Schizophrenia May Cause Widespread Synapse Loss in Brain, US Study Finds Potential Starting Point

Schizophrenia may leave a distinct biological mark on the brain's neural communication network, according to a new US study published in Molecular Psychiatry. The research offers a potential "starting point" for understanding the disease's progression.

Synapses, the crucial contact points between neurons that enable information exchange, are vital for memory, attention, emotion, and decision-making – functions often impaired in schizophrenia. Scientists have long suspected that abnormal synapse development or loss plays a role in the disorder.

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Synapses are the tiny contact points between neurons that allow neurons to exchange information with each other.

While standard MRI scans can detect structural brain changes, they cannot directly quantify synapse numbers. A research team from Rutgers University utilized Positron Emission Tomography (PET) scans to map areas with the most significant reduction in synaptic connections among schizophrenia patients. The study examined the synaptic density in 122 participants, including 29 diagnosed with schizophrenia.

The scans revealed widespread synaptic connection loss in the brains of schizophrenia participants, with the most pronounced differences observed in the frontal and temporal lobes, as well as brain regions involved in memory and emotion processing. The researchers then used computer models to simulate how this synaptic loss might spread through the brain's structural connections. Their simulations indicated that a specific region in the left frontal lobe could be the origin of these changes, with abnormalities potentially extending over time to interconnected areas.

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The research team's next step is to identify the 'starting point' from which synaptic loss begins to spread.

This asymmetry is particularly noteworthy, as the left side of the brain houses neural networks crucial for language, planning, and other functions frequently affected by schizophrenia. The study found that synaptic loss was significantly greater in the left hemisphere compared to the right. These reduced synaptic areas are rich in receptors for serotonin, GABA, and glutamate, neurotransmitters critical for regulating mood, perception, and learning.

The researchers stated that their findings suggest synaptic loss in schizophrenia is not random but appears to follow the brain's structural and neural connectivity. This discovery could guide scientists in identifying and targeting specific brain regions for intervention and treatment. However, the study, observing participants at a single time point, cannot definitively determine when synaptic changes begin or if they worsen as the disease progresses. Long-term follow-up studies are needed to understand how disease duration, treatment, and other factors influence synaptic loss.

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The study shows that synaptic loss in schizophrenia is not random; it appears to follow the brain's structural and neural connections.