When cortical development goes wrong: schizophrenia as a neurodevelopmental disease of microcircuits

Area of Science:

• Neuroscience
• Psychiatry
• Developmental Biology

Background:

• Schizophrenia is hypothesized to have a developmental origin.
• Previous research suggests abnormalities in neuronal structure and density in schizophrenia.

Purpose of the Study:

• To investigate neurodevelopmental defects in schizophrenia by examining dendritic spine loss, glutamatergic neuron density, and microgliosis.
• To correlate these neuropathological findings with the developmental hypothesis of schizophrenia.

Main Methods:

• Postmortem brain tissue analysis using Golgi staining to quantify dendritic spines on pyramidal neurons.
• Immunohistochemistry to assess the numerical density of glutamatergic neurons (using GluR 5/6/7 antibody) and glial cells (GFAP for astroglia, HLA-DR for microglia).
• Blind data collection and analysis to minimize bias.

Main Results:

• Significant reduction in dendritic spine density on cortical pyramidal neurons in schizophrenic brains compared to controls.
• Decreased numerical density of presumed glutamatergic neurons in the orbitofrontal cortex of schizophrenic patients.
• Markedly increased numerical density of microglia in the frontal and temporal cortex of schizophrenic individuals, without changes in astroglia.

Conclusions:

• The findings support a neurodevelopmental defect in schizophrenia affecting glutamatergic neurons and neuropil architecture.
• Increased microgliosis may reflect reactive changes in response to altered cortical neuropil.
• These neuropathological alterations may explain observed cortical volume loss without a decrease in overall neuronal density.