Introduction: The two main variants of Progressive Supranuclear Palsy (PSP), Richardson’s syndrome (PSP-RS) and PSP-parkinsonism (PSP-P), share motor and non-motor features with Parkinson’s disease (PD) particularly in the early stages. This makes the precocious diagnosis more challenging. We aimed at deﬁning qualitative and quantitative differences of neuropsychiatric and neuropsychological proﬁles between PSP-P, PSP-RS and PD patients recruited within 24 months after the onset of symptoms, in order to clarify if the identiﬁcation of peculiar cognitive and psychiatric symptoms is of help for early PSP diagnosis.
Methods: PD (n ¼ 155), PSP-P (n ¼ 11) and PSP-RS (n ¼ 14) patients were identiﬁed. All patients were submitted to clinical, neurological, neuropsychiatric diagnostic evaluation and to a comprehensive neuropsychiatric and neuropsychological battery. Predictors of PSP-P and PSP-RS diagnosis were identiﬁed by multivariate logistic regressions including neuropsychiatric and neuropsychological features that differed signiﬁcantly among groups.
Results: The three groups differed signiﬁcantly at the Apathy Rating Scale score and at several neuro- psychological domains. The multivariate logistic regressions indicated that the diagnosis of PSP-RS was predicted by phonological verbal ﬂuency deﬁcit whereas the presence of apathy signiﬁcantly predicted the PSP-P diagnosis.
Conclusion: Peculiar neuropsychiatric and neuropsychological symptoms are identiﬁable very precociously in PSP-P, PSP-RS and PD patients. Early phonological verbal ﬂuency deﬁcit identiﬁes patients with PSP-RS whereas apathy supports the diagnosis of PSP-P.