Neuroimaging of psychosis, agitation, and affective disturbance in Alzheimer's disease, dementia with Lewy bodies, and mild cognitive impairment.

Objectives: This study identifies neuropsychiatric syndromes and investigates their relationship with neuroimaging in Alzheimer's disease dementia (AD), dementia with Lewy bodies (DLB), and mild cognitive impairment (MCI).

Methods: Magnetic resonance imaging and perfusion single-photon emission computed tomography data were collected for 281, 68, and 180 patients with AD, DLB, and MCI, respectively, from three Japanese institutions. Neuropsychiatric Inventory was used for exploratory factor analysis in each group. Statistical Parametric Mapping was exploited to reveal the relationships between each factor score and cerebral volume or perfusion with age, sex, dementia severity, and the other factor scores as covariates.

Results: Three factors (psychosis, agitation, and affective disturbance) were extracted for AD. For DLB, nighttime behavior and aberrant motor behavior were extracted as independent symptoms with the same three factors. Four factors (psychosis, agitation, anxiety, and apathy) were extracted for MCI. A positive relationship between agitation and cerebral volume in the left middle frontal gyri and left caudate was observed in AD. In DLB, agitation was positively correlated with cerebral perfusion in the left dominant regions, including the middle frontal gyri and caudate. Psychosis and perfusion were negatively correlated in the left extent regions, including the temporo-parieto-occipital lobe, insula, and inferior frontal gyri in DLB. Psychosis was significantly associated with lower perfusion in the bilateral occipital lobes, whereas apathy was significantly correlated with a lower volume of the right dominant bilateral frontal lobes in MCI.

Conclusions: Three neuropsychiatric syndromes - psychosis, agitation, and affective disturbance - may heterogeneously associate with AD, DLB, and MCI.