NEUROPSYCHIATRIC SYMPTOMS AND ALZHEIMER DISEASE BIOMARKERS PREDICT DRIVING DECLINE

Abstract

Changes in cognitive and neurobehavioral processes begin in the long preclinical stage of Alzheimer disease (AD). In older adults, mood states and neuropsychiatric symptoms (NPS) predict progression to symptomatic AD. We examined whether mood states and NPS interact with cerebrospinal fluid (CSF) biomarkers (β-amyloid42 [Aβ42], tau, phosphorylated tau181 [ptau181], tau/Aβ42 and ptau181/Aβ42) of underlying AD pathology to predict driving decline among cognitively normal older adults. Participants, 65 years of age or older, were enrolled from longitudinal studies at the Knight Alzheimer's Disease Research Center at Washington University. Cox proportional hazards models (CPHM) evaluated whether CSF biomarkers, mood states (Profile of Mood States-Short Form [POMS-SF]; Geriatric Depression Scale [GDS]) and NPS (Neuropsychiatric Inventory Questionnaire) were associated with time to receiving a rating of marginal or fail on the driving test. Age, education and gender were adjusted in the models. Data were available from 116 participants with ages ranging from 65.6 to 88.2 years. There were statistically significant interactions with CSF biomarkers and NPS. Cox proportional hazards models showed that interactions between NPI-Q and Aβ42 (p=0.012), tau/Aβ42 (p=0.033) and ptau181/Aβ42 (p=0.038) biomarkers were significant in predicting time to a rating of Marginal/Fail on the road test (see Figure 1). Participants with NPS and more abnormal levels of Aβ42, CSF tau/Aβ42 and ptau181/Aβ42 were much faster to receive a marginal/fail rating on the road test compared to participants with no NPS or non-abnormal biomarkers. Models examining mood states were not statistically significant.