Time and Perspective Affects Disease Trajectory in MDD, Anxiety

The disease trajectories of major depressive disorder (MDD) and anxiety disorder in the general population depends on the length of follow-up and definition of disease, according to study results published in Journal of Affective Disorders.

Researchers conducted a cohort study (The Netherlands Mental Health Survey and Incidence Study-2) that recruited participants from the general Dutch population between 2007 and 2009. Participants underwent interviews at baseline, 3 years, 6 years, and 9 years, respectively, to evaluate mental health conditions.

For this analysis, individuals with MDD (n=208), anxiety disorder (n=220), or both conditions (n=69) at baseline were assessed for trends in recovery or persistence of symptoms. A narrow perspective of disease was defined as considering only the presence of the index disorder and a broad perspective was defined as considering any mood, anxiety, or substance use disorder.

Study cohorts comprised 67.3% to 72.5% women with a mean age of 42.5 to 44.5 years at baseline. Of the study participants, 55.6% to 64.7% had any childhood abuse, 46.4% to 51.0% had parental psychopathology, 43.1% to 45.9% had any chronic physical disorder, 23.2% to 58.8% used psychotropic medications, and 29.2% to 48.5% used specialized medical health care, respectively.

The length of follow-up affected the course of disease, in which the recovery rate of MDD at 3 years was 74.0% compared with 51.9% at 9 years. In general, recovery rates for anxiety disorder were higher than for MDD.

Using a narrow or broad perspective, 51.9% and 35.6% of the MDD group had an early remission 9-year trajectory, 16.8% and 20.7% had a late remission trajectory, 26.4% and 29.8% a recurrent trajectory, and 4.8% and 13.9% persistent trajectory, respectively. Similar trends were observed for the anxiety disorder and both MDD and anxiety disorder cohorts, in which a narrow perspective overestimated early remission trajectories and underestimated persistent trajectories compared with the broad perspective.

The major limitation of this study is that anxiety disorder subgroups cannot be evaluated due to insufficient power.

Study authors concluded, “This study shows that using the narrow perspective, the recovery rates of both MDD and anxiety disorder reduced by a third and a quarter respectively (from 74.0% to 51.9% and from 79.5% to 59.1%) when the perspective switched from short to long term. Despite this decline, most people with MDD or anxiety disorder had a rather favorable prognosis when this narrow perspective is applied. However, the recovery rates of both MDD and anxiety disorder reduced by half when the perspective switched from short follow-up and narrow definition of disease course (MDD: 74.0%; anxiety disorder: 79.5%) to long follow-up and broad definition of disease course (35.6% and 40.0% respectively), resulting in far less optimistic views on disease prognosis.”