Dissecting the Interplay Between Time of Dementia and Cognitive Profiles in Lewy Body Dementias.

BACKGROUND Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are differentiated by the time of onset of cognitive and motor symptoms ('1-year rule'). We explored the neuropsychological continuum of DLB and PDD subjects with different timing of dementia onset. OBJECTIVE Our aim was to compare the neuropsychological profile of DLB and PDD patients with different timing of dementia onset. METHODS Neuropsychological findings at the diagnosis of dementia of 66 PDD and 42 DLB patients were retrospectively compared. Patients with PDD were divided into three tertile subgroups according to the time interval between the onset of parkinsonism and dementia (N = 24, 2-4 years; N = 17, 5-7 years; N = 25 ≥8 years, respectively). RESULTS DLB patients performed worse on the Stroop and semantic fluency tests than PDD, even in comparison to PD with early dementia onset. No significant differences among PDD subgroups were reported. CONCLUSION Executive and semantic language tests could differentiate DLB and PD patients with earlier development of dementia relative to parkinsonism.