Recent studies indicated that increases in peripheral inflammation is a prodromal indicator of dementia, with greater cognitive impairment being associated with increased levels of IL-6 and TNF-α in Alzheimer’s and Parkinson’s disease [King et al., 2018; Wood, 2018; see Maletic and Raison (2014) for a review of how peripheral inflammatory signals can be transported into the brain in psychiatric disease]. This evidence concerns the gene TNF and psychiatric disorder.