Pain state as artifact in the psychological assessment of recurrent headache sufferers.

The finding that recurrent headache sufferers, particularly tension headache sufferers, obtain higher scores on psychological symptoms measures than controls was replicated in 262 recurrent (tension, mixed, and migraine) headache sufferers and 26 controls. However, closer examination of the data revealed that psychological symptoms were elevated only in patients who experienced head pain at the time of assessment. This finding raises the possibility that previously reported elevations in psychological symptoms have resulted from uncontrolled differences in the pain state of respondents. Retrospective reports of headache activity also were related to pain state. In contrast, a measure of perceived control of factors affecting headaches was unrelated to pain state. As a result, locus of control (but not psychological symptoms) successfully differentiated recurrent headache sufferers from controls even when headache sufferers were tested when pain free. These results suggest that psychological symptom measures may yield misleading results when used with individuals with pain disorders.