Physical activity and plasma cyclic adenosine monophosphate levels in manic-depressive patients and healthy adults.

Intense exercise for one hour induced a significant increase in plasma cyclic adenosine monophosphate (cAMP) in 5 healthy volunteers. In 44 manic-depressive patients, cAMP levels correlated more strongly with mood ratings than with activity scores. The authors conclude that physical activity is one of the factors which contribute to changes of cAMP levels in affective illness.