Detection of mild cognitive deficits in Parkinson's disease patients with the WAIS-R NI.

The relative insensitivity of traditional IQ tests to mild cognitive deficits has led investigators to develop a version of the widely used Wechsler intelligence scales that allows quantitative analysis of underlying qualitative responses. This instrument, the Wechsler Adult Intelligence Scale-Revised as a Neuropsychological Instrument (WAIS-R NI) was administered to 16 Parkinson's disease (PD) patients and 30 normal controls (NC). The 2 groups did not differ significantly in mean age or education, or on their mean Mattis Dementia Rating Scale score. Relative to NC participants, PD patients showed decreased visual attention span, longer response latencies, slower visuomotor processing, and more stimulus-bound errors. Many of the WAIS-R NI measures were able to detect cognitive impairment in a greater percentage of patients than the traditional WAIS-R measures, making it easier to identify deficits that could affect quality of life early in the course of the disease.

Neuropsychological and motor functioning after unilateral anatomically guided posterior ventral pallidotomy. Preoperative performance and three-month follow-up.

This study presents baseline and 3-month follow-up motor and neuropsychological data for 22 patients with Parkinson's disease (PD) who underwent anatomically guided unilateral posterior ventral pallidotomy (PVP). Postsurgical improvements were seen in psychomotor speed, fine motor accuracy, and dyskinesia, whereas grip strength decreased on the side contralateral to the surgery. No change was detected in overall level of cognitive functioning, nor were changes demonstrated in memory, language, or working memory when the entire sample of patients was evaluated. When the group was divided on the basis of side of surgery, patients with left-sided pallidotomies showed a decline in verbal fluency. Patients and caregivers reported improvement in psychosocial functioning. These initial findings of improved motor performance and largely unaffected cognitive functions are consistent with results obtained with functional PVP and provide support for the use of anatomically guided posterior ventral pallidotomy in the treatment of motor symptoms of PD.

Structural MRI correlates of recognition memory in Alzheimer's disease.

Neuroimaging and lesion studies have demonstrated that hippocampal volume correlates with memory performance, but material-specific lateralization of this structure-function relationship has been inconsistent. This MRI study examined the relative contributions of left and right temporal lobe volumes to verbal and nonverbal recognition memory in a group of 20 Alzheimer's disease (AD) patients. There was a significant relationship between extent of right hippocampal and right temporal gray matter tissue volume deficit and performance on the face recognition subtest of the Warrington Recognition Memory Test. The face recognition test correlated with right hemisphere volume but not to left, indicating a material-specific relationship between brain structure and function in this patient group. Right temporal horn volume did not account for a significant proportion of variance in face recognition memory. Although word recognition was not significantly correlated with either left or right hippocampal volume in the total group, there was a strong correlation between left hippocampal volume and word recognition memory in the female AD patients. Thus, face recognition shows a material specific relationship with select lateralized hippocampal and temporal cortical volumes in AD patients, regardless of gender, whereas the verbal recognition-left-hippocampal volume relationship may be mediated by gender.

Differential contributions of cognitive and motor component processes to physical and instrumental activities of daily living in Parkinson's disease.

Patients with Parkinson's disease (PD) become dependent upon caregivers because motor and cognitive disabilities interfere with their ability to carry out activities of daily living (ADLs). However, PD patients display diverse motor and cognitive symptoms, and it is not yet known which are most responsible for ADL dysfunction. The purpose of this study was to identify the contributions that specific cognitive and motor functions make to ADLs. Executive functioning, in particular sequencing, was a significant independent predictor of instrumental ADLs whereas simple motor functioning was not. By contrast, simple motor functioning, but not executive functioning, was a significant independent predictor of physical ADLs. Dementia severity, as measured by the Dementia Rating Scale, was significantly correlated with instrumental but not physical ADLs. The identification of selective relationships between motor and cognitive functioning and ADLs may ultimately provide a model for evaluating the benefits and limitations of different treatments for PD.

Non-associative lexical priming is impaired in Alzheimer's disease.

A word-fragment completion task was used to assess long-term, non-associative lexical priming in patients with probable Alzheimer's disease (AD) and age- and education-matched elderly normal control (NC) subjects. Despite equivalent baseline performance, the AD patients exhibited less facilitation in their ability to complete word fragments from having previously read the intact words than did the NC subjects. The AD patients were also impaired relative to NC subjects on an explicit recognition memory task, but there was no relationship between explicit memory performance and priming for either group. These results are consistent with previous demonstrations of impaired semantically-based priming in patients with AD and extend the domain of their impairment to priming that is predominantly based on lexical activation.

A population-based analysis of qualitative features of the neuropsychological test performance of individuals with dementia of the Alzheimer type: implications for individuals with questionable dementia.

