DRD3 Predicts Cognitive Impairment and Anxiety in Parkinson's Disease: Susceptibility and Protective Effects

Background

A possible genetic contribution of dopamine D3 receptor (DRD3) to cognitive impairment in Parkinson's disease (PD) has yet to be investigated.

Objective

To explore the effects of rs6280 (Ser9Gly) genotype on PD patients' cognitive performance and to clarify possible interactions with psychopathology.

Methods

Two hundred and fifty-three consecutive PD patients underwent neurological and neuropsychological evaluations, which included: Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn & Yahr scale (H&Y), Dementia Rating Scale-2 (DRS-2), and Hospital Anxiety and Depression Scale (HADS). rs6280 polymorphism was genotyped for all PD patients and for 270 ethnically matched healthy volunteers (HC). Non-parametric group comparisons and logistic regressions were used for data analyses.

Results

rs6280 genotype did not differ between PD and HC groups. PD patients with rs6280 CC genotype had more impaired cognitive performance (i.e., <1st percentile of demographically adjusted norms) on DRS-2 subscales Initiation/Perseveration and Construction than those with TT genotype. These associations remained statistically significant when other covariates (e.g., demographic features, disease duration, severity of motor symptoms in OFF and ON states, anti-parkinsonian medication, and psychopathology symptoms) were taken into consideration. PD patients with rs6280 TC had less anxiety (i.e., HADS Anxiety≥11) than those with TT (p = 0.012). This association was also independent of other covariates.

Conclusions

Study findings suggest that rs6280 CC genotype predisposes to executive dysfunction and visuoconstructional deficits, whereas the heterozygous genotype protects from anxiety in PD. These effects do not appear to be dependent of one another. rs6280 is not a genotypic susceptibility factor for PD.

What does the Dementia Rating Scale-2 measure? The relationship of neuropsychological measures to DRS-2 total and subscale scores in non-demented individuals with Parkinson's disease

OBJECTIVE

The Dementia Rating Scale-2 (DRS-2) is recommended for assessing global cognition in Parkinson's disease (PD) by the Movement Disorder Society. However, empirical evidence is limited regarding the degree to which the DRS-2 corresponds to traditional neurocognitive domains (i.e., construct validity) in PD. Thus, this study aims to determine the construct validity of the DRS-2 in a non-demented sample of PD patients.

METHOD

Patients with PD (n = 359; mean age = 64.50 ± 8.53, education = 14.97 ± 2.73, disease duration = 8.48 ± 4.87, UPDRS Part III motor scale scores = 25.23 ± 10.17) completed the DRS-2 as part of a comprehensive neuropsychological assessment consisting of attention/working memory, executive function, language, delayed recall, and visuoperceptual-spatial skills.Bootstrapped bias-corrected Spearman rho's correlations andhierarchical linear regressions were performed to examine construct validity of DRS-2 total and subscale scores.

RESULTS

Speeded measures of set-shifting, rapid word generation to letter and semantic cues, and simple visuoperceptual skills largely accounted for variance in DRS-2 total scores. Most DRS-2 subscale scores showed weak relationships with theoretically related neuropsychological measures.

CONCLUSIONS

DRS-2 total scores reflect impairment across a range of cognitive domains (i.e., executive, language, and visuoperception), while DRS-2 subscale scores have limited construct validity. Together, the DRS-2 does not appear to have utility beyond screening for global cognition in PD.

Normative data for the Dementia Rating Scale-2 in the French-Quebec population

The Dementia Rating Scale-2 is used to measure cognitive status of adults with cognitive impairment, especially of the degenerative type, by assessing five cognitive functions, namely attention, initiation/perseveration, construction, conceptualization, and memory. The present study aimed to establish normative data for this test in the elderly French-Quebec population. A total of 432 French-speaking elders from the province of Quebec (Canada), aged 50 to 85 years, were administered the Dementia Rating Scale-2. Age and education were found to be associated with the total score on the test, while gender was not. Percentile ranks were then calculated for age- and education-stratified groups. Previous studies have shown that cultural background can affect performance on the DRS and the development of culture-specific norms for French-speaking Quebecers could be very useful to clinicians and researchers working with this population.

