Serum concentrations of interleukin 18 and 25-hydroxyvitamin D-3 correlate with depression severity in men with psoriasis

Objective Psoriasis and depression may have common mechanisms, such as systemic inflammation, dysfunction of the hypothalamic-pituitary-adrenal axis, and vitamin D-3 deficiency. Among men with psoriasis, this study examined whether depression severity was associated with serum concentrations of different metabolic and inflammatory markers. Methods The study included 85 men with psoriasis (mean age standard deviation [SD], 47 14 years) and 65 men without psoriasis (mean age SD, 44 13 years). In both groups, we measured the body mass index; blood pressure; and serum concentrations of lipids, uric acid, lipase, interleukins 6 and 18, cortisol, and 25-hydroxyvitamin D-3. All participants completed the Beck Depression Inventory. Other variables analyzed included psoriasis duration, the Psoriasis Area Severity Index, and the percentage of body surface area affected by psoriatic lesions. Results Compared with controls, patients with psoriasis had significantly greater depression severity, higher body mass indices, and higher serum concentrations of total cholesterol and interleukins 6 and 18; moreover, they had significantly lower serum 25-hydroxyvitamin D concentrations. In patients with psoriasis, depression severity correlated positively with psoriasis duration, the Psoriasis Area Severity Index, the percentage of body surface area affected by psoriatic lesions, and interleukin-18 concentration. In patients with psoriasis, depression severity correlated negatively with 25-hydroxyvitamin D-3 concentration, but it did not correlate significantly with the serum concentrations of interleukin 6 and cortisol. Conclusions High concentrations of interleukin 18 and low concentrations of 25-hydroxyvitamin D-3 may be associated with depression severity in men with psoriasis. Thus, further studies should examine whether effective anti-inflammatory treatments or vitamin D-3 supplementation can improve depression outcomes in these patients.