Allergy and depression: A neurochemical threshold model of the relation between the illnesses.

Empirical studies suggest a very high prevalence of atopic disorder in people with depression. Research indicates that individuals with allergy have cholinergic hyperresponsiveness and beta-adrenergic hyporesponsiveness in the autonomic nervous system. Evidence is reviewed that similar imbalances in central nervous system cholinergic-adrenergic activity play a casual role in depression behaviors. It is hypothesized that the allergic state or allergic reactions can accentuate cholinergic-adrenergic activity imbalances in the central nervous system of a small subgroup of people at risk for endogenous depression thereby producing depression symptomatology.