drug therapy for schizophrenia

A deficiency in the brains of people with schizophrenia that could lead to the development of new drug therapies has been discovered by researchers at the RIKEN Center for Brain Science (CBS) in Japan. The results were published in Schizophrenia Bulletin.

In recent years, drug therapy for schizophrenia has come to a stand-still. Most of the drugs available for schizophrenia are based on dopamine, but they are ineffective in about one out of every three patients. “because we don’t have another angle on what causes schizophrenia. Many pharmaceutical companies are pulling out of schizophrenia-related drug development” says Takeo Yoshikawa, team leader at KIREN CBS. “ hopefully, our findings can provide the new angle with a new target for drug development.”

Although, schizophrenia is a well-known mental disorder that affects the brain, how it does so remains somewhat of a mystery. Scientists have known for some time that the brains of people with schizophrenia have less white matter than normal brains. White matter in the brain is made from oligodendrocytes special cells that wrap around the parts of neurons that carry outgoing signals, which help them communicate with each other. Characteristic symptoms of schizophrenia include hallucinations and the inability to distinguish reality from fantasy, which might originate in white matter abnormalities that cause irregular communication between neurons.

Led by Takeo Yoshikawa, the team at RIKEN CBS investigated sphingolipids, a group of lipids known to have many functions, some related to white matter. Postmortem analysis of the large white matter tract that connects the left and right sides of the brain showed a severe deficiency in S₁P, a sphingolipid necessary for oligodendrocyte production. Further tests showed that although normal amounts of S₁P had been produced, it was metabolized and degraded when it should not have been. “drugs that prevent S₁P degradation could be particularly effective in treating schizophrenia” says the first author and postdoctoral research scientist, Kayoko Esaki.

Although the experiment sounds simple, measuring S₁P levels in postmortem brains was a big challenge and required interdisciplinary expertise in chemistry--specifically, mass spectrometry—that was brought to the team by Esaki.” this was the first psychiatric study of the postmortem brain to use mass spectroscopic analysis, and our discovery would not have been possible without our newly established comprehensive technique for screening sphingolipids.” Says Yoshikawa.

After findings S₁P sphingolipid deficiency in schizophrenia, the researcher examined the postmortem brains of people with bipolar disorder or major depressive disorder. They found that S₁P levels did not differ from what they found in normal brains, indicating that the problem is specific for schizophrenia and not a common feature of mental disorders.

Before schizophrenia specific clinical trials can begin, studies in animals will be necessary. “ the next important step.” Says Yoshikawa, “is to determine precisely which S₁P receptor-acting drugs are effective in experimental animals. Although the new blockbuster drug fingolimod works at the S₁P receptor and is effective at treating multiple sclerosis, we do not yet know effective it would be for schizophrenia.”