P4‐110: Potential of PET to predict cognitive decline along the continuum of Alzheimer's disease

consecutive AD outpatients participated in the study. The cerebral blood flow, the cognitive function and the delusional ideas were assessed by the SPECT using Tc-99m ethylcysteinate dimer (ECD), the Mini Mental State Examination (MMSE) and the BEHAVE-AD-FW. Factor analysis was done for the sub-categories of the delusion part of the BEHAVEAD-FW. For each sub-category and each factor derived by the factor analysis, the SPECT images of the delusion-positive cases were compared against those without delusion. SPECT images were analyzed by SPM5. Results: Of the 85 cases, 48 were positive for one or more category (ies) of the delusion, where MMSE score was not significantly different between positive and negative cases. The factor analysis derived 3 factors, where the factor 1 included “Stealing things” and “abandonment”, the factor 2 included “caregiver is imposter” and “suspiciousness / paranoia”, and the factor 3 included “infidelity”. Radioisotope (RI) uptake was significantly smaller at right temporal pole and inferior temporal gyrus for the factor 1, right temporal pole for the factor 2 and 3, right insula for “abandonment”, bilateral amygdala for “Residence is not home”, and right temporal pole and inferior temporal gyrus for the overall 48 delusion-positive cases (P < 0.001 uncorrected). Conclusions: Involvement of right temporal pole, insula, and inferior temporal gyrus may correspond to the deterioration in social cognition, social emotion, and cognition of object features including face perception respectively. Involvement of amygdala may suggest the anxiety underlying the complaint of “Residence is not home”. Distinct combinations of brain regions may underlie distinct types of delusional ideas. BEHAVE-ADFW may be a reasonable and informative method for evaluating the delusional ideas of AD.