Higher doses of second-generation antipsychotics and more severe negative symptoms are associated with lower levels of oxytocin in cerebrospinal fluid among patients with schizophrenia, researchers report.
The findings, published in Schizophrenia Research, are "in line with the possibility that central oxytocin may ameliorate the severity of some symptoms of schizophrenia by improving social functioning," say Daimei Sasayama (National Center of Neurology and Psychiatry, Tokyo, Japan) and team.
The team studied 27 men with schizophrenia (mean age 42.6 years), 17 with major depressive disorder (mean age 39.5 years), and 21 mentally healthy controls (mean age 38.3 years).
Lumbar puncture was performed and levels of oxytocin in cerebrospinal fluid were measured using enzyme-linked immunosorbent assay.
Analysis revealed no significant differences among the groups regarding cerebrospinal fluid levels of the hormone.
However, transformed oxytocin levels in schizophrenic patients were significantly negatively correlated with second-generation antipsychotic dose and not with first-generation antipsychotics.
In addition, patients prescribed second-generation antipsychotics had significantly lower oxytocin levels than those who were not prescribed these drugs.
There was no significant difference in oxytocin levels between patients who were and were not prescribed first-generation antipsychotics.
The researchers also found that transformed oxytocin levels were significantly negatively correlated with the negative symptom subscale of the Positive and Negative Syndrome Scale (PANSS) in patients with schizophrenia. This correlation remained significant even after controlling for second-generation antipsychotic dose.
There were no significant associations between transformed oxytocin levels and other subscales of the PANSS.
There was also no correlation between oxytocin levels and age or body weight in any of the groups.
Previous studies have shown that oxytocin is released in response to a variety of stressful stimuli, explain Sasayama et al.
And the current study shows that "higher levels of cerebrospinal fluid oxytocin may be associated with less severe symptoms of schizophrenia," they conclude.
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