Objective: A consistent body of research has confirmed that patients with major depressive disorder (MDD) have increased concentrations of pro-inflammatory cytokines, including IL-6, TNF-α, IL-1β, the soluble IL-2 receptor, and C-reactive protein, compared to controls; however, there is limited information on IL-17A in MDD. Moreover, information about IL-17A in older populations, i.e., patients with late-life depression (LLD), is conspicuously missing from the literature. The purpose of this study was to investigate the role of IL-17A in LLD. Methods: A convenience sample of 129 individuals, 74 with LLD and 55 non-depressed controls, were enrolled in this study. The Mann-Whitney U test was used to compare plasma IL-17A levels between LLD and controls subjects, and Spearman’s rank order correlation was used to investigate correlation of these levels with clinical, neuropsychological, and cognitive assessments. Results: Plasma IL-17A levels were not statistically different between LLD patients and controls (p = 0.94). Among all subjects (LLD + control), plasma IL-17A did not correlate significantly with depressive symptoms (rho = -0.009, p = 0.92) but a significant correlation was observed with cognitive assessments (rho = 0.22, p = 0.01). Conclusion: Our findings do not support an association between plasma IL-17A levels and LLD. Nevertheless, IL-17A may be associated with cognitive impairment in LLD patients. If this finding is confirmed in future longitudinal studies, modulation of the T-helper 17 cell (Th17) immune response may be a treatment target for cognitive impairment in this population.

Objective: To determine the sensitivity and specificity of three depression screening scales to diagnose major depressive episodes in the elderly. Methods: Participants (n=129, 88% female) answered a semi-structured psychiatric interview (Mini International Neuropsychiatric Interview) to determine the diagnosis of major depressive disorder. After this, depressive symptoms in depressed and non-depressed subjects were assessed by independent administration of the 15-item Geriatric Depression Scale (GDS-15), Patient Health Questionnaire-9 (PHQ-9), and 17-item Hamilton Rating Scale for Depression (HDRS-17). Results: Patients with major depression and controls did not differ in age and gender distribution. The sensitivity and specificity of all scales to identify a major depressive episode in older adults were ≥ 90%. There were no significant differences between the areas under the curve for PHQ-9 vs. HDRS-17 (z = 1.2, p = 0.2), PHQ-9 vs. GDS-15 (z = 0.26, p = 0.8), or HDRS-17 vs. GDS-15 (z = 1.2, p = 0.2). Conclusion: This study provides evidence supporting the use of PHQ-9 and GDS-15, both of which are simple to administer and easy to interpret, to diagnose major depressive episodes in older adults without neurocognitive disorders.