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Eyeless Albino Cave Fish Help Explain Schizophrenia and Autism

According to new research, anxious cave fish may serve as model organisms for understanding human psychiatry.
Image: NIH

The Mexican tetra or blind cave fish (Astyanax mexicanus) is a solitary species. With no natural predators, it does not join protective schools, instead peacefully inhabiting dark underwater recesses and navigating by way of variations in water pressure or underwater vibrations. But despite a relatively safe existence, the blind cave fish is known to be restless and anxious. They do not sleep and can often be found repeating the same behaviors over and over again. Asocial and hyperactive, Mexican cave fish seem to display symptoms of human psychiatric conditions.

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Last week at the 23rd International Conference on Subterranean Biology, Masato Yoshizawa, an evolutionary biologist at the University of Hawaii, presented new research demonstrating the effects of certain drugs known to help people with schizophrenia and autism on blind cave fish. What Culver found is a remarkable similarity in behavioral changes in cave fish and in human patients, which may point the way toward future uses of the fish as model organisms in psychiatric research.

This is something we don't really have currently. Studying the genetic basis of psychiatric conditions in mice, the standard model organism, leads to often unsatisfactory results because mice often don't display the expected psychiatric behaviors despite being preloaded with the right genes. It so happens that cave fish already feature some 90 percent of the classic risk factor genes for human psychiatric disease.

Yoshizawa treated cave fish with two medications: fluoxetine (Prozac) and clozapine (an antipsychotic used to treat schizophrenia). What he found was a marked decrease in "symptoms" among the treated fish. "Overall, these drug responses in cave fish are very similar to what you see in human patients," he told the conference, according to Science. "These are strong evidence that cave fish could be a good model for human psychiatric disease."

Yoshizawa and his fellow researchers are now studying the behaviors of large numbers of cave fish in the hope of correlating behavioral extremes with genetic variations. The next step will be to explore how these genetic variations may interact with the cave fish environment to produce such human-like symptoms. Eventually, the goal is to identify a subset of genes implicated in schizophrenia and autism. The list of currently suspected genes is still quite long.