Two grams of sarcosine in schizophrenia – is it too much? A potential role of glutamate-serotonin interaction
The patient was a 23-year-old male suffering from schizophrenia for 5 years (diagnosed according to the International Classification of Diseases-Tenth Revision), who had undergone psychiatric hospitalization four times in the past, most recently 3 years earlier. The first episode involved a picture of typical paranoid syndrome and was induced by amphetamines. Subsequent psychotic episodes were not related to drug use. During a stable period, the patient presented mild severity of negative (blunted and inappropriate affect, social withdrawal) and depressive symptoms and moderate cognitive problems (memory and attention), which were the main indication for administration of sarcosine. Among positive symptomatology, the patient described only periodic mild racing thoughts without typical delusions or hallucinations. Both parents were diagnosed with schizophrenia. After receiving information about sarcosine, the patient signed an informed consent form and started receiving the amino acid. Basic laboratory tests were performed (complete blood count, electrolytes, liver and renal parameters, lipids, prolactin, and thyroid stimulating hormone), which showed no deviations from reference values. The patient had no neurological, endocrine, or other chronic comorbidities at the time of treatment. We excluded ongoing alcohol and drug dependence or use in the previous 6 months (using a panel drug testing), but the patient smoked about 15 cigarettes per day. He was unemployed at that time and on a disability living allowance. Before addition of sarcosine, the patient has been receiving quetiapine 500 mg per day for 2 years and citalopram 10 mg per day for several months. Citalopram was prescribed due to panic attacks and negative symptoms.\nDuring the first 2 weeks of sarcosine administration at 2 g per day, the patient reported improvement in overall activity, concentration, and mood. After a further 2 weeks, he reported moderate inner tension with mildly increased drive, excessive activity and irritability, and a significant increase in sexual tension. Further examination ruled out a diagnosis of hypomania. The patient found these symptoms to be very unpleasant and asked for modification of his treatment. The overall impact of sarcosine he described as positive, and therefore it was decided to maintain the sarcosine supplementation but to reduce the dose by half to 1 g per day. After lowering the dose of sarcosine without changes in the dosage of his concomitant medications, the intensity of his excitation and irritability decreased, and the patient subjectively described his overall mental state as better in comparison with the period before sarcosine and treatment with 2 g of the amino acid (see ). There were no external circumstances to explain the observed intensity of psychomotor agitation symptoms.