Neuropsychological testing in the diagnosis of dementia

Neuropsychological testing can play a major role in the diagnosis of dementia by documenting cognitive deficits, the key criteria for the diagnosis. Because the most common dementia diagnosis, Alzheimer's disease, focuses on memory impairment, tests to assess this domain and to detect and characterize memory deficit are well established with recognized predictive value. Other neuropsychological domains are less well characterized and there are fewer tools to assess them. One domain that has been characterized as important in a number of other dementias is executive function. Improved neuropsychological assessment and characterization of other domains, such as executive function and attention, may assist in better identifying the pathophysiology of deficits in these areas, perhaps in combination with new technologies such as functional imaging. Finally, improved assessment tools for specific cognitive domains should assist in identifying a broad range of cognitive deficits at earlier stages and ultimately lead to more effective interventions for a wider range of cognitive deficits.     

Neuropsychological assessment of cognitive change in dementia

The problem of long-term assessment of cognitive change in dementia is defined as that of avoiding floor and ceiling effects in testing. Unlike diagnosis, the establishment of norms is viewed as secondary. This perspective allows the formulation of strategic guidlines in devising test batteries for longitudinal studies of cognitive change in dementia. A number of tests complying with these guidelines are described, tapping a wide range of cognitive abilities such as semantic analysis of verbal and visual material, semantic memory, object recognition, visuoconstruction and serial planning.     

Neuropsychological assessment of dementia: state of the art

A comprehensive neuropsychological examination includes an assessment of both cognitive functions and personality characteristics. In order to evaluate dementia, the patient's present as well as the premorbid functioning has to be assessed, which is performed by means of tests, behavioral observations, rating scales, and inquiries. These methods are used for diagnostic purposes, for differential diagnostics, follow-up studies, and for evaluation of treatment effects. Recent research has shown that neuropsychological methods have a high sensitivity and specificity in detection of dementia, utilizing measures of episodic memory. For staging of dementia, episodic memory as well as other cognitive functions are necessary. The effectiveness of dementia differentiation by means of neuropsychological methods varies from quite good regarding frontal lobe degeneration to less good regarding cerebrovascular dementias, probably due to the variation in site, extent, number, and temporal characteristics of the lesion. Future development is required regarding methods for evaluation of premorbid functioning, instruments for assessment of executive functions, and personality characteristics in dementia. Furthermore, brain-behavior studies are needed to learn more about the relation between neuropsychological measures vs neuropathology, neurochemistry, and neuroimaging.     

Neuropsychological assessment in the diagnosis and differential diagnosis of fronto-temporal dementia

Clinical diagnosis of fronto-temporal dementia (FTD) and its rare variants (semantic dementia and primary progressive aphasia) represents a special challenge bearing in mind its difficulties and is important due to therapeutic differences with the most common Alzheimer's dementia. Of note, cholinesterase inhibitors commonly prescribed in Alzheimer's disease are not effective in FTD and a novel drug, memantine, has not been evaluated as yet. Neuropsychological evaluation is an important add-on to neurological, psychiatric and neuroimaging assessments in the clinical diagnosis of FTD. In this paper, we have described characteristics of neuropsychological deficits observed in FTD (such as attention, language, visuospatial and memory impairments) as well as tools used (tests) in clinical practice. Special attention is paid to the utility of neuropsychological examination in the differential diagnosis of FTD versus Alzheimer's disease, vascular dementia and other, less common forms of dementia.     

Neuropsychological strategies for detecting early dementia.

As new and more effective treatments for Alzheimer's disease (AD) emerge, the development of efficient screening strategies in educationally and racially diverse primary care settings has increased in importance. A set of candidate screening tests and an independent diagnostic assessment were administered to a sample of 318 patients treated at a geriatric primary care center. Fifty-six subjects met criteria for dementia. Exploratory analysis led to the development of three two-stage screening strategies that differed in the composition of the first stage or Rapid Dementia Screen, which is applied to all patients over the age of 65. The second stage, applied to those patients who screen positively for dementia, is accomplished with the Free and Cued Selective Reminding Test to detect memory impairment. Using clinical diagnosis as a gold standard, the strategies had high sensitivity and specificity for identifying dementia and performed better for identifying AD than non-AD dementias. Sensitivity and specificity did not differ by race or education. The strategies provide an efficient approach to screening for early dementia.     

