Neuropsychology, neuroimaging or motor phenotype in diagnosis of Parkinson's disease-dementia: which matters most?

Validation of Neuropsychological Tests to Screen for Dementia in Chinese Patients With Parkinson's Disease

To compare the accuracy of different neuropsychological tests and their combinations for deriving reliable cognitive indices for dementia diagnosis in Parkinson's disease (PD). One hundred forty consecutive patients with PD were recruited and administrated an extensive battery of neuropsychological tests. Discriminant analysis and receiver-operator characteristic curve were used to evaluate their correct classifications and validity. Patients with PD having dementia (PDD; 23.5%) performed significantly worse in all tests than patients without dementia. Age of onset, disease duration, Hoehn-Yahr grade, Unified Parkinson's Disease Rating Scale part III scores, and education were associated with dementia in patients with PD. Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment, and Block Design (BD) showed better specificity and sensitivity when used alone, and combined use of MMSE and BD further increased the validity. Our results indicated that the accuracy of MMSE was better in dementia diagnosis of Chinese patients with PD, and combined use of MMSE and BD could further increase the validity of dementia diagnosis.

Parkinson's disease dementia: Diagnostic criteria and risk factor review

Cognitive impairment in Parkinson's disease (PD) greatly affects the morbidity and mortality rates of the disease and can be present as mild executive dysfunction even in the early stages. In advanced PD, the prevalence of dementia (PDD) reaches more than 80%. The Movement Disorders Society (MDS) has proposed diagnostic criteria for PDD and Mild Cognitive Impairment (MCI) in PD, raising the sensibility and specificity of those diagnoses compared with DSM IV, for example. Cognition impairment is an important issue to determine in PD because of therapeutic, epidemiologic, and prognostic factors. These guidelines should be applied to a diagnosis of PD-MCI and PDD as soon as possible in order to provide a correct diagnosis. Another important topic to discuss regarding cognition in PD is which patient would be more likely to develop PDD. There are some risk factors for cognitive impairment in PD with cumulative risk. Important risk factors related to PDD are age, time of diagnosis, rigid-akinetic phenotype, severe impairment, impairment of semantic fluency, genetic factors, low education level, and postural instability. Recognizing them is also important for early diagnosis. We discuss the diagnostic criteria of PD cognitive impairment and some aspects of risk factors related to it in this review.

CERAD test performance and cognitive impairment in Parkinson's disease

OBJECTIVES

Many patients with Parkinson's disease (PD) develop mild cognitive impairment (PD-MCI) and dementia (PDD). The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neurocognitive test battery was originally developed to identify early Alzheimer's disease, but it has become a widely used screening instrument also for other types of dementia. The aim of the study was to examine differences in CERAD test performances between cognitively intact and impaired PD patients.

MATERIALS AND METHODS

Eighty-eight PD patients participating in a rehabilitation course were studied. The Clinical Dementia Rating (CDR) was used to assess cognitive impairment. Sixty-six patients were cognitively intact and 22 had cognitive impairment (≥1 in two or more domains or a sum of boxes score of ≥3). The Finnish CERAD test battery was used to measure cognitive functions in seven different domains (language functions, verbal learning, visuospatial functions, delayed recall, memory consolidation, recognition memory, and executive functions).

RESULTS

There were significant differences between the cognitively intact and impaired patients in six CERAD subtests (wordlist learning sum, wordlist delayed recall, constructional praxis recall, clock drawing, verbal fluency and constructional praxis copy) when controlling for covariates (disease duration, motor symptoms, age, and education). No differences were observed in memory consolidation scores.

CONCLUSIONS

The results indicate that mild cognitive impairment in PD is related to deficits in memory, executive functions, and visuospatial functions. The memory deficit is non-amnestic and does not entail accelerated forgetting. CERAD shows promise in identifying PD patients with cognitive impairment and increased risk of dementia.