ME/CFS, depression, and poorly evidenced theories
It occured to me recently that there are quite a number of similarities between the chemical imbalance theory of depression and the traditional (bio)psychosocial view of ME/CFS, with regard to how these ‘models’ came to dominate our understanding of both illnesses and how they should be treated. This is certainly not a groundbreaking observation, but it is probably useful to set out the similarities, while noting that whereas the chemical imbalance theory gave a physiological footing to depression, the (bio)psychosocial model of ME/CFS is based on the view that the illness is not driven by any biological abnormalities indicitive of disease.
| Depression | ME/CFS | |
|---|---|---|
| Historical understanding | Caused by stressful events, unhappiness, loneliness | Prolonged or absent recovery after infection (usually viral) |
| Theory | Chemical (serotonin) imbalance in the brain | Illness perpetuated by psychosocial factors: fear avoidance and deconditioning |
| Evidence supporting theory | Indirect and inconsistent measurements; responses to similar medications | Apparent patient behaviour; lack of biomarker |
| Suggested treatments | SSRI/SNRI medications | Graded exercise therapy (GET) and/or cognitive behavioural therapy (CBT) |
| Treatment harms | Drug side effects, dependency & withdrawal effects | Worsening of symptoms; increased disability |
| Present understanding | Unknown & disputed: Numerous mechanisms — e.g., brain network dysfunction; inflammation — probably also involved | Unknown: Numerous mechanisms — e.g., immune and neurological dysfunction; metabolic disturbances — likely implicated |