Qualitative features of the neuropsychological test performance of individuals with dementia of the Alzheimer type (DAT) were examined in a population-based study. Qualitative error scores were derived from measures of verbal and figural memory, verbal fluency and confrontation naming for 38 patients with clinically diagnosed DAT, 236 normal elderly (NE) individuals, and 72 others who were questionably demented and at risk (AR) for DAT. Persons with DAT made a greater proportion of intrusion and perseverative errors, and more lexical and semantic naming errors, than the NE participants. These measures provided fair specificity but poor sensitivity for the diagnosis of DAT, and a logistic model based on these measures correctly classified 98% of the NE participants, but only 29% of the DAT participants. The AR participants demonstrated a pattern of errors that was highly similar to that of the DAT patients, and when their scores were subjected to the logistic model, 90% were classified as NE and 10% as DAT. These results indicate that specific error types that have been associated with DAT in self-referred or clinic-based samples also occur in the general population to a greater degree in individuals with DAT or questionable dementia than in NE individuals. Furthermore, these qualitative features may have some diagnostic usefulness in that their presence provides reasonable specificity for DAT or questionable dementia.

Subcortical hyperintensities on MRI and activities of daily living in geriatric depression.

Data from 30 elderly inpatients with major depression were analyzed to explore the relationship between subcortical hyperintensities (SH) on MRI and activities of daily living (ADLs). A comparison of subjects based on a median split of the severity of SH revealed that subjects with greater SH performed worse on both instrumental and physical ADLs. A hierarchical multiple regression revealed that age, depression severity, neuropsychological test performance, and SH variables accounted for a total of 53% of the variance in ADL functioning. Severity of SH accounted for an additional 18% of the variance over and above the other three variables. Results suggest that severity of subcortical disease measured by MRI improves prediction of functional impairment in elderly individuals.

Screening for dementia of the alzheimer type in the community: the utility of the Clock Drawing Test.

This study reports the sensitivity and specificity of the Clock Drawing Test (CDT) for detecting dementia of the Alzheimer type in a community-dwelling sample of elderly subjects. Forty-two patients with clinically diagnosed Alzheimer's disease and 237 cognitively intact subjects were administered the CDT as part of an epidemiological study of aging and dementia. Three individual measures of clock drawing performance (quantitative score, qualitative score, and combined quantitative and qualitative score) were determined for each participant. When qualitative elements such as errors and strategies were incorporated into the CDT score, the sensitivity was 84% and the specificity was 72%. The findings suggest that a CDT score which evaluates qualitative and quantitative features provides reasonably good discrimination between normal elderly individuals and DAT patients. However, the CDT appears to have limited utility as a single screening instrument in the community. Instruments such as the Dementia Rating Scale (Mattis, 1976) provide better discrimination of DAT, indicating that functions such as memory and verbal fluency need to be assessed during screening.

Clinical validity of the Mattis Dementia Rating Scale in detecting Dementia of the Alzheimer type. A double cross-validation and application to a community-dwelling sample.

OBJECTIVE: To assess the clinical validity of the Dementia Rating Scale (DRS) in detecting patients with dementia of the Alzheimer type (DAT). BACKGROUND: The DRS is widely used to evaluate cognitive functioning in older adults. Adequate normative data are unavailable; studies addressing the clinical validity of the DRS are limited by small sample sizes. DESIGN AND METHODS: Administered the DRS to 254 outpatients with DAT and 105 healthy elderly subjects. Performed (1) multiple regressions of demographic factors on the DRS and its subscales; (2) derivation of optimal DRS cutoff scores using receiver operating characteristic curves; (3) double cross-validation with stepwise logistic regressions; and (4) application of results to a community-dwelling sample. RESULTS: Age- and education-adjusted DRS scores were computed. The optimal DRS cutoff score for DAT of 129 or less revealed a sensitivity of 98% and a specificity of 97%. The logistic regressions resulted in a combination of the Memory and Initiation/Perseveration subscales that correctly classified 98% of all subjects, 92% of a subsample of 76 patients with mild DAT, and 100% of the 51 patients with autopsy-confirmed DAT. The resultant equation was then applied to a community-dwelling sample (238 healthy elderly subjects and 44 patients with DAT): 91% of patients and 93% of normal subjects were correctly classified. Of an additional 77 individuals with questionable DAT, 43 were classified as demented and 34 were classified as nondemented. CONCLUSIONS: The DRS is a clinically valid psychometric test for the detection of DAT. The Memory and Initiation/Perseveration subscales are its best discriminative indexes for an abbreviated version.

Detection of dementia of the Alzheimer type in a population-based sample: neuropsychological test performance.

The ability to detect dementia of the Alzheimer type (DAT) in a community-dwelling sample of elderly individuals on the basis of neuropsychological test performance was examined. Three hundred sixty community-dwelling individuals were identified by neurological examination as having probable or possible Alzheimer's disease, being at risk for Alzheimer's disease, or having no cognitive impairment. A logistic model comprised of tests of verbal and nonverbal memory, mental flexibility, and confrontation naming correctly classified 82% of DAT subjects and 98% of normal elderly subjects. The logistic model classified 77% of subjects who were diagnosed as at risk for Alzheimer's disease as being cognitively normal. A cross-validation with a clinically based sample of subjects correctly classified 89% of DAT patients and 100% of normal control subjects. The results suggest that psychometric discrimination of dementia may be less accurate in community-dwelling populations than in clinically based samples.