The contribution of mTOR to the immunopathology of bipolar disorder

The mammalian target of rapamycin (mTOR) has a role in immune regulation and neuroplasticity within the brain, influencing various neurological and psychiatric disorders, including bipolar disorder. mTOR signaling, via two complexes, mTORC1 and mTORC2, modulates immune responses by regulating microglial activation, cytokine production, and T-cell function. Dysregulation of these pathways leads to neuroinflammation, a hallmark of several neurological conditions. In bipolar disorder, mTOR affects neuroplasticity by modulating brain-derived neurotrophic factor (BDNF) levels and synaptic remodeling, essential for mood stabilization. Reduced mTOR signaling during depressive episodes and increased activity during manic phases have been observed, with potential links to the cognitive and emotional deficits characteristic of bipolar disorder. This review aims to compile the contribution of mTOR signaling to the immunopathology of bipolar disorder, focusing on its role in immune modulation, neuroinflammation, and neuroplasticity.