EFFECTS OF PHYSIOLOGICAL GROWTH-HORMONE (GH) THERAPY ON COGNITION ANDQUALITY-OF-LIFE IN PATIENTS WITH ADULT-ONSET GH DEFICIENCY

GH replacement of adults with acquired GH deficiency (GHD) results in body composition changes including increases in lean mass and bone min eral density. However, the effects of long-term GH therapy on cognitiv e function are largely unknown, and there are conflicting data regardi ng quality of life. We performed a randomized, double-blind, placebo-c ontrolled study of GH replacement in adults with GHD and measured cogn ition and sense of well-being using standardized psychometric tests be fore and after therapy. Forty men (median age 51 yr, range 24-64 yr) w ith a history of pituitary disease were randomized to GH therapy (star ting dose, 10 +/- 0.3 mu g/kg per day: mean treatment dose, 4 +/- 2 mu g/kg per day) vs. placebo for 18 months, and GH doses were adjusted a ccording to serum insulin growth factor-I levels. At baseline, the pat ients displayed a full-scale intelligence quotient (IQ) score nearly 1 SD above the normal mean. Mean scores on all cognitive tests fell wit hin normal limits, and on many tests, fell above the mean. On tests of verbal learning and delayed visual memory, mean test scores fell belo w the mean (although within normal limits), suggestive of a relative c ompromise in the area of memory performance. Following 18 months of GH replacement therapy, there were no significant changes in cognitive f unction or quality of life. We conclude that acquired GHD in adult men is not associated with significant alterations in cognitive function as assessed by standardized tests, and chronic low-dose GH replacement therapy does not result in significant beneficial effects on cognitiv e function or quality of life. Although previous studies have suggeste d that GH replacement in adults with acquired GHD may improve quality of life, our data do not support the use of physiological GH replaceme nt in GHD men for this indication.