Objective assessment of praxis-the oap diagram:-simply testing for dementia

Cognitive assessment schedules for the elderly are often complex, cumbersome or highly dependent on memory function. Performance on visuoconstructive tests, which are often easily undertaken, is not dependent on ‘dominance’ of either hemisphere. Unfortunately, such tests often have complex objective and subjective scoring criteria, making standardization difficult. We have designed a structured diagram and scoring system which proved simple to administer and score and performance on which correlated well with intellectual function on the CAPE, while, unlike the Gibson Spiral Maze (GSM), those without dementia tended not to make any mistakes. Scoring on the GSM was also affected by age and the presence of parietal signs to a greater extent than the OAP, suggesting that the GSM may overestimate cognitive impairment in the population for which it was designed. Some possible uses for the OAP as a new test in the assessment of the elderly are discussed.     

Neuropsychological assessment.

The aging population of the United States and many other countries guarantees that disorders common in elderly persons will continue to become more prevalent. In the past decade or so, we already have witnessed the beginning of this trend, with the rapid rise in the number of patients with degenerative dementia, especially Alzheimer's disease. On another track, sophisticated and timely medical and surgical interventions have produced a growing number of patients who survive serious head injury. These patients are typically young, and may live for many decades after their brain injury. In both examples, a core feature of the condition is impaired cognition and behavior; that is, defects in higher-level capacities such as memory, intellectual function, language, and decision-making. Neuropsychological assessment cannot be viewed as a luxury in cases such as these but rather, as a vital component of the neurodiagnostic evaluation. The neuropsychologist uses a set of standardized instruments to measure cognition and behavior in a comprehensive and precise manner, yielding rich information that may assist in accurate diagnosis, prudent management, and optimal rehabilitation. The neuropsychological examination may provide the only means with which to detect alterations in brain function, as in cases of mild head injury or low-level toxic exposure, which may not be revealed through other procedures. Finally, neuropsychological assessment will continue to play a key role in the scientific programs that are dedicated to advancing our understanding of the neural substrates of complex behavior.     

Neuropsychological tests as discriminators between dementia of alzheimer type and frontotemporal dementia

The aim of this study was to examine whether cognitive test performance alone could distinguish patients with dementia of Alzheimer type (DAT) from those with frontotemporal dementia (FTD). Scores from three neuropsychological tests were used as discriminating variables in 28 cases with postmortem verified diagnoses. The selected tests measured verbal ability, visuospatial ability and verbal memory. Eighty-nine per cent of the sample was correctly classified by discriminant analysis. Evaluating the ability of the obtained discriminant function to differentiate between groups of DAT and FTD in a new, clinically diagnosed sample of 38 cases yielded an overall success rate of 84%. The results suggest that cognitive tests may be helpful for differential diagnosis in the context of a neuropsychiatric examination.     

Neuropsychological assessment for temporal lobe epilepsy surgery

Neuropsychological assessment consists of a comprehensive evaluation of cognitive functioning and most often some evaluation of motor skills and sensory status also. Cognitive functions sampled typically include "intelligence" (IQ tests), attention, language skills, visuospatial abilities, "executive skills" and other abilities associated with frontal-lobe function, and learning and memory. Thus, the assessment samples vary widely among a variety of functions, providing a comprehensive picture of an individual's strengths and weaknesses. The resulting pattern points to the probable site of epileptic focus. Neuropsychological findings also serve to predict the risk for postsurgical cognitive decline and, when performance before and after operation is compared, they provide data on the impact of surgery upon cognitive functioning. Comprehensive evaluation of learning and memory is particularly important in this context, because of the frequency of temporal lobe epilepsy and the prominence of memory dysfunction associated with it. In addition, patients slated for elective surgery may also undergo an intracarotid amobarbital procedure (IAP), which is performed to determine the side of cerebral dominance for language and to test the memory capabilities of each hemisphere alone. All of these specialized neuropsychological tools are discussed in this paper.     

Neuropsychological assessment of malingering

Current problems and neuropsychological assessment strategies of malingering detection (assessment of negative response bias or non-optimal test behaviour) are reviewed. First, the paper discusses major conceptual problems inherent in the definition of malingering, factitious disorders, and somatoform disorders. Traditional and modern test approaches and diagnostic procedures are reviewed. Two case vignettes illustrate the application of particular strategies for malingering assessment. In German speaking countries, malingering research has not yet aroused profound interest comparable to that in English speaking countries. Diagnostic standards and instruments still have to be refined.     