Preserving cognition through an integrated cognitive stimulation and training program

BACKGROUND

Cognitive decline leads to disability and increased health care expenditures.

METHODS

Effectiveness of an intervention to stimulate multiple cognitive domains was determined using a format combining traditional and computer-based activities (Integrated Cognitive Stimulation and Training Program), 45 minutes a day, 2 days a week, for 6 weeks. Nonimpaired, mildly, and moderately-impaired participants > age 65 (n = 32) were randomly allocated into a control or experimental group. Using a repeated measures design participants were tested again postintervention and at 8 weeks follow-up.

RESULTS

Statistically significant improvement on Dementia Rating Scale scores occurred for mildly and moderately impaired treatment participants (n = 15). Statistical significance was demonstrated on subscales of the WMS-III: Logical Memory I and Logical Memory II.

CONCLUSION

Blending computer-based with traditional cognitive stimulation activities shows promise in preserving cognitive function in elders. Future studies to explore efficacy in larger, more diverse samples are needed.

Distinct cognitive profiles and rates of decline on the Mattis Dementia Rating Scale in autopsy-confirmed frontotemporal dementia and Alzheimer's disease

Neuropsychological studies have shown that patients with Frontotemporal dementia (FTD) perform worse than patients with Alzheimer's disease (AD) on tests of conceptualization and verbal fluency, but better on tests of memory and visuospatial functions. However, it is not known if these distinct cognitive profiles are robust enough to be detected using a relatively brief dementia screening instrument such as the Mattis Dementia Rating Scale (MDRS). To address this issue, the MDRS subscale profiles of patients with autopsy-confirmed FTD (n = 17) or AD (n = 34) were compared. Results showed distinct cognitive profiles in which FTD patients performed worse than AD patients on the Initiation/Perseveration and Conceptualization subscales while performing better on the Memory and Construction subscales. The distinct subscale profiles correctly classified 85% of AD patients and 76% of FTD patients. Profiles were maintained in a subset of mildly-to-moderately demented patients (MDRS > or = 105) and correctly classified 89% of these patients. In addition, FTD patients (mean = 30.0 points/year) declined faster than AD patients (mean = 14.8 points/year) on MDRS total and specific subscale scores. These results suggest that the MDRS may be a useful adjunct to other clinical measures for distinguishing FTD from AD and tracking the progression of the disorder.

Development of a Brief Cognitive Screen for Mild Cognitive Impairment and Neurocognitive Disorder

The purpose of this study was to develop and evaluate a brief cognitive screen for possible Mild Cognitive Impairment (MCI) and other neurocognitive impairment in a sample of general medical patients. Two hundred community-dwelling general medical patients aged 65 or older participated in this study. Age and education corrected scores from the Rey Auditory Verbal Learning Test and Mattis Dementia Rating Scale were used to classify participants into three groups: MCI, neurocognitive disorder, cognitively intact. Groups were then compared on an independent set of measures: the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery, Mini-Mental State Examination, and Clock Drawing Test. The MCI group constituted 9% of the sample, while 10.5% of the sample was classified into the neurocognitive disorder group. The CERAD Verbal Category Fluency and CERAD Word List Memory Test Delayed Recall measures were individually and collectively the most effective in differentiating cognitively intact elders from persons in both the MCI and neurocognitive disorder groups. We conclude that these two brief measures appear to be effective for detecting possible MCI or neurocognitive disorder, thereby facilitating identification of candidates who would benefit from more detailed neuropsychological assessment.

Fine Tuning Recommendations for Older Adults with Memory Complaints: Using the Independent Living Scales with the Dementia Rating Scale

The purpose of this study was to describe how functional test performance changed as global cognitive functioning dropped, as well as to examine the relationship of demographic variables and depression with functional test results. We found that level of performance on the Independent Living Scales (ILS) correlated highly with Dementia Rating Scale (DRS) scores in 83 older adults presenting for clinical neuropsychological assessment, while correlations with demographic factors and depression were nonsignificant or modest. Based on DRS scores, we divided our sample into four groups: normal cognitive status, borderline cognitive impairment, likely mild dementia, and likely moderate dementia. ILS profiles of the borderline impairment and mild dementia groups were similar and reflected particularly poor performance on subscales tapping financial management and everyday memory. Individuals with likely moderate dementia were markedly impaired on all subscales.

