In a study on 41 PD patients (11 men and 30 women), in which levels of proinflammatory cytokines and cortisol were measured in saliva, it was found that levels of IL-1β, IL-12 and tumor necrosis factor-α (TNF-α) were negatively correlated with cortisol levels [124]; the authors concluded that in PD patients the inflammatory response related to the altered microbiome-gut-brain axis is associated with HPA axis reactivity and may influence the maintenance of anxiety. Here, TNF is linked to Anxiety.