Cortical vs subcortical dementia. Neuropsychological differences

The distinction between cortical and subcortical syndromes of dementia is controversial. Clinical reports suggest that subcortical syndromes (eg, Parkinson's disease) involve less severe intellectual and memory dysfunction and lack the aphasia, agnosia, and apraxia typical of the cortical dementias (eg, dementia of the Alzheimer type). A recent neuropsychological investigation using a standardized procedure failed to confirm the distinction. We examined patients with Alzheimer's disease, patients with Parkinson's disease, and normal controls by using a neuropsychological procedure specifically designed to quantitatively evaluate the proposed clinical differences. The results differentiated these dementia syndromes, and the pattern of performance was consistent with the cortical-subcortical hypothesis.     

Neuropsychological prediction of dementia in Parkinson's disease

OBJECTIVE—To identify neuropsychologicalcharacteristics predictive of later dementia in Parkinson's disease.
METHODS—A comprehensive neuropsychological testbattery was administered to a cohort of 89 initially non-dementedpatients with Parkinson's disease consecutively enrolled at aspecialised Parkinson's disease clinic. They were reassessed after amean of 3.5 years for the diagnosis of dementia. The Coxproportional hazards model was used to identify baselinecharacteristics predictive of dementia.
RESULTS—Only four of the baseline clinicalcharacteristics of Parkinson's disease and neuropsychologicalvariables remained independently linked to subsequent development ofdementia: the age of onset of Parkinson's disease (>60 years;relative risk (RR) 4.1, 95% confidence interval (95% CI) 1.8-24.0,p<0.03), the picture completion subtest of the Wechsler adultintelligence scale (score<10; RR 4.9, 95% CI 1.0-24.1, p<0.02), theinterference section of the Stroop test (score<21; RR 3.8, p=0.08),and a verbal fluency task (score<9; RR 2.7, 95% CI 0.8-9.1, p=0.09).Depressive symptoms and the severity of motor impairment were notpredictive of dementia.
CONCLUSION—These features are different from theneuropsychological characteristics predictive of Alzheimer's dementiain healthy elderly people (mainly memory and language performance).They are in keeping with the well known specificity of the impairmentsin Parkinson's disease for visuospatial abilities and difficulties ininhibiting irrelevant stimuli. It is postulated that the compositenature of the picture completion subtest, involving several cognitive abilities impaired in Parkinson's disease, explains its sensitivity.

     

Neuropsychological profile of dementia with Lewy bodies

Dementia with Lewy bodies (DLB) accounts for 10–25% of all dementia cases in clinical populations and is considered to be the second most common degenerative dementia in elderly people after Alzheimer's disease (AD). Dementia with Lewy bodies is characterized by the presence of cognitive, psychiatric, and motor symptoms. Although the neuropsychological profiles of patients with DLB often differ from those of patients with AD, the diagnostic sensitivity, specificity, and predictive values of these profiles remain largely unknown. The present paper reviews the neuropsychological profiling of DLB and attempts the neuropsychological differentiation of DLB from AD.     

Neuropsychological profiles of persons with mental retardation and dementia

This study examined the use of neuropsychological tests to assist in the differential diagnosis of dementia among persons with mental retardation. The author compared performances of persons with mental retardation and dementia (n = 10) to persons with mental retardation without dementia (n = 12). Participants were matched by IQ (mild or moderate mental retardation), age, presence of Down syndrome, and gender. In addition, all participants in the dementia group had corroborative medical tests (i.e., imaging, EEG, or high tau low AB42 protein testing) consistent with diagnosis of dementia. Test performance was compared on measures of attention and executive functions, language, memory and learning, and a dementia screening. Results from MANOVAs and nonparametric tests revealed significantly lower performance for persons with mental retardation and dementia in all areas assessed. Cut-off scores were also developed for the sample in order to maximize sensitivity and specificity for the test battery. Despite the small sample size, these findings suggest that there are significant measurable differences in several neurocognitive domains between the two groups.     

Screening for dementia by memory testing

Enhanced cued recall provides a simple and clinically useful memory test for identifying dementia in the elderly. Because this test induces semantic processing and coordinates encoding and retrieval for maximum recall, genuine memory deficits due to impairment of specific memory processes can be distinguished from apparent memory deficits due to use of inefficient strategies or impairment of other cognitive processes. Since genuine memory deficits in the elderly are usually associated with dementia, their identification is highly predictive of clinical dementia. The present study validates the use of enhanced cued recall as a screening test for dementia in 70 aged subjects. All but one person with a pure amnesia were correctly classified. Enhanced cued recall correctly classified 97% of the 120 subjects in this and the previous study. Enhanced cued recall shows learning not revealed by free recall, providing more accurate measurement of memory, and distinguishes demented from nondemented elderly more accurately than either free recall or recognition.