Neural correlates of cognitive dysfunction in Lewy body diseases and tauopathies: combined assessment with FDG-PET and the CERAD test battery.

We investigated disease-specific cognitive profiles and their neural correlates in Lewy-body diseases (LBD) and tauopathies by CERAD assessment and FDG-PET. Analyses revealed a significant interaction between reduced semantic fluency in tauopathies and impaired verbal learning in LBD. Semantic fluency discriminated between groups with high accuracy (83%). Compared to LBD, tauopathy patients showed bilateral hypometabolism of midbrain, thalamus, middle cingulate gyrus and supplementary motor/premotor cortex. In the reverse contrast, LBD patients exhibited bilateral hypometabolism in posterior parietal cortex, precuneus and inferior temporal gyrus extending into occipital and frontal cortices. In diagnosis-independent voxel-based analyses, verbal learning/memory correlated with left temporal and right parietal metabolism, while fluency was coupled to bilateral striatal and frontal metabolism. Naming correlated with left frontal metabolism and drawing with metabolism in bilateral temporal and left frontal regions. In line with disease-specific patterns of regional glucose metabolism, tauopathies and LBD show distinct cognitive profiles, which may assist clinical differentiation.

Cognitive and motor assessment in autopsy-proven corticobasal degeneration.

OBJECTIVE: To investigate the clinical features of autopsy-proven corticobasal degeneration (CBD). METHODS: We evaluated symptoms, signs, and neuropsychological deficits longitudinally in 15 patients with autopsy-proven CBD and related these observations directly to the neuroanatomic distribution of disease. RESULTS: At presentation, a specific pattern of cognitive impairment was evident, whereas an extrapyramidal motor abnormality was present in less than half of the patients. Follow-up examination revealed persistent impairment of apraxia and executive functioning, worsening language performance, and preserved memory. The motor disorder emerged and worsened as the condition progressed. Statistical analysis associated cognitive deficits with tau-immunoreactive pathology that is significantly more prominent in frontal and parietal cortices and the basal ganglia than temporal neocortex and the hippocampus. CONCLUSION: The clinical diagnosis of corticobasal degeneration should depend on a specific pattern of impaired cognition as well as an extrapyramidal motor disorder, reflecting the neuroanatomic distribution of disease in frontal and parietal cortices and the basal ganglia.