The Involvement of the GH/IGF-I Axis in Cognitive Functions of AdultPatients and Healthy Subjects

摘要

The growth hormone/insulin-like growth factor I (GH/IGF-I) axis is an important regulator of brain functionwhich view is based on the evidence that 1) GH and IGF-I can cross the blood brain barrier, 2) GH and IGF-I can bind tosites in various brain structures, including the hippocampus, 3) GH can alter the dopamine turnover in the hippocampusand IGF-I the acetylcholine release, and 4) GH and IGF-I can activate the NMDA receptor in the hippocampus. Thesemechanisms may underlie the relationship between the GH/IGF-I axis and cognitive functioning. A reduced activity of theGH/IGF-I axis seems associated with cognitive dysfunction in adult patients with GH deficiency (GHD), Prader-Willisyndrome, traumatic brain injury (TBI), dementia and also with age-associated cognitive decline in healthy elderly.Moreover, IGF-I deficiency may be involved in the aetiology of schizophrenia. Treatment with GH appears to have abeneficial effect on cognitive functions in patients with GHD, Prader-Willi and TBI. However, as evidence of GHreplacement on cognition in distinct groups is limited and diet, exercise, and specific medicines have known effects on theGH/IGF-I axis, future studies on the relationship between GH-, diet-, exercise-, or medication-induced GH/IGF-I increaseand cognition are required.