Depression and pain in patients with Fibromyalgia Syndrome and neuropathic pain

A team of researchers at the Department of Neurology at the Danish Pain Research Centre carried out a staudy to examine whether the mechanisms associated with mental distress are different between Fibromyalgia Syndrome patients and other chronic pain patients.

Chronic pain is often associated with comorbidities such as anxiety and depression, resulting in a low health-related quality of life. The mechanisms underlying this association are not clear, but a disturbance in the pain control systems from the brain stem has been suggested and this was the hypothesis explored by this study.

Thirty neuropathic pain patients, 28 Fibromyalgia Syndrome patients and 26 pain-free age- and gender-matched controls were included and examined with respect to mental distress (self-rated Symptom Checklist-92), depression (doctor-rated Hamilton Depression Scale and self-rated Major Depression Inventory), and anxiety (doctor-rated Hamilton Anxiety Scale and self-rated Anxiety Inventory).

In addition, patients assessed their health-related quality of life (SF-36).

The researchers found that chronic pain patients with both Fibromyalgia Syndrome and Neuropathic Pain had significantly more mental distress, including depression and anxiety, than healthy controls, both by self-rating and by a professional rating.

However, these scores are low compared to other studies on mental distress in chronic pain patients.

Only a few chronic pain patients in this study met the diagnostic criteria for depression: 3.3% of the Neuropathic Pain patients (1 patient) and 7.1% of the Fibromyalgia Syndrome patients (2 patients).

Associations between pain and mental symptoms were only found in the Fibromyalgia Syndrome group despite similar pain intensities.

The researchers concluded that: "The findings suggest that different mechanisms are responsible for the development of mood disorders in the two patient groups."

However, the small sample sizes used in this study and the very small number of particpants who met the criteria for depression, mean that the study provided little significant data.

References:

1. Gormsen L, Rosenberg R, Bach FW, Jensen TS. Depression, anxiety, health-related quality of life and pain in patients with chronic fibromyalgia and neuropathic pain. Eur J Pain. 2009 May 25. [Epub ahead of print]