Mechanisms explaining the association between low back trouble and deficits in information processing - A controlled study with follow-up

Study Design. A controlled study with a 6-month follow-up period. Objectives. To find an explanation for the association between impairment i n information processing, i.e., slow reaction times, and chronic low back t rouble. Summary of Background Data. Low back trouble, chronic pain in general, and depression have been associated with impaired cognitive functions and slow reaction times, It is a common phenomenon that the preferred hand performs better than the nonpreferred hand in motor tasks. The authors hypothesized that chronic low back trouble hampers the functioning of short-term memory in a way that leads the preferred hand to loose its advantage over the nonp referred hand, but that the advantage would be restored during the rehabili tation. Methods, Sixty-one healthy control subjects and 68 patients with low back t rouble participated in the study. Reaction times for the preferred and nonp referred upper limbs were tested. A multiway analysis of covariance was use d to examine the group, handedness, and rehabilitation effects on reaction times. The hypothesis was specifically tested with a third-degree interacti on: group-handedness-rehabilitation. Results. A significant interaction among group, hand edness, and rehabilita tion was found (P = 0.05). At the beginning, the reaction times for the pre ferred hand were faster among the control subjects (P = 0.001), but not amo ng the patients with low back trouble (P = 0.62). After the rehabilitation, the preferred hand was faster both among the control subjects (P = 0.001) and the patients with low back trouble (P = 0.0002). During the rehabilitat ion, back pain, psychological distress, and general disability decreased si gnificantly among the patients with chronic low back trouble. Conclusions. The results support the hypothesis that chronic low back troub le (i.e., pain, psychological distress, and general disability) hampers the functioning of short-term memory, which results in decreased speed of info rmation processing among patients with chronic low back trouble.