Background. The aim of the study was to search for the
existence of, and define, a possible
relationship between performance in neuropsychological tests and baseline
concentrations of
plasma cortisol, vasopressin and oxytocin in medication-free patients with
a major depressive
episode.
Methods. Measures of depression and anxiety were obtained and
a
neuropsychological battery was
presented. Blood for neuropeptide analysis was drawn by venepuncture at
8.00, 16.00 and 23.00 h.
Results. The melancholic patients performed less well on
the neuropsychological battery than did
the non-melancholic patients, but these differences could be accounted
for by the severity of the
illness. Global intellectual functioning was negatively correlated with
mean baseline plasma
concentrations of cortisol. Patients with high mean plasma vasopressin
concentrations remembered more auditory presented words in the delayed
recall test and produced more intrusions in the visual
word learning list than did patients with low or normal mean plasma vasopressin
concentrations.
No association was found between neuropsychological performance and plasma
concentrations
of oxytocin.
Conclusions. Our findings support the hypothesis that elevated
baseline plasma cortisol
concentrations are related to cognitive impairment in depressed patients
and the hypothesis that the
neuropeptide vasopressin independently enhances memory, directly or
indirectly through increasing arousal and attention.