While a robust body of research demonstrates that inflammation and elevated cytokines are closely associated with major depressive disorder and play a key role in a subset of patients, framing depression as 'fundamentally an inflammatory disease' is contested because depression is widely understood as a multifactorial condition involving neurotransmitter, endocrine, and neuroplasticity mechanisms alongside immune dysregulation.
The retrieved literature consistently shows a strong correlation and mechanistic link between inflammation and major depressive disorder (supporting indices 2, 4, 5, 8, 10, 11). However, comprehensive reviews on MDD pathogenesis emphasize that inflammation is one of several overlapping hypotheses (such as the monoamine, HPA axis, and neuroplasticity theories) and only affects a subset of patients (around 27% according to paper 8), meaning it is not universally considered the fundamental sole cause of all depression (supporting indices 6 and 8). Therefore, the verdict is CONTESTED rather than fully SUPPORTED.