Context: Impaired cognitive performance has been demonstrated in adults with GH deficiency and acromegaly by using different neuropsychological tests. P300 event related potential (ERP) application is a well established neurophysiological approach in the assessment of cognitive performance.
Objectives: Evaluation of cognitive performance by using P300 ERPs has not been reported in acromegaly, and the comparisons of the P300 ERPs between the patients with GH deficiency and GH excess have not been done yet. Therefore present study was designed to investigate the effects of GH deficiency and GH excess on cognitive performance by using P300 ERPs.
Design and methods: The study comprised 19 patients with severe GH deficiency, 18 acromegalic patients and 16 age, education and sex matched healthy controls. Baseline auditory ERPs were obtained at Fz (frontal), Cz (central), Pz (parietal) and Oz (occipital) electrode sites in GH deficient group, GH excess group and control group.
Results: There was a significant difference between mean serum IGF-I levels in the GH deficient and acromegalic patients (48+/-38 ng/ml and 742+/-272 ng/ml, respectively) (P=0.01). The mean P300 latency of the patients with GH deficiency was significantly (P=0.0001) prolonged when compared with that of normal controls and acromegalic patients at all electrode sites. The mean P300 amplitude of the patients with acromegaly was significantly (P=0.005) lower when compared with that of normal controls and GH deficient patients at all electrode sites.
Conclusions: Using ERPs recordings, the present study indicates the prolongation of P300 latencies in patients with severe GH deficiency and reduction of P300 amplitudes in patients with acromegaly. This study provides the electrophysiological evidence for the presence of cognitive dysfunction in both GH deficiency and GH excess, and different components of the cognitive performance are impaired in these conditions.