Poster 5: An Item Response Analysis of Depressive Symptomatology in Pre-Huntington Disease

Historically, the diagnosis of HD has been based on the presence of motor-related symptoms. There is emerging evidence, however, that prior to the manifestation of motor symptoms sufficient to warrant clinical diagnosis, many patients exhibit subtle motor, cognitive, and psychiatric signs, suggesting that people with HD may experience detectable changes before clinical diagnosis (i.e., pre-HD). There is currently a need for a rating scale that is sensitive enough to detect early symptomatic changes and disease progression in pre-HD. The Functional Rating Scale Taskforce for pre-HD (FuRST-pHD) has been established to develop such a measure. In the initial phase of this program, FuRST-pHD will identify which symptoms should be addressed in a clinical scale, and how best to measure those symptoms. Depression is thought to be a component of HD that may be present prior to clinical diagnosis. In the present study, FuRST-pHD examined the expression of signs and symptoms associated with depression using data obtained from PREDICT-HD, utilizing a non-parametric item response analysis of depression ratings (UHDRS-III, BDI-II). Item response modeling can be used to evaluate the performance of individual items (or symptoms) on rating scales, assessing the relationship between a score assigned to a particular item and overall severity of the disease. The results show that pre-HD CAG-expanded subjects (≥37 repeats, n = 752) reported greater depressive symptomatology compared to the comparison group (