Psychotic symptoms such as hallucinations, delusions, personality changes, and disorganized thinking occur in several psychiatric disorders, including schizophrenia, bipolar disorder, and psychotic depression. Scientists understand little of what goes wrong in a psychotic person's brain, but hope that brain imaging and systematic characterization of genetic activity and protein composition in the brain might help to shed light on mental diseases, eventually leading to better diagnosis, treatment, and possibly even prevention. A new study by Sabine Bahn and colleagues (Cambridge University) published in the international open-access journal PLoS Medicine provides a step in that direction.
The researchers compared the protein composition in the cerebrospinal fluid (the clear body fluid that surrounds the brain and the spinal cord) of 79 patients with different psychotic disorders and 90 mentally healthy individuals who served as controls. They found that samples from patients with psychosis had a number of characteristic changes compared with samples from control individuals, and that those changes were not found in the patients with other mental illnesses. They then wanted to test whether they would see the same pattern in a separate set of patients with psychotic illness, which turned out to be the case. Two of the changes in the cerebrospinal fluid associated with schizophrenia, namely higher levels of parts of a protein called VGF and lower levels of a protein called transthyretin, were also found in post-mortem brain samples of patients with schizophrenia compared with samples from controls.
These results suggest that this approach has the potential to find biomarkers for psychosis and possibly schizophrenia, which would be helpful for diagnosis and might help to understand the molecular basis for these conditions. If shown, in future studies, to be directly involved in causing the disease symptoms, they would be important targets for rational treatment and prevention efforts.
Citation: Huang JTJ, Leweke M, Oxley D, Wang L, Harris N, et al. (2006) Disease biomarkers in cerebrospinal fluid of patients with first-onset psychosis. PLoS Med 3(11): e428. (http://dx.doi.org/10.1371/journal.pmed.0030428)
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