Objective: Impaired cognitive function has been demonstrated in adults with GH deficiency (GHD) and acromegaly by using different neuropsychological tests. P300 ERP application is a well established neurophysiological approach in the assessment of cognitive function. However the comparison of the P300 ERPs between GHD and GH excess have not been done yet. The present study was designed to investigate the effects of GHD and acromegaly on cognitive function by using P300 ERPs.
Methods: The study comprised 17 patients with severe GHD (6 male, 11 female), with a mean age of 47.5±9.8 yr, 16 acromegalic patients (6 male, 10 female), with a mean age of 40.3±11.2 yr, and 15 age, education and sex matched healthy controls. ERPs were recorded at the Fz (frontal), Cz (central), Pz (parietal) and Oz (occipital) electrode sites; and P300 latencies and P300 amplitudes were estimated at all electrode sites. Standard Oddball paradigm was used to evoke P300 responses.
Results: There was a significant difference between the mean serum IGF-I concentrations in the GHD patients and acromegalic patients (51±13 ng/ml and 762±300 ng/ml). The mean P300 latencies (at all electrode sites) of the patients with GHD were significantly prolonged when compared with those of normal controls and acromegalic patients (P<0.05). The mean P300 amplitudes (at all electrode sites) of the patients with acromegaly were significantly decreased when compared with those of normal controls and GHD patients (P<0.05).
Conclusions: P300 latency is related to stimulus evaluation time, and P300 amplitude is related to decision making and memory processing. The present study therefore clearly demonstrates that different components of cognitive function are impaired in GHD and GH excess. This is an objective electrophysiological evidence for cognitive dysfunction in GHD and acromegaly.