Depression, mood state, and back pain during microgravity simulated by bedrest

Objective: The objective of this study was to develop a ground-based model for spinal adaption to microgravity and to study the effects of spinal adap tation on depression, mood state, and pain intensity. Methods: We investiga ted back pain, mood state, and depression in six subjects, all of whom were exposed to microgravity, simulated by two forms of bed rest, for 3 days. O ne form consisted of bed rest with 6 degrees of head-down tilt and balanced traction, and the other consisted of horizontal bed rest. Subjects had a 2 -week period of recovery between the studies. The effects of bed rest on pa in intensity in the lower back, depression, and mood state were investigate d. Results: Subjects experienced significantly more intense lower back pain , lower hemisphere abdominal pain, headache, and log pain during head-down tilt bed rest. They had higher scores on the Beck Depression Inventory (ie, were more depressed) and significantly lower scores on the activity scale of the Bond-Lader questionnaire. Conclusions: Bed rest with 6 degrees of he ad-down tilt may be a better experimental model than horizontal bed rest fo r inducing the pain and psychosomatic reactions experienced in microgravity . Head-down tilt with balanced traction may be a useful method to induce lo w back pain, mood changes, and altered self-rated activity level in bed res t studies. Key words: depression, mood, lower back pain, lower abdominal pa in, leg pain, bed rest.