Depression Symptoms More than a Checklist for Diagnosis

Depression is more than a checklist of symptoms, and should be reconsidered as a complex web of interlocking symptoms, according to findings published in the Journal of Affective Disorders.

Researchers from KU Leuven in Belgium studied depressive symptoms cited from the Inventory of Depressive Symptomalogy (IDS 30) in nearly 3,500 outpatients in order to organize interactive depressive symptoms to examine how each symptom is central to driving the depressive process. The IDS 30 symptoms were categorized and compared to the likeness of the DSM and non-DSM symptoms, defined as those that connect each symptom to all other symptoms.

Some of the 28 specific symptoms were more closely related than others, or “centralized,” which meant they had a bigger impact on the depressive process, the researchers said. Both DSM symptoms, such as sad mood, and non-DSM symptoms, like anxiety, were considered to be the most centralized symptoms. DSM criteria were not more centralized than non-DSM symptoms.

“If you think of depression as a network of interacting symptoms, one symptom can cause another,” the study’s lead author Dr. Eiko Fried explained in a press release. “For instance, insomnia may lead to fatigue, which in turn may cause concentration problems that feed back into insomnia. This example of a vicious circle shows that the specific symptoms patients report, and their interactions, can be of crucial clinical importance.”

Sad mood and decreased interest or pleasure, the two main DSM symptoms were in the top 5 centralized symptoms. Other characteristics of depression from the DSM such as hypersomnia, agitation, and weight change were not any more central than other common symptoms of depression like pessimism and anxiety.

“We need to stop thinking of depression as a disease that causes a number of interchangeable symptoms,” Fried continued. “Depression is a complex, extremely heterogeneous system of interacting symptoms. And some of these symptoms may be far more important than others.”Instead of tallying the number of depressive symptoms a patient has, psychiatrists should take into account which of the symptoms a patient expresses before diagnosing a patient with depression, the researchers added.

“Ideally, the list of depression symptoms should become more comprehensive to do justice to the heterogeneity of depression,” Fried concluded. “I also think both clinicians and researchers can learn a lot from paying more attention to individual symptoms and their interactions. But of course, we need much more research before we can actually replace the DSM diagnosis of depression with something else.”