Neuropsychological impairment in fibromyalgia: relation to depression, fatigue, and pain.

OBJECTIVE: The present study assessed the relationship of depression, pain, and fatigue to subjective cognitive complaints and objective impairment in patients with fibromyalgia (FM), patients with other chronic pain disorders, and healthy controls.
METHOD: Neuropsychological assessment was conducted on 28 FM patients, 27 chronic pain patients, and 21 healthy controls. Five FM patients and five chronic pain patients were excluded due to poor effort on cognitive tasks. Assessment included measures of depression, pain, fatigue, subjective cognitive complaints, memory, executive functioning, intellect, attention, and psychomotor speed. Analysis of covariance was used to assess group differences in cognitive complaints and cognitive test performance, after controlling for depression, pain, and fatigue. Hierarchical regression was used to assess whether objective test performance was related to subjective cognitive complaints, after controlling for depression, pain, and fatigue.
RESULTS: FM patients had more memory complaints and reported more fatigue, pain, and depression than other groups. Groups were not different in cognitive performance, after controlling for fatigue, pain, and depression; depression was related to memory performance and fatigue was related to psychomotor speed. Neuropsychological test results did not add significantly to the variance accounted for in subjective cognitive complaints, after accounting for depression, pain, and fatigue.
CONCLUSION: Psychological factors, particularly effort, depression, and fatigue, are important in understanding both subjective cognitive complaints and objective cognitive impairment in FM and other chronic pain disorders.