The effect of growth hormone on neuropsychological outcomes and quality of life of patients with traumatic brain injury: a systematic review.

Abstract

One of the most devastating chronic consequences of traumatic brain injury (TBI) is cognitive impairment. One of the possible underlying causes is growth hormone deficiency (GHD) due to TBI-induced hypopituitarism. Currently, TBI patients are not routinely screened for pituitary function, and there are no standard therapies when growth hormone (GH) deficiency is diagnosed. Furthermore, the possible positive effects of GH replacement on cognitive function and quality of life after TBI is not well established. We aimed to assess the current knowledge on the effect of GH therapy on cognitive function and quality of life after TBI. We performed a literature search in PubMed, EMBASE, and CENTRAL databases from inception to October 2019. We extracted data on each term of severity (mild-moderate-severe) of TBI with and without GHD, time since injury, parameters of growth hormone treatment (dosing, length) and cognitive outcomes in terms of verbal and non-verbal memory, executive, emotional and motor functions and performed a meta-analysis on results of digit span test assessing working memory. We identified 12 studies (containing 2 randomized controlled trials) with n=264 mild-to-moderate-to-severe TBI patients (GCS varied between 6 and 15) with (n=255) or without GHD (n=9) who received GH therapy. GH was administered subcutaneously in gradually increasing doses, monitoring serum insulin-like growth factor-I (IGF-I) level. After TBI regardless of GCS 6-12 months GH therapy, started in the chronic phase post-TBI, induced a moderate improvement in processing speed and memory capacities, decreased the severity of depression and led to a marked increase in quality of life. Limitations include relatively low number of patients involved and divergent neuropsychological tests used. These results urge further multicentric controlled studies to substantiate the use of GH replacement therapy as a potential tool to alleviate TBI-related cognitive impairment and improve quality of life.