Psychiatric wandering behaviour in dementia patients correlated with increased striatal dopamine D2 receptor as shown by [11C]YM-09151-2 and positron emission tomography

Abstract

It is known that some demented patients show psychiatric symptoms and behavioural abnormalities such as wandering. However, how such behavioural abnormalities are correlated with brain function is unclear. In this study, the relationship between the dopaminergic receptor and psychiatric wandering behaviour in dementia was examined. Nine probable Alzheimer's disease (AD) patients with the NINCDS-ADRDA criteria, nine vascular dementia (VD) patients with the NINDS-AIREN criteria and six age-matched controls were studied. Four of each of the dementia group showed psychiatric wandering behaviour. The dopamine D2 receptor was assessed using the radiolabeled D2 antagonist. [11C]YM-09151-2, and positron emission tomography (PET). A three-compartment analysis using the metabolite-corrected (with HPLC) plasma radioactivity curve was performed for the calculation of receptor kinetics. Time-activity curves of the striatum were obtained. Two-way analysis of variance showed that there was a significant difference in the k3/k4 value between the groups (normal, VD and AD) considering the effect of wandering behaviour (wanderers or not). Post hoc test indicated that the values for AD and VD were greater than those of the controls. Since the k3/k4 value was equal to the binding potential under the tracer condition, the result indicated that psychiatric wandering behaviour of dementia was correlated with increased dopamine D2 receptors.