Interestingly, we found stronger associations between hair cortisone levels and CD4 count than hair cortisol levels did, which was in line with some previous studies that also reported stronger associations between hair cortisone levels and variables studied than hair cortisol levels did, including Parkinson’s disease [39], Cushing’s syndrome [40], cardiometabolic variables [41, 42], and stress-related variables [39, 43]. The gene discussed is CD4; the disease is Parkinson disease.