Untreated Mild Depression Can Persist, Worsen Over Time
By Caroline Cassels
Medscape Medical News
February 11, 2010 — Left untreated, mild depression does not resolve with time and for a significant number of patients will persist and worsen, eventually resulting in a diagnosis of major depressive disorder, new research suggests.
A study conducted by investigators at Columbia University Medical Center, New York, showed that 62% of primary care patients who screened positive for mild depressive symptoms at baseline and who had not received any mental health treatment during the past year met criteria for major depression at 4-year follow-up.
"Our findings indicate that simple screening procedures, especially for major depression, can identify primary care patients with milder symptoms that are nevertheless persistent and enduring mental health problems," the study authors, led by Myrna M. Weissman, PhD, write.
The study is published in the February issue of Psychiatric Services.
The investigators note that although screening for psychiatric disorders has gained acceptance in some general medical settings, critics argue about its value. According to the study authors, cross-sectional and short-term follow-up studies comparing patients with undetected depression with those with identified depression suggest that undetected depression tends to be milder and often resolves without intervention.
However, they note that there is a need to better understand the long-term course of untreated patients with mild depressive symptoms.
To determine the clinical utility of screening and look at long-term outcomes in such patients, the researchers conducted a long-term follow-up of patients who screened positive for common psychiatric disorders but who were initially not in treatment.
The cohort included 348 low-income, adult, primary care patients who were screened for major depression, bipolar disorder, anxiety, and substance use disorders at baseline and then reassessed after a mean of 3.7 years by a clinician masked to the results of the initial screen. None of the subjects had received psychiatric care in the year before initial screening.
The study showed that of 39 individuals with depressive symptoms at baseline, 62% of them had major depressive disorder at follow-up.
Other indicators also pointed to a less than benign course for these patients. When researchers measured social functioning at the follow-up interview, they found that patients who had depressive symptoms at baseline had significantly worse function than their counterparts who screened negative at study outset.
For instance, patients who screened positive were more than 6 times as likely to report having made 1 or more visits to a psychiatric emergency department in the year before the follow-up interview. Additional analyses by the researchers showed that a positive baseline screen for depression predicted an alcohol or drug use disorder at follow-up and patients' report of poor or fair emotional or physical health.
"These findings come in the wake of intensive focus by the media on a study reported in January, which showed that depressed patients with mild symptoms did not do any better with medication than with placebo, suggesting that patients with mild depression don’t need treatment," Dr. Weissman said in a statement.
"Of course, patients in a clinical trial are receiving a considerable amount of attention and are not untreated. Our findings suggest that mildly depressed untreated patients do not have a benign course of illness."
The study was supported by the National Institute of Mental Health, GlaxoSmithKline, and Eli Lilly Company. Study author Daniel J. Pilowsky, MD, MPH, reports receiving speaker fees from Astra Zeneca. Mark Olfson, MD, MPH, reports he has received support from or has served as a consultant for AstraZeneca, Bristol-Myers Squibb, Eli Lilly & Company, Janssen, McNeil Pharmaceuticals, and Pfizer. The other study authors have disclosed no relevant financial relationships.
