Unaffected siblings of probands with alopecia areata and/or major depressive disorder are also at increased risk for developing alopecia or depression compared with control patients, according to study findings published in the Journal of the American Academy of Dermatology.
This population-based cohort study was designed to investigate bidirectional associations between alopecia areata and major depressive disorder among siblings using data from the Taiwan National Health Insurance program. The study included 2123 probands with alopecia areata, 2298 unaffected siblings, and 9192 matched control patients who were assessed for risk for major depressive disorder. In addition, 16,543 probands with depression, 17,352 unaffected siblings, and 69,408 matched control patients were assessed for risk for developing alopecia areata. Participants were monitored starting on January 1, 1996, and followed until diagnosis of major depressive disorder, death, or the study end on December 31, 2011. Individuals in the control groups were matched for age, gender, monthly income, and urbanization level. Relative risk was adjusted for potential confounders, including age, gender, and socioeconomic characteristics, and calculated using the Breslow-Cox model.
Among the alopecia areata group, 167 (7.87%) probands, 64 (2.79%) unaffected siblings, and 94 (1.02%) control patients developed major depressive disorder. In adjusted analysis, the risk for probands with alopecia developing major depression was 8.22 (95% CI, 6.41-10.54; P <.0001), and the risk for unaffected siblings developing depression was 2.55 (95% CI, 1.91-3.40; P <.0001). Among the major depressive disorder group, 75 (0.45%) probands and 65 (0.37%) unaffected siblings developed alopecia compared with 160 (0.23%) control patients. The risk for probands with major depression developing alopecia areata was 1.66 (95% CI, 1.24-2.22; P =.0006), and the risk for unaffected siblings developing alopecia was 1.64 (95% CI, 1.27-2.12; P =.0002).
Limitations of the study included the prospective nature of the study, making temporality of associations uncertain, as well as the lack of data regarding disease severity, body mass index, smoking status, alcohol use, and stressful life events. Further, it is possible some diagnoses were misclassified. Finally, all participants were Taiwanese, limiting the generalizability of the findings to a broader population.
The investigators suggest that these findings reveal a bidirectional association between alopecia and depression in unaffected siblings and probands. Future research should help elucidate the shared pathogenesis or underlying familial mechanisms of these diseases.
Dai YX, Tai YH, Chen CC, Chang YT, Chen TJ, Chen MH. Bidirectional association between alopecia areata and major depressive disorder among pro bands and unaffected siblings: a nationwide population-based study [published online January 29, 2020]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2019.11.064