Depression, anxiety disorders, alcohol dependence and marijuana dependence affect roughly twice as many people as had previously been estimated, a new study finds. Nearly 60 percent of the population experiences at least one of these mental disorders by age 32, say study directors and psychologists Terrie Moffitt and Avshalom Caspi, both of Duke University in Durham, N.C. . . .
[I]ndividuals who report past mental disorders in surveys display an increased likelihood of developing such ailments in the future. . . .
Half of the people diagnosed in the new study had a mental disorder for a relatively short period or in a single episode. Moffitt nonetheless regards these cases as serious, since short-term symptoms often led to work problems, efforts to get mental-health care or suicide attempts. . . .
Among 32-year-old New Zealanders, Moffitt and her colleagues find lifetime prevalence rates of 50 percent for anxiety disorders, 41 percent for depression, 32 percent for alcohol dependence and 18 percent for marijuana dependence. Participants who developed one of these disorders tended to experience others as well, including less-common ones such as eating disorders.
Self-report surveys in the United States . . . and New Zealand have found lifetime prevalence rates for common mental disorders that are about half as large as those in the new investigation.
A long-term study of 1,400 North Carolina children tracked into young adulthood finds rates of mental disorders comparable to those reported by Moffitt’s team, according to Duke psychologist and study director Jane Costello. Those data have yet to be published.
Prevalence rates for mental health issues are a controversial topic because the diagnostic thresholds for mental illness are fuzzy. Are rates mostly a product of diagnostic practices and definitions which change over time? What is the boundary between variations within the normal, non-pathological range and a genuine mental illness? Is it just a big scam to increase mental health drug prescriptions?
Almost everybody suffers from a physical illness or traumatic injury at some point in life, so a high lifetime prevalence for mental illness really shouldn't be so shocking by comparison. But, there is a tendency to see all mental health issues as chronic.
Put another way, we tend to see mental health issues not as illnesses, but as disabilities. A disability rate of 60% seems quite high relative to physical disability rates (about 12.8% for adults aged 21-64 in the United States).
Certainly, many of the most striking and most studies mental health issues, schizophrenia and bipolar disorder, for example, are normally life long, treatable but incurable disabilities. This is one of the reason that the health insurance model, designed to cover severe incidents of poor health that are not foreseen in the case of an individual, but have a statistically predictable prevalence, is such a poor fit for these conditions. Indeed, the persistence of a mental illness over a prolonged period of time is part of the definition of some mental health conditions.
There is also a tendency to see even conditions which are not inevitable, as subject to strong dispositions. For example, someone strongly predisposed to alcohol dependency, may never develop alcohol dependency if they grow up in an overwhelmingly Islamic or Mormon environment where alcohol isn't as available. Someone strongly predisposed to be phobic of snakes may never discover this fact if they grow up in Ireland or Iceland.
In contrast, very few physical health conditions are defined by how long they have persisted, and many commonly treated conditions are not chronic, even if they recur frequently. About 25% of people in the U.S. get the flu in any given year. Many people get the flu every few years. Getting the flu in prior years is probably a good predictor of your likelihood to get it in future years. But, while someone who suffers from clinical depression every few years might be classified as "depressive" and having a chronic disability, few people would see the repeat flu victim that way.
Also complicating the analysis is the fact that the classification of alcohol dependence and marijuana dependence as mental health conditions rather than moral failings and poor choices, is controversial. In the same vein, major issues exist concerning the proper character of issues like pathological gambling.
Definitional problems are rife in mental health in part, because the underlying biological and psychological causes of mental health issues are often only dimly understood, and in part, because the information is relevant for a variety of reasons that suggest different definitions.
A definition of a mental illness designed for the purpose of tracking genetic inheritance of mental illness, make appropriately include subclinical manifestations that don't impair a person's life because of the kind of life they have chosen to live. A definition of mental illness designed for the purpose of determining who could benefit from treatment, in contrast, might be structured differently.
Perhaps, we need different mental health care systems to respond to chronic and non-chronic but acute conditions.