title: Depression, mood state, and back pain during microgravity simulated by bed rest.
abstract: OBJECTIVE
  The objective of this study was to develop a ground-based model for spinal adaptation to microgravity and to study the effects of spinal adaptation on depression, mood state, and pain intensity.
  
  
  METHODS
  We investigated 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. One 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 pain intensity in the lower back, depression, and mood state were investigated.
  
  
  RESULTS
  Subjects experienced significantly more intense lower back pain, lower hemisphere abdominal pain, headache, and leg 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 head-down tilt may be a better experimental model than horizontal bed rest for inducing the pain and psychosomatic reactions experienced in microgravity. Head-down tilt with balanced traction may be a useful method to induce low back pain, mood changes, and altered self-rated activity level in bed rest studies.
authors.affiliation: Life Science Division, NASA Ames Research Center, Moffet Field, CA, USA. jorna.styf@orthop.gu.se
authors.forename: J R
authors.initials: JR
authors.lastname: Styf
authors.forename: K
authors.initials: K
authors.lastname: Hutchinson
authors.forename: S G
authors.initials: SG
authors.lastname: Carlsson
authors.forename: A R
authors.initials: AR
authors.lastname: Hargens
mesh_terms: D000328:Adult; D001416:Back Pain / Q000523:psychology*; D001510:Bed Rest; D003863:Depression / Q000523:psychology*; D018475:Head-Down Tilt; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000523:psychology*; D010147:Pain Measurement; D014893:Weightlessness