Elevated Tau burden in Amygdala and Hippocampus amongst older participants with psychosis

Abstract

AbstractBackgroundPsychosis is a debilitating cluster of symptoms occurring in some Alzheimer’s Disease (AD) patients, and is defined by the presence of delusions and/or hallucinations. Previous studies suggest that psychosis in AD patients is associated with increased tau burden and accelerated cognitive decline. We sought to assess differences in tau burden between cognitively impaired patients with psychosis(+P) and those without psychosis(‐P).MethodTwenty‐six ADNI participants with psychosis (+P; 11.5% CDR0, 42.3% CDR0.5, 30.7% CDR1, 11.5% CDR2, 4% CDR3, 77±7yr old, 50% women, 16±3yr education, 92% White) and 26 without psychosis were matched by CDR, age, sex, education, and race (‐P; 11.5% CDR0, 42.3% CDR0.5, 30.7% CDR1, 11.5% CDR2, 4% CDR3, 77±6yr old, 54% women, 15±3yr education, 92% White). The +P group was defined based on any endorsement of hallucinations or delusions on Neuropsychiatric Inventory. Flortaucipir PET data were processed according to ADNI methods. Difference in tau burden was assessed using a paired t‐test on the ROI and voxel‐level between +P and ‐P groups in Braak regions as well as the amygdala, hippocampus, and frontal, temporal, and parietal lobes A follow‐up voxelwise t‐test was performed within the +P group between those with and without concurrent symptoms at the time of their scan. Analyses were corrected for amyloid‐level and voxel‐wise analyses were evaluated at p<0.001 without multiple comparisons correction.ResultDescriptively, participant‐level scans demonstrated a variety of tau patterns, often with right laterality. Tau was elevated for +P participants compared to ‐P in the amygdala (0.6 [0.25, 0.96]; p = 0.003) and the hippocampus (0.3 [0.04, 0.55]; p = 0.03), while marginally elevated in the frontal cortex (0.09 [‐0.002, 0.189]; p = 0.06) [Figure1]. Voxel‐wise, elevated tau was localized to the amygdala, hippocampus, thalamus, and right frontal lobe [Figure2]. Additionally, with concurrent delusion symptomatology, elevated tau was localized to Braak III/IV regions [Figure3].ConclusionTau burden in the amygdala may be a potential biomarker of psychosis across the AD continuum. Right‐sided laterality is consistent with psychosis‐related structural changes and psychosis‐related tau binding needs to be assessed further. Given that early psychosis in AD is associated with faster cognitive decline, these results could inform the development of prognostic biomarkers.