Probabilistic association learning in frontotemporal dementia and schizophrenia

Introduction: Recent neuropsychological studies show substantial cognitive deficits in patients with frontotemporal dementia (FTD). Schizophrenia (SC) overlaps in terms of neurobehavioural symptoms with FTD. Probabilistic association learning, which is thought to assay fronto-striatal function, is well documented to elicit impairment in SC and has not been investigated in FTD to date; this study compared FTD, SC and a healthy comparison group on probabilistic association learning to determine the extent to which FTD patients were similar in performance to SC patients.

Methods: Twenty FTD patients, 24 SC patients and 26 healthy controls were assessed using the probabilistic association learning weather prediction test. FTD patients were also divided into behavioural and language variants for comparison to the healthy group.

Results: FTD patients were impaired during probabilistic association learning in comparison to healthy controls. There was no difference in performance between the FTD and SC groups. FTD behavioural variants performed significantly worse than the healthy comparison group, while FTD language variants did not differ from the healthy comparison group.

Conclusions: This study provides the first evidence for impaired probabilistic association learning in FTD which is of an equivalent degree to that seen in SC. These results support recent structural neuroimaging studies showing fronto-striatal abnormalities in FTD and suggest that fronto-striatal dysfunction may contribute to cognitive deficits in a significant proportion of people with FTD.