Behavioural and neuropsychological correlates of frontal lobe features in dementia

Background. In order to characterize frontal lobe features and their behavioural and cognitive correlates across diagnostic categories, we performed a cross-sectional analysis of behavioural and neuropsychological data from a large, prospective Belgian study on behavioural and psychological signs and symptoms of dementia (BPSD). Method. Patients with probable Alzheimer's disease (AD) (n = 170), frontotemporal dementia (FTD) (n=28), mixed dementia (MXD) (n=29) and dementia with Lewy bodies (DLB) (n=21) were included and underwent neuropsychological and behavioural assessment by means of a battery of tests and scales. Frontal lobe symptoms were quantified by means of the Middelheim Frontality Score (MFS). Results. In AD (and to a lesser extent in MXD), MFS total scores were negatively correlated with scores on MMSE (Spearman: r = -0(.)36, p < 0(.)001) and a Verbal Fluency Task (r=-0(.)38, p < 0(.)001) and were associated with increased severity and frequency of psychosis (r= 0(.)24, p < 0(.)01), activity disturbances (r=0(.)44, p < 0(.)001) and aggressiveness (r=0(.)43, p < 0(.)001). In DLB, MFS total scores were negatively correlated with MMSE scores (r=0(.)50, p = 0(.)020). No associations were found in FTD patients. Conclusions. A cross-sectional analysis of frontal lobe features, behavioural characteristics and neuropsychological data demonstrated that, in AD (and to a lesser extent in MXD) patients, frontal lobe symptoms were associated with more pronounced cognitive deficits (of frontal origin), with increased severity and frequency of agitated and aggressive behaviour, and with increased severity of psychosis and depressive symptoms. Given the small sample sizes of the DLB and FTD patient groups, negative findings in these patient groups should be interpreted cautiously.