Plasma D-serine levels reduced in schizophrenia

By Mark Cowen, Senior medwireNews Reporter

Patients with schizophrenia exhibit significantly lower plasma levels of the amino acid D-serine than mentally healthy individuals, Brazilian researchers report.

Rogerio Panizzutti (Universidade Federal do Rio de Janeiro) and team also found that plasma D-serine levels negatively correlated with negative symptom severity in patients with the mental health disorder.

As D-serine is the major endogenous co-agonist of N-methyl-D-aspartate (NMDA) glutamate receptors in the brain, the findings support the hypothesis that hypofunction of NMDA receptors is associated with schizophrenia, say the researchers.

The findings come from a study of 84 patients with schizophrenia, aged a mean of 41.7 years, and 75 gender- and age-matched controls.

Blood samples collected from all of the participants and assessed for D-serine levels using high-performance liquid chromatography.

The researchers found that mean plasma levels of D-serine were significantly lower in schizophrenia patients than controls, at 4.27 versus 6.88 µmol/L.

The ratio of D-serine to total serine was also significantly lower in schizophrenia patients than controls, at 0.028 versus 0.036.

In the schizophrenia group, D-serine levels inversely correlated with total Brief Psychiatric Rating Scale (BPRS) scores and BPRS negative symptom scores. However, there was no correlation with BPRS positive symptom scores.

Panizzutti and colleagues conclude in Schizophrenia Research: "The finding of decreased plasma levels of D-serine in schizophrenia supports the hypothesis that lower levels of this amino acid may contribute to the biochemical basis of this disorder and highlight the need for further investigation of the role of D-serine in the symptomatology of schizophrenia."

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