Normal Brain Activity Explains Behavior During Psychotic Episodes
The great variety of symptoms in schizophrenia has always made the prediction of a psychotic episode problematic. Scientists from the University of Cambridge have recently announced a method of anticipating the way people might behave during a psychotic episode. The answer lies in tracing the normal brain activity of the individual and then comparing the results of this with brain activity following the administration of Ketamine.
Paul Fletcher, MD, who led the study, used functional magnetic resonance imaging (fMRI), to measure brain activity in 15 healthy volunteers while they undertook a series of mental exercises. Following this, the behavior of volunteers was evaluated by use of several valid and reliable psychiatric scales.
The experiment required the volunteers to be involved in one of two experimental conditions. In the first condition volunteers were administered either a placebo or a measured dose of the drug ketamine. In the second condition, one month later, those who had been given placebo were given ketamine.
Ketamine, also known by its street name, "Special K," is known to induce both positive and negative symptoms of schizophrenia. The abuse of ketamine is thought to have started around the 1980s when it became used by some as part of the club scene. More recently ketamine has been used in controlled experimental conditions and is showing some promising results with conditions such as depression.
Researchers found that increased brain activity in the normal (placebo) condition predicted behaviors in the ketamine condition. Volunteers who showed more frontal and temporal lobe brain activity while imagining the sounds of voices, were more likely to experience strange perceptions in the ketamine condition. Similarly, volunteers who showed more brain activity when they were asked to complete simple sentences were more likely show disordered thinking in the ketamine condition.
The experiment has provided a biological link in our understanding of the processes of schizophrenia. The use of ketamine on healthy volunteers demonstrates how both disease and drug use produce such variable effects in people. Dr Fletcher has speculated that this could one day assist with early intervention strategies. In a prepared statement Dr Fletcher said, "our findings may provide a vulnerability marker to predict psychotic symptoms induced by drugs or disease. This perhaps raises the prospect of early intervention strategies targeted towards schizophrenia patients' individual patterns of symptom vulnerability."
The study is published in the June edition of The Journal of Neuroscience.