RELATIONSHIP OF HAIR CORTISOL CONCENTRATION WITH HISTORY OF PSYCHOSIS, NEUROPSYCHOLOGICAL PERFORMANCE, AND EVERYDAY FUNCTIONING IN REMITTED LATER-LIFE MAJOR DEPRESSIVE DISORDER

Abstract

Introduction Psychotic features are more prevalent in older adults with depression than in younger depressed adults. Psychotic major depressive disorder (PMD) is associated with poorer neuropsychological performance and poorer everyday functioning, in both acute and remitted states, compared with non-psychotic major depressive disorder (NPMD). In addition, PMD is also associated with more pronounced dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, including elevated cortisol levels, but it is not known whether this difference between PMD and NPMD persists in remission. The goal of this exploratory study was to test the hypothesis that a history of psychotic features, poorer neuropsychological performance, and poorer everyday functioning were associated with higher cortisol levels in sustained remission of major depressive disorder. If confirmed, it could suggest a possible mechanism for neuropsychological and functional impairment in remitted PMD. In order to examine the relationship between sustained HPA dysfunction in remission and the aforementioned variables, we measured hair cortisol concentration (HCC), a measure of longer-term cortisol exposure. Methods This study used a cross-sectional design and included 60 participants aged 50 years or older with a history of major depressive disorder (n = 17 with NPMD and n = 43 with PMD) in sustained remission and 36 non-psychiatric comparison participants. Hair samples were collected using standardized methods and cortisol concentrations were determined from the first 3-cm hair segment most proximal to the scalp, or from as much hair as was available for participants with shorter hair. This hair segment represents the hair growth over the 3-month period prior to the sampling. HCC was measured in a research laboratory with extensive experience in this analysis using a validated high sensitivity enzyme immunoassay (EIA) that is standard in the field. In order to examine the relationships between HCC and i) history of psychotic features, ii) neuropsychological performance (processing speed, executive function, and verbal memory), and iii) everyday functioning (participant-report general functioning and observer-rated IADL performance), we performed three sets of correlation analyses, one for each variable of interest (point biserial for psychosis history and HCC; Pearson's r for neuropsychological and functional measures). We calculated effect sizes and 95% confidence limits in order to compare HCC results between patient and non-psychiatric comparison groups. HCC data were highly skewed and were log transformed for all analyses. Results NPMD and PMD groups had mean (SD) HCCs of 18.86 (32.97) pg/mg and 12.48 (11.26) pg/mg, respectively. The correlation between HCC and history of psychosis was weak (r = -0.02), as were the correlations between HCC and the neuropsychological measures (r ranging between -0.11 and 0.1). The correlations between HCC and i) IADL performance (r = -0.04) and ii) general functioning (r = -0.074) were also weak. None of these correlations were statistically significant. The mean (SD) HCC for non-psychiatric comparison subjects was 13.86 (20.06) pg/mg. Both effect sizes for the difference between the clinical and non-psychiatric comparison groups were small (0.26 for NPMD versus Comparison group and 0.25 for PMD versus Comparison group). Conclusions This is the first study to assess HCC in PMD and to examine the relationship between HCC and cognition and between HCC and everyday functioning in MDD. We did not find a correlation between HCC and history of psychosis, neuropsychological performance, or functioning in later-life patients with MDD in sustained remission. Further, there was no substantial difference in mean HCC between the patient and non-psychiatric comparison group. There is variability in the literature regarding HCC in MDD and regarding the relationship between HPA-axis function and neuropsychological performance in remitted MDD. Our findings will be discussed in this context. This research was funded by This study was funded by a research grant from the University Health Network Centre for Mental Health ($14,000)