ANXIETY DISORDERS AND BED REST

Among psychobiological concepts concerning origin and persistence of a nxiety disorders, the phenomenon of cardiovascular deconditioning (CD) has drawn little attention. Many of the cardiovascular complaints see n in patients with anxiety disorders can be evoked by CD. CD has been studied in astronauts during and after space flights, can be provoked on earth by using the 6 degrees head-down tilt (HDT) method, and occur s after prolonged bed rest. HDT studies conducted in our laboratory wi th healthy subjects revealed the detrimental cardiovascular effects of this posture. Based on this observation it was hypothesized that the CD seen in agoraphobics (with and without panic attacks) is mainly due to the long period of time they spent in supine position. 15 agorapho bics, 15 age-, sex- and body weight-matched snake-/spider-phobics and 15 healthy controls served as subjects. Orthostatic challenge, bicycle ergometry, and the behavior protocols filled in during 1 week showed that the agoraphobics are characterized by CD and spent significantly more time per day in supine position than spider-/snake-phobics and co ntrols. On the basis of these findings a psychophysiological model is proposed combining the prolonged bed rest with cardiovascular dysregul ation and the concomitant avoidance behavior.