Schizophrenic patients demonstrate a variety of cognitive deficits, including attention, executive functions, and working memory, even in the early stage of disease. In the present study, we examined the association between blood levels of 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), or brain-derived neurotrophic factor (BDNF) and scores on the Wisconsin Card Sorting Test (WCST) in patients with early-stage schizophrenia. We also investigated the association between frontal GABA levels using 1H-magnetic resonance spectroscopy (MRS) at 3T and scores on the WCST in the same patients. Blood levels of BDNF and catecholamine metabolites and brain GABA levels using 1H-MRS were measured in 18 schizophrenic patients (nine males, nine females; age range 13-52 year). A significantly positive correlation was observed between plasma MHPG levels and %PEM (rho = -0.686, p = 0.0047). A trend toward negative correlation was found between frontal lobe GABA levels and the per cent of preservation error (%PEM) in the early stage of schizophrenia (rho = -0.420, p = 0.0836). These results suggest that noradrenergic neurons might be involved in neuropsychological functions in early-stage of schizophrenia.
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