“Elevated pro-inflammatory cytokines and increased macrophage densities have been found in ∼ 35–50 % of schizophrenia and bipolar disorder brains.”

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“…..the influence of neuroinflammation on the blood–brain barrier in these serious mental illnesses remains unclear.”

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“Here, we measured and compared multiple blood–brain barrier-associated molecules in the ventral midbrain, including chemokines, macrophage markers, adhesion molecules, tight junction proteins, and basement membrane proteins in people with schizophrenia, or bipolar disorder, and controls….stratified by inflammatory status.”

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“Both mRNA and protein levels of macrophage chemokine and macrophage scavenger receptor were significantly elevated in the neuroinflammatory schizophrenia (high) compared to all the low inflammatory subgroups.”

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Collectively, the high inflammatory individuals in both schizophrenia and/or bipolar disorder display more signs of blood–brain barrier alterations, including increased macrophage chemoattraction, changed adhesion molecules, and altered tight junction proteins, though they have distinct molecular signatures of blood–brain barrier pathology in the midbrain.”

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Y.Zhu, et al

Discovery of novel blood–brain barrier neuropathology in schizophrenia and bipolar disorder midbrain

Brain, Behvior, and Immunity — Volume 134 — May 2026