Overlap between Frontotemporal Dementia and Dementia with Lewy Bodies: A Treviso Dementia (TREDEM) Registry Case Report

In the present work, we report the case of a patient presenting signs of Lewy body dementia (DLB) and frontotemporal dementia (FTD) throughout different phases of the disease. In January 2017, a 79-year-old right-handed living man was admitted to our Memory Clinic for the presence of behavioral disturbances and progressive cognitive decline. For the previous six years, he was monitored by other Neurological Clinics for the onset of extrapyramidal features. Indeed, through the first phase of the disease (2011-2014), the patient predominantly showed: extrapyramidal features, initial cognitive decline, sleep disturbances, and visual hallucinations, together with a reduced dopamine transporter uptake in basal ganglia at the DATscan, suggesting a diagnosis of DLB. In a second phase (2015-2017), while his extrapyramidal features remained substantially stable, his cognitive profile deteriorated, with an additional development of severe behavioral and neuropsychiatric disturbances. Again, a subsequent DATscan study was positive and slightly worse than the preceding one; however, the 18 F-FDG PET showed reduced metabolic activity in the frontal and temporal lobes, with the occipital regions left spared. Genetic analysis revealed a hexanucleotide expansion in C9ORF72 (6//38 repeats; ITALSGEN NV <30). In conclusion, we report the case of a patient presenting, firstly, with probable DLB and, in a second phase, with predominant bvFTD features with stable parkinsonism. Even though some clinical and neuropsychological aspects can co-exist in different neurodegenerative diseases, we find such a significant intersection of clinical features to be fairly atypical. Moreover, what is challenging to define is whether the two clinical phenotypes are somehow lying on a continuum, or if they are two individual entities.