Among psychiatry’s critics, the notion that there is an “epidemic” of mental illness in the U.S. is one of the most widely-held beliefs. More radical versions of this narrative implicate psychiatrists and psychiatric medication for the alleged proliferation of mental illness –essentially claiming that psychiatrists are worsening the very illnesses they purport to treat. But what is the evidence for such an “epidemic” of mental illness, in the first place?
In medical science, an “epidemic” usually refers to an infectious disease that has spread rapidly to many people—witness, for example, the recent Ebola epidemic. More broadly, an epidemic denotes any illness that appears with a frequency clearly in excess of what is normally expected.
Incidence vs. Prevalence
When we speak of an illness’s frequency, we are usually referring to its incidence and prevalence. Basically, incidence refers to the number of new cases of the illness within a specific period of time.
Prevalence refers to the total number of persons sick with the illness during a particular period—both old and new cases– regardless of when the illness began. So–over the past few decades, has the incidence or prevalence of psychiatric illness reached “epidemic” proportions in the U.S.? At least with respect to the most serious psychiatric illnesses in adults, the answer is no. And recent data suggest this may also be the case in children and adolescents, though our data base is far from ideal.
While many types of psychiatric illness may be “serious,” the term “serious mental illness” (SMI) is defined by the National Institute of Mental Health as a psychiatric disorder “…resulting in serious functional impairment, which substantially interferes with or limits one or more major life activities.”
Although major depressive disorder, bipolar disorder, and schizophrenia are commonly discussed as prime examples of SMI, the NIMH definition could apply to post-traumatic stress disorder (PTSD), anorexia nervosa or any other psychiatric disorder that fits the impairment criteria.
One method of comparing the occurrence of SMI now to years past is via the National Survey on Drug Use and Health (NSDUH)–an annual nationwide survey involving interviews with approximately 70,000 randomly selected individuals aged 12 and older. NSDUH data over the past decade shows, overall, very little change in rates of SMI in this country.
Data Shows Decline
For example, in 2013, there were an estimated 10.0 million adults aged 18 or older in the United States with SMI in the past year—representing 4.2 percent of the adult population. This number compares with 5.0% in 2010 and 4.8% in 2009. And if we go back to the NSDUH data from 2002, we find that 8.3% of adults in the U.S. were found to have serious mental illness during the 12 months prior to being interviewed.
So, if anything, it seems that SMI prevalence in this country has actually declined over the past decade or so. Going back farther, there is no reason to revise this conclusion. For example, using other national survey data, a group of technical experts estimated SMI in 1990 at about 5.4% of the adult population. Taken together, these data do not point to an “epidemic” of serious mental illness in recent decades.
NSDUH studies don’t yield incidence or prevalence rates for specific disorders such as schizophrenia, bipolar disorder or major depression. However, other sources of information suggest that the incidence and prevalence of these conditions, word-wide, have remained fairly steady over the past 50 years.
For example, while rates of schizophrenia differ considerably from country to country, a 1997 review found that overall incidence rates appear relatively stable across countries and cultures, over at least a 50-year period. This conclusion doesn’t point to an “epidemic” of schizophrenia, following the introduction of antipsychotic medication in the late 1950s and 60s.
Indeed, if antipsychotic medications actually worsened schizophrenia, we would expect to see substantially rising prevalence rates of schizophrenia over the past five decades—but there is no credible evidence of this happening in the U.S. or worldwide.
This doesn’t mean that everyone with schizophrenia ought to take antipsychotic medications indefinitely. A certain percentage of carefully-selected patients with schizophrenia may be able to do without these drugs, once they are clinically stable. But there is no convincing evidence that antipsychotic medications are driving an “epidemic” of schizophrenia (see the review by Dr. Joseph Pierre).