Mental Disorders Substantially Underestimated in Adults

Deborah Brauser

January 14, 2014

The number of middle-aged and older adults who have psychiatric disorders is substantially and consistently under-reported, especially when compared with physical disorders, new research suggests.

An analysis of more than 1000 adult participants from the Baltimore Epidemiologic Catchment Area (ECA) study, which included interviews going back 24 years, showed that those who had reported a mental disorder in previous assessments under-reported by 2- to 12-fold this information at later recall.

On the other hand, this patient population provided much more accurate recall of physical disorders, such as diabetes, hypertension, and arthritis.

"The take-away is that lifetime estimates based on [participant] recall in cross-sectional surveys underestimate the occurrences of mental disorders," senior author Ramin Mojtabai, MD, PhD, from the Department of Mental Health at Johns Hopkins University in Baltimore, Maryland, said in a release.

The investigators add that although further studies are needed, their findings "raise questions about the accuracy" of general population surveys. Instead, cumulative reports may be the best way to determine true lifetime prevalence.

The study was published online January 8 in JAMA Psychiatry.

Estimate Differences

The researchers evaluated data from 1071 participants (63% women; 62% white, 35% black) from the Baltimore ECA Follow-up study.

Four waves of interviews were conducted with these participants in 1981 (mean age, 35.4 years), 1982, 1996, and 2004/2005 (mean age, 58.9 years) using the Diagnostic Interview Schedule.

During the first 2 interview waves, psychiatric disorders were diagnosed on the basis of criteria from the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-III). The latter 2 waves used criteria from the manual's revised version (DSM-III-R).

Results showed that the lifetime estimate of major depressive disorder (MDD), provided retrospectively at the fourth/last wave of interviews, was 4.5% vs 13.1% for the participants' cumulative evaluations.

In addition, the retrospective estimates vs cumulative evaluations were 0.6% vs 7.1%, respectively, for obsessive-compulsive disorder; 12.6% vs 25.3% for social phobia; 2.5% vs 6.7% for panic disorder; 9.1% vs 25.9% for alcohol abuse or dependence; and 6.7% vs 17.6% for drug abuse or dependence.

"The ratios of wave 4 lifetime prevalence estimates to cumulative prevalence estimates ranged from 2 to 12, indicating 2- to 12-fold differences among the 2 estimates," report the researchers.

Greater Recall Failures for Older Patients

When asked about physical disorders during the fourth wave interview, the participants provided histories that more closely matched past cumulative assessments in all 5 categories discussed. This included diabetes (18.2% vs 20.2%, respectively), hypertension (48.4% vs 55.4%), arthritis (45.8% vs 54%), stroke (5.5% vs 7.2%), and any type of cancer (8.4% vs 10.5%).

The ratios of lifetime prevalence to cumulative prevalence for physical illnesses only ranged from 1.1 to 1.3.

Finally, the participants who were older than 59 years had significantly greater odds than those who were younger than 50 of failing to recall a previously reported history of MDD (odds ratio [OR], 6.69; 95% confidence interval [CI], 1.54 - 29.06), panic disorder (OR, 14.42; 95% CI, 1.96 - 106.36), alcohol abuse or dependence (OR, 16.41; 95% CI, 5.56 - 48.48), and drug abuse or dependence (OR, 22.64; 95% CI, 2.20 - 232.96; all, P < .05).

"The population burden of mental disorders may…be substantially higher than previously appreciated," write the investigators.

Dr. Motjabai noted that the contrast between the retrospective recall of mental disorders vs physical disorders may be due to differences in age at onset, as well as the fluctuating course of psychiatric disorders.

"Stigma associated with mental disorders…might partly explain the discrepancies," he said. "Mental disorders start earlier and have a higher prevalence in early to mid-life, whereas physical disorders are typically illnesses of middle and older age and tend to be chronic."

The researchers add that another explanation could be that symptom criteria were used to ascertain mental disorders, whereas physical illness was ascertained from a participant's report of presence or absence of a particular physical disorder.

Multiple Assessments Needed

Wilson M. Compton, MD, MPE, and Marsha F. Lopez, PhD, MHS, both from the National Institute on Drug Abuse (NIDA) in Bethesda, Maryland, write in an accompanying editorial that they congratulate the investigators "on identifying an important limitation in survey methods as applied to psychiatric illnesses."

They note that multiple assessments may be the best way to collect accurate data at this time.

"The more we learn about psychiatric conditions, the greater the need is for external validators and endophenotypes," write the editorialists.

"Only when we know the underlying markers of disease and enhance clinical appraisal with genetic or neuroscience measures will we be able to completely accurately understand the prevalence of these conditions," they add.

"Until such a day when these markers and measures are available, we will rely on multiple sources of information that triangulate on results as the next best alternative for confirming our insights and improving our knowledge."

Although the research was funded by a grant from NIDA, the investigators report that the organization played no role in the study, including its design, management, and review. The study authors and Dr. Lopez have reported no relevant financial relationships. Dr. Compton reports having stock holdings in Pfizer, General Electric, and 3M.

JAMA Psychiatry. Published online January 8, 2014. Abstract, Editorial

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