Research Findings Underscore Striking Heterogeneity of Depression
Depression is generally considered to be a specific and consistent disorder characterized by a fixed set of symptoms and often treated with a combination of psychotherapy and medication. However, the standard rating scales used by healthcare professionals and researchers to diagnose this disease often differ in the symptoms they list, perhaps explaining why a one-size-fits-all treatment has to date been so ineffective. This is the finding of research conducted by psychologist Eiko Fried from the University of Amsterdam (UvA). His results are published in the latest edition of the Journal of Affective Disorders.
Depression is often viewed as a common medical disorder like measles – one either has it or one doesn’t. As a result, diagnosis is generally followed by assigning specific treatment options. But unlike physical disorders where blood tests or other objective tests enable a reliable diagnosis, there are no such measures to determine whether someone is depressed. Instead, researchers and clinicians query patients about symptoms that are indicative of depression, such as sadness, suicidal ideation and sleep problems. If a person has many depression symptoms, she is considered depressed.
In his study, Fried used a content analysis to investigate the symptom overlap of 7 rating scales of symptoms that are commonly used in depression research. One of the scales is the Hamilton Rating Scale of Depression, which contains 17 predominantly physical depression symptoms like paralysis, weight loss and psychomotor retardation. Another is the Beck Depression Inventory, which includes 21 mostly cognitive-affective symptoms such as feelings like worthlessness, guilt, crying and self-dislike.