group relative to the mean for all age-period-cohort groups combined. CCHS, Canadian Community Health Survey; NHIS, National Health Interview Survey. Solid lines, IE estimates; dotted lines, 95% confidence intervals.

Figure 3.

A) Age, B) period, and C) cohort effects in psychological distress in the Canadian female population (n = 69,145), 2000–2007, and the US female population (n = 251,422), 1997–2011. The intrinsic estimator (IE) estimate is the mean change in psychological distress associated with a particular age-period-cohort group relative to the mean for all age-period-cohort groups combined. CCHS, Canadian Community Health Survey; NHIS, National Health Interview Survey. Solid lines, IE estimates; dotted lines, 95% confidence intervals.

Figure 4.

A) Age, B) period, and C) cohort effects in psychological distress in the Canadian population with lower household educational attainment (n = 78,629), 2000–2007, and the US population with lower household educational attainment (n = 145,919), 1997–2011. The intrinsic estimator (IE) estimate is the mean change in psychological distress associated with a particular age-period-cohort group relative to the mean for all age-period-cohort groups combined. CCHS, Canadian Community Health Survey; NHIS, National Health Interview Survey. Solid lines, IE estimates; dotted lines, 95% confidence intervals.

Figure 5.

A) Age, B) period, and C) cohort effects in psychological distress in the Canadian population with higher household educational attainment (n = 41,405), 2000–2007, and the US population with higher household educational attainment (n = 86,007), 1997–2011. The intrinsic estimator (IE) estimate is the mean change in psychological distress associated with a particular age-period-cohort group relative to the mean for all age-period-cohort groups combined. CCHS, Canadian Community Health Survey; NHIS, National Health Interview Survey. Solid lines, IE estimates; dotted lines, 95% confidence intervals.