Approximately 1% of the world’s population have schizophrenia, with 3.2 million Americans having the disorder. Now, for the first time, advanced brain scanning techniques have allowed researchers to observe that people living with schizophrenia have lower levels of a protein found in the connections between neurons.
Scientists were first to hypothesise that schizophrenia is caused by dysfunctional synapses in the early 1980’s. Until now, however, they were only able to study this indirectly, by examining post-mortem brain samples, or animal or cell models in the lab.
Thanks to new brain imaging techniques however, this is no longer the case. In their study, a team of researchers from the UK recruited 18 adults with schizophrenia, and 18 without the condition. They then injected a tracer detectable by positron emission tomography (PET) brain scans in each of their brains. The tracer used is known to bind to a protein located in synapses and synaptic vesicle glycoprotein 2A (SV2A), a good marker of the density of synaptic nerve endings in the brain.
In the end, they found that people with schizophrenia tend to have lower levels of protein SV2A in the front parts of their brains, regions involved in planning. Professor Oliver Howes, leader of the study, said, “Our current treatments for schizophrenia only target one aspect of the disease—the psychotic symptoms—but the debilitating cognitive symptoms, such as loss of abilities to plan and remember, often cause much more long-term disability and there's no treatment for them at the moment. Synaptic loss is thought to underlie these symptoms.”
Throughout the experiment, the researchers gave the patients with schizophrenia antipsychotic medication. However, to be sure that this could not be responsible for their reduced quantities of protein SV2A, they conducted a rat experiment too- feeding rats antipsychotic drugs haloperidol and olanzapine for 28 days. As the drugs had no effect on their levels of protein SV2A, the researchers concluded that their findings are more likely a direct result of schizophrenia instead.
Howes said, "Next we hope to scan younger people in the very early stages to see how synaptic levels change during the development of the illness and whether these changes are established early on or develop over time."