Cognitive functioning and cerebrospinal fluid concentrations of neuropeptides for patients with good neurological outcomes after aneurysmal subarachnoid hemorrhage.

Abstract

Many patients exhibit cognitive disturbances after aneurysmal subarachnoid hemorrhage (SAH). Structural and functional neuroimaging has failed to demonstrate any correlation with these complaints. This study was performed to investigate whether neuropeptide concentrations in cerebrospinal fluid could be related to cognitive disturbances after SAH. Lumbar cerebrospinal fluid was obtained, 3 to 6 months after surgery, from 17 patients who experienced good outcomes after aneurysmal SAH. The samples were analyzed for various neuropeptides using radioimmunoassays, and the peptide concentrations were evaluated in relation to scores on standardized neuropsychological tests. The neuropsychological test results were normal for eight individuals, whereas the remaining nine patients exhibited various degrees of cognitive impairment. There was no correlation between the concentrations of arginine vasopressin or neuropeptide Y and test performance. However, significant correlations between cognitive impairment and elevated levels of beta-endorphins (P = 0.02), corticotropin-releasing factor (P = 0.004), and delta sleep-inducing peptide (P = 0.045) were noted. Patients with cognitive impairments after aneurysmal SAH exhibited higher cerebrospinal fluid concentrations of endorphins, corticotropin-releasing factor, and delta sleep-inducing peptide than did those with normal capacity. This is probably attributable to diffuse derangement of transmitter release in the brain, resulting from the insult or ensuing complications, although a secondary increase in corticotropin-releasing factor concentrations caused by increased stress during the testing because of reduced cognitive capacity cannot be excluded.