Subterranean biology researcher Masato Yoshizawa, an evolutionary biologist currently researching for the University of Hawaii, has been studying the Astyanax Mexicanus, the blind cave fish called the Mexican tetra, and recently presented evidence that some antipsychotic drugs cause behavior changes in the socially introverted fish.
His findings are encouraging for future psychiatric and schizophrenia research that may be able to be performed with the help of the Mexican tetra, which exhibits behaviors that mimic schizophrenia.
Schizophrenia in Humans
Schizophrenia affects the human ability to behave, think, and feel normally. Its symptoms both add to and disable regular thought patterns. The condition causes a reduction in emotional response and pleasure, muted facial expressions, a low inclination to speak, and an aversion to sustained activity. It can also overload the thought process with hallucinations, delusions, dysfunctional thought patterns, and agitated bodily movements. These symptoms are accompanied by impaired decision-making and focus. The traits of humans affected by schizophrenia are often described as hyperactive and asocial.
Schizophrenia in Mexican Tetra Cave Fish
The blind cave fish Mexican tetra exhibits similar characteristics to humans with schizophrenia. The species as a whole is solitary due to a lack of natural predators. They have no need to join protective schools and are instead able to independently navigate underwater using variations in water pressure and vibrations. Despite their safety in the dark recesses, they remain anxious and restless. The fish repeat behaviors incessantly without sleeping.
The fish show the closest behaviors of any animal researched so far to human schizophrenia. In fact, the fish seem to have about 90 percent of the genes with known risk factors for psychiatric disease.
Administration of Antipsychotics to Cave Fish
Clozapine Pill
Yoshizawa has attempted to quell the natural erratic behaviors of the cave fish with fluoxetine, commonly branded as Prozac, and clozapine. According to Yoshizawa (courtesy of Science):
"Overall, these drug responses in cave fish are very similar to what you see in human patients… These are strong evidence that cave fish could be a good model for human psychiatric disease."
Before broad conclusions can be drawn, Yoshizawa's research team must perform larger-scale tests on populations of the Mexican tetra to determine how the efficacy of the drugs is affected across multiple genetic makeups. Recording and studying changes in behavior may help to narrow the range of possible risk factor genes enough to create more targeted treatments for schizophrenia. There is one major roadblock: fish are not humans, and humans are not fish. Research will have to be carefully performed and conclusions must be rigorously tested if new medical treatments are to come of these discoveries.
