Mitochondria are central to mental health, regulating energy, calcium, apoptosis, oxidative stress, neuroplasticity, and immune signaling, and their dysfunction is linked to major psychiatric disorders such as depression, bipolar disorder, and schizophrenia.

The mitochondrial hypothesis complements the neurotransmitter framework—dopamine and serotonin remain relevant, but energy deficits and intercellular mitochondrial signaling broaden our understanding of mental illness and its treatment.

Viewed as more than energy producers, mitochondria influence mood and cognition by orchestrating energy flow, calcium balance, and immune signaling within the brain.

Cell-free mitochondrial DNA is elevated in the cerebrospinal fluid and blood of individuals with depression, suggesting stressed neural tissue releases mitochondrial contents as distress signals.

Extracellular mitochondrial DNA is elevated in depression, indicating stressed neural tissue may release mitochondrial contents as distress signals, though the exact mechanism remains to be clarified.

Overall, extracellular mitochondrial DNA in CSF and blood points to a distress-signaling role of mitochondrial contents in depression.

Mitochondria can exist outside cells and travel between them, potentially acting as distant messengers and expanding brain-body communication beyond traditional neurotransmitters.

Extracellular mitochondria may circulate in blood and transfer between cells via astrocytes and platelets, signaling and potentially restoring function in damaged neurons.

This extracellular mitochondrial communication represents a novel pathway for brain-body signaling and intercellular coordination.

Mitochondria modulate neuroinflammation by influencing microglial activation and cytokine production, which can reduce neurogenesis and synaptic connectivity and may affect antidepressant efficacy.

Damaged mitochondria release DAMPs that trigger microglial cytokine responses, potentially lowering serotonin signaling and contributing to antidepressant resistance.

Mitochondrial-driven neuroinflammation can impair neurogenesis and synapse formation, linking energy dysfunction to mood disorder pathology and treatment challenges.