Screening of dementia in stroke patients with lacunar infarcts: comparison of the mattis dementia rating scale and the mini-mental state examination

There have been no data on the performance of the Initiation-Perseveration subtest of the Mattis Dementia Rating Scale (MDRS-IP) in screening poststroke dementia (PSDE). Three months after the index stroke, a research assistant administered the MDRS-IP and Mini-Mental State Examination (MMSE) to 83 Chinese stroke patients with lacunar infarcts who were consecutively admitted to the stroke unit of a general hospital. A psychiatrist, who was blind to the MDRS-IP and MMSE scores, interviewed all 83 patients and made a Diagnostic and Statistical Manual of Mental Disorders (4th edition) diagnosis of dementia, which served as the benchmark for judging the performance of MDRSIP. The optimal cutoff point of MDRS-IP was 22/23. The sensitivity, specificity, and positive and negative predictive values of MDRS-IP, and the area under the receiver operating characteristic curve were 82%, 90%, 0.41, 0.98, and 0.91, respectively. The overall performance of the MDRS-IP was comparable to the MMSE.

Choline acetyltransferase activity and cognitive domain scores of Alzheimer's patients

Choline acetyltransferase activity and cognitive domain scores of Alzheimer's patients. Item scores from the Mattis Dementia Rating Scale (MDRS) and the Mini-Mental State Examination (MMSE) from 389 patients with probable Alzheimer's disease were submitted to principal component analysis with orthogonal rotation. The optimal solution identified four factors that reflected the cognitive domains of attention/registration, verbal fluency/reasoning, graphomotor/praxis and recent memory. A subgroup of patients was identified for whom both the MDRS and the MMSE had been administered within the 12 months before death. Scores were assigned to these patients for the four factors. These cognitive-domain scores were then correlated with postmortem choline acetyltransferase (ChAT) activity in the medial frontal cortex, inferior parietal cortex, and hippocampus. ChAT activity in both the medial frontal and the inferior parietal cortex significantly correlated with scores on the graphomotor/praxis factor. Medial frontal ChAT also correlated significantly with the attention/registration scores. Hippocampal ChAT correlated significantly only with recent memory scores. These results are consistent with current animal research regarding the effect of selective cholinergic lesions on behavior.

Neuropsychological functioning and MRI signal hyperintensities in geriatric depression

OBJECTIVE

The purpose of this study was to examine the relationship between signal hyperintensities--a probable marker of underlying pathology--on T2-weighted magnetic resonance brain scans and neuropsychological test findings in elderly depressed and normal subjects.

METHOD

Elderly subjects with a DSM-III-R diagnosis of major depression (N=41) and normal elderly comparison subjects (N=38) participated in a magnetic resonance imaging study (1.0-T) of signal hyperintensities in periventricular, deep white matter, and subcortical gray matter. Hard copies of scans were rated in random order by research psychiatrists blind to diagnosis; the modified Fazekas hyperintensity rating scale was used. Cognitive performance was independently assessed with a comprehensive neuropsychological battery. Clinical and demographic differences between groups were assessed by t tests and chi-square analysis. Relationships between neuropsychological performance and diagnosis and hyperintensities and their interaction were analyzed by using analysis of covariance, with adjustment for age and education.

RESULTS

Elderly depressed subjects manifested poorer cognitive performance on several tests than normal comparison subjects. A significant interaction between hyperintensity location/severity and presence/absence of depression on cognitive performance was found: depressed patients with moderate-to-severe deep white matter hyperintensities demonstrated worse performance on general and delayed recall memory indices, executive functioning and language testing than depressed patients without such lesions and normal elderly subjects with or without deep white matter changes.

CONCLUSIONS

Findings validate cognitive performance decrements in geriatric depression and suggest possible neuroanatomic vulnerabilities to developing particular neuropsychological dysfunction in depressed subjects.