Lower Cerebrospinal Fluid Amyloid-β(42) Predicts Sooner Time to Antipsychotic Use in Alzheimer’s Disease

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers of amyloid-β(42) (Aβ(42)) and phosphorylated-tau help clinicians accurately diagnose Alzheimer’s disease (AD). Whether biomarkers help prognosticate behavioral and psychological symptoms of dementia (BPSD) is unclear. OBJECTIVE: Determine whether CSF biomarker levels aid prognostication of BPSD in AD. METHODS: This retrospective cohort study included patients over 65 with a diagnosis of AD based on CSF biomarkers. We measured time from CSF testing to the first antipsychotic use in the following months. We then analyzed time to antipsychotic (AP) use with respect to Aβ(42), total tau, phosphorylated tau, and amyloid-to-tau index using a survival analysis approach. RESULTS: Of 86 AD patients (average 72±5 years, 46.5% male), 11 patients (12.7%) received APs following CSF testing. Patients with Aβ(42) below the median had sooner time-to-AP use. This was significant on a log-rank test (p = 0.04). There was no difference in time-to-AP use if the group was stratified by levels of total tau, phosphorylated tau, or amyloid-to-tau index. CONCLUSION: These results suggest a relationship between lower CSF Aβ(42) levels and sooner AP use. This supports prior reports suggesting a correlation between BPSD and Aβ deposition on PET. These results highlight the need for further prospective studies on Aβ levels and BPSD.