Schizophrenia, bipolar disorder share gene variant: Study

Researchers have identified a genetic variant that is associated with multiple psychiatric disorders and drives changes in a brain network, thereby increasing an individual's risk of developing bipolar disorder and schizophrenia.

Schizophrenia is a primary psychotic disorder while bipolar disorder is a primary mood disorder but can also involve psychosis. However, differentiating between the two can sometimes be difficult because of some similar symptoms.

The findings, led by Stephane Jamain from the French National Institute of Health and Medical Research (INSERM), demonstrated that a variant of a gene -- SNAP25 -- involved in neurotransmission is associated with both disorders.

It also pointed out that patients with varying diagnoses in whom SNAP25 gene is implicated can give rise to a potentially new condition such as attention deficit/hyperactivity disorder.

In the study, published in the journal JNeurosci, the team used genetic analysis and neuroimaging in samples of adults with schizophrenia, early-onset bipolar disorder and healthy controls as well as postmortem analysis of brain tissue from schizophrenia patients.

The researchers found that this genetic variation changes the expression of the SNAP25 protein in the brain, which may impact information processing between brain regions involved in regulating emotions.

The variant was found to be associated with larger amygdala volume and altered prefrontal-limbic connectivity. Jamain and his team then replicated these findings in independent samples, minimising the potential for false positives and increasing confidence in their results. Their results confirmed a shared genetic component of these disorders.