Evaluation of individuals with glucoserabrosidase (GBA) gene mutation with neuropsychological tests and neuroimaging methods

The aim of this study is to investigate whether asymptomatic heterozygous GBA mutation carriers who have a risk of Parkinson's Disease and Lewy Body Dementia are cognitively differentiated from a healthy control group. A 16-person GBA mutation group was matched with an 18-person healthy control group in terms of gender, age and education. Their neuropsychological test performances were compared. It was also examined whether neuropsychological test performances in the GBA mutation group showed a correlation with functional magnetic resonance neuroimaging measurements. The neuropsychological tests were determined to evaluate five different cognitive areas: attention, executive functions, memory, visiospacial functions and language. When the test scores were examined individually, it was found that some test performances of the GBA mutation group in executive functions were significantly lower than those of the healthy control group. One of their scores on tests related to attention and memory, respectively, were also lower than those of the control group. When two groups were compared in terms of composite scores, it was found that the performance of the GBA group related to executive functions was significantly lower again. The bilateral caudate nucleus, anterior and posterior putamen were selected as the seed region for neuroimaging measurements. In GBA mutation group, the functional connectivity of the left posterior putamen with some cortical areas was correlated negatively with composite score of executive functions, but possitively with composite scores of verbal fluency and memory. The results are discussed in the context of the literature on Parkinson's disease and Lewy body dementia. Key Words: heterozygous GBA mutation, neuropsychology, neuroimaging, Parkinson's disease, Lewy body dementia.