How depression develops

A novel study published in the current issue of Psychotherapy and Psychosomatics discloses how depression may develop.

To explain the overt heterogeneous nature of major depressive disorder (MDD), it could be valuable to focus on individual symptoms. MDD symptoms differ in their underlying biology, risk factors and psychosocial impairments. In addition, the presence of specific symptoms (e.g. psychomotor agitation) may have important clinical implications, such as expectations regarding the response to antidepressants.

The network approach is a conceptualization that specifically focuses on individual symptoms. According to this approach, psychopathology results from the associations between symptoms, and each of these symptoms may have its unique set of associations with other symptoms. This information can be visualized into a network, in which symptoms are represented as nodes and the associations between them as lines. The present study aimed to test whether symptom centrality was indeed related to the risk of developing MDD.

The Authors selected 501 adults with no lifetime DSM-IV depressive or anxiety disorder from the baseline assessment of the Netherlands Study of Depression and Anxiety (NESDA). Results showed that the risk of developing MDD depends on the type of subthreshold symptom that a person reports. Loss of interest/pleasure, depressed mood, fatigue and concentration problems were the most important risk factors, and these symptoms could, therefore, help clinicians (e.g. general practitioners) in identifying persons who are most vulnerable for MDD. These specific symptoms were also central in the MDD symptom network and may, consequently, be valuable targets in prevention strategies. By eliminating or reducing such a central symptom, it is hypothesized that activity within the whole network can be reduced (or prevented).

In conclusion, subthreshold MDD symptoms were differentially associated with the prospective onset of MDD and these findings demonstrate the value of an approach focusing on individual symptoms. The network approach may be such an approach, as we showed that the risk of developing MDD depended on the centrality of a symptom in the network. This centrality may, therefore, inform clinicians on the symptoms that are likely to have the most prognostic impact when adapted by targeted treatment.