Background
Most information about the lifetime prevalence of mental disorders comes from retrospective surveys, but how much these surveys have undercounted due to recall failure is unknown. We compared results from a prospective study with those from retrospective studies.
Method
The representative 1972–1973 Dunedin New Zealand birth cohort (n=1037) was followed to age 32 years with 96% retention, and compared to the national New Zealand Mental Health Survey (NZMHS) and two US National Comorbidity Surveys (NCS and NCS-R). Measures were research diagnoses of anxiety, depression, alcohol dependence and cannabis dependence from ages 18 to 32 years.
Results
The prevalence of lifetime disorder to age 32 was approximately doubled in prospective as compared to retrospective data for all four disorder types. Moreover, across disorders, prospective measurement yielded a mean past-year-to-lifetime ratio of 38% whereas retrospective measurement yielded higher mean past-year-to-lifetime ratios of 57% (NZMHS, NCS-R) and 65% (NCS).
Conclusions
Prospective longitudinal studies complement retrospective surveys by providing unique information about lifetime prevalence. The experience of at least one episode of DSM-defined disorder during a lifetime may be far more common in the population than previously thought. Research should ask what this means for etiological theory, construct validity of the DSM approach, public perception of stigma, estimates of the burden of disease and public health policy.
Compared with other World Mental Health survey sites New Zealand has relatively high prevalences, although almost always a little lower than for the US. For all disorders, except specific phobia, interference with life was reported to be moderate, on average, which has lead to less than a third of cases being classified as mild. Most people who have ever met full DSM-IV criteria, including the impairment criterion, and who experience symptoms or an episode in the past 12 months find that their disorders impact on their lives to a non-trivial extent.
Māori, and to a lesser extent Pacific people, have a higher prevalence of 12 month mental disorders than Others. Differences are reduced after adjusting for sociodemographic correlates. Relative to need, Pacific people in particular and Māori are less likely than Others to have contact with services (health or non-health), regardless of sociodemographic circumstances.
Compared with other World Mental Health survey sites New Zealand has relatively high prevalences, although almost always a little lower than for the US. For all disorders, except specific phobia, interference with life was reported to be moderate, on average, which has lead to less than a third of cases being classified as mild. Most people who have ever met full DSM-IV criteria, including the impairment criterion, and who experience symptoms or an episode in the past 12 months find that their disorders impact on their lives to a non-trivial extent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.