Epidemiology of major depressive disorder: results from the National Epidemiologic Survey on Alcoholism and Related Conditions.
Hasin DS, Goodwin RD, Stinson FS and Grant BF;
Commented by , 22 Nov 2005
Background
It is debated whether the high prevalence rates of major depression found in early epidemiological studies from the 80's and early 90's reflect true findings. The DSM-IV includes a criterion of clinical significance that should be fulfilled to qualify for a disorder on the syndromal level, i.e. that symptoms should cause clinically significant distress or impairment in social occupational or other important areas of functioning. However, such a criterion was not included in prior large scale epidemiological studies and it may be that a proportion of the depressive conditions may have represented brief fluctuations in well-being due to mild distress.
Method
Through 2001 and 2002 a face to face interview was conducted by laymen in a representative sample of citizens aged 18 years or older in the United States including 43,093 responders and with a response rate of 81%. Subjects were interviewed with the Alcohol Use Disorder and Associated Disabilities Interview Schedule - DSM-IV version.
The interview includes two questions on distress and six on impact of the disorder. Furthermore, the interview includes specific questions on the chronological relationship between the depressive syndrome and any substance or medical induced syndrome aiming to distinguish between primary and secondary depressive syndromes.
Results
The 12-month prevalence of Major Depressive Disorder (MDD) was 5.3% (3.6% for men and 6.9% for women) and the lifetime prevalence of Major Depressive Disorder was 13.3% (9.0% for men and 17.1% for women).
The prevalence was highest for younger subjects aged 18-29 years and lowest for subjects aged 65 years or more. Subjects, who were widowed, separated or divorced had higher rates as had subjects who had never married.
The prevalence decreased with increasing personal income but no relationship was found to educational level or urbanicity. Mean age at onset was 30.4 years, the median duration of the longest depressive episode was 24 weeks and responders reported a mean of 4.7 depressive episodes.
Nearly half wanted to die, over a third thought of suicide and 9% reported a suicide attempt. Psychiatric comorbidity was frequent with 38% suffering from a personality disorder, 36% from an anxiety disorder and 14% from an alcohol use disorder during 12 months. Approximately 60% of subjects with MDD reported treatment for the disorder, less likely for men.
Professor Kessing's comments
The study confirms the prior findings of a high 12-month and lifetime prevalence of MDD including a criterion of clinical significance. It seems that the depressive disorders were of a rather severe clinical significance with a long duration of episodes, frequent suicidal thoughts, frequent psychiatric comorbidity and a high risk of recurrence.
Despite suffering from a serious disorder, 40% of the responders did not report that they had received any specific treatment for the disorder. Still, we do not have any clear sense of the nature and clinical presentation of the depressive syndromes. E.g., how large a proportion of the subjects presented with somatic symptoms such as sleep and appetite disturbances etc.?
Further, it would be interesting to know how large a proportion of the depressive syndromes responded to antidepressant pharmacological treatment. As the present study is ongoing, some of these questions may be answered in future follow-ups