HOUSTON – Growth hormone deficiency appears to be common among military veterans with mild traumatic brain injury sustained in combat, according to the first study to look at the issue.
Future studies will attempt to confirm the new finding that GH deficiency in the setting of traumatic brain injury (TBI) appears to be associated with specific neuropsychologic abnormalities, and, further, whether GH replacement therapy in affected veterans enhances TBI rehabilitation efforts, according to Dr. Adriana G. Ioachimescu of Emory University, Atlanta.
At the annual meeting of the Endocrine Society, she presented the results of a pilot study of 20 men (mean age, 34 years) with mild TBI resulting from military combat. The last injury occurred an average of 44 months earlier.
Five subjects, or 25%, were GH deficient on the basis of a peak value of less than 3 ng/mL in response to a glucagon stimulation test. One GH-deficient veteran also had an abnormally low insulin-like growth factor-1 level. But all subjects had normal thyroid status and cortisol function.
Four GH-deficient men and 12 GH-sufficient men were able to put enough effort into their neuropsychologic testing for the results to be valid. The two groups performed similarly on measures of memory, learning, and simple and complex attention.
In contrast, GH deficiency appeared to be associated with executive dysfunction, as manifest in worse performance on measures of inhibitory control and self-monitoring. Depression also was more severe in the GH-deficient men, although they did not experience greater levels of fatigue or posttraumatic stress disorder. The GH-deficient group also scored significantly lower on a validated quality-of-life measure.
This study was supported by Novo Nordisk. The presenter reported having no financial conflicts.