Equivalent spatial-rotation deficits in normal aging and Alzheimer's disease

An adaptive measure of visuospatial impairment in Dementia with Lewy Bodies

Background

Dementia with Lewy bodies (DLB) is a common cause of dementia with poor prognosis and high hospitalization rates. DLB is frequently misdiagnosed, with clinical features that overlap significantly with other diseases including Parkinson's disease (PD). Clinical instruments that discriminate and track the progression of cognitive impairment in DLB are needed.

Objectives

The current study was designed to assess the utility of a mental rotation (MR) task for assessing visuospatial impairments in early DLB.

Methods

Accuracy of 22 DLB patients, 22 PD patients and 22 age‐matched healthy controls in the MR task were compared at comparing shapes with 0°, 45° and 90° rotations.

Results

Healthy controls and PD patients performed at similar levels while the DLB group were significantly impaired. Further, impairment in the visuospatial and executive function measures correlated with MR poor outcomes.

Conclusion

These findings support the MR task as an objective measure of visuospatial impairment with the ability to adjust difficulty to suit impairments in a DLB population. This would be a useful tool within clinical trials.

Transformations of Visuospatial Images

Transformations of visuospatial mental images are important for action, navigation, and reasoning. They depend on representations in multiple spatial reference frames, implemented in the posterior parietal cortex and other brain regions. The multiple systems framework proposes that different transformations can be distinguished in terms of which spatial reference frame is updated. In an object-based transformation, the reference frame of an object moves relative to those of the observer and the environment. In a perspective transformation, the observer's egocentric reference frame moves relative to those of the environment and of salient objects. These two types of spatial reference frame updating rely on distinct neural processing resources in the parietal, occipital, and temporal cortex. They are characterized by different behavioral patterns and unique individual differences. Both object-based transformations and perspective transformations interact with posterior frontal cortical regions subserving the simulation of body movements. These interactions indicate that multiple systems coordinate to support everyday spatial problem solving.

Personal and Extrapersonal Orientation in Persons with Alzheimer Disease: Reliability and Validity of Three Assessments

This paper provides definitions of personal and extrapersonal orientation, describes assessments, and presents a study that examined the reliability and validity of these assessments for use by occupational therapists with early Alzheimer clients. Personal orientation was evaluated using the Right-left Discrimination Test and the Road-Map Test. Extrapersonal orientation was evaluated using the Map-Reading Test. These assessments were administered to 25 early Alzheimer subjects and 97 control subjects. Each of the Alzheimer subjects returned for two more visits, one for the test-retest reliability and another for the inter-rater reliability. The Road-Map Test and the Map-Reading Test met the criteria for adequate test-retest and inter-rater reliability, and intra-class correlation coefficients ranged from .71 to .96. However, the coefficients for the Right-left Discrimination test were lower (about .50). All three tests were able to discriminate between the two groups. None of the scores correlated with the Functional Spatial Abilities Questionnaire, a measure of geographic orientation. Suggestions for further research are provided.

The transfer from survey (map-like) to route representations into Virtual Reality Mazes: effect of age and cerebral lesion

BACKGROUND

To go from one place to another, we routinely generate internal representations of surrounding spaces, which can include egocentric (body-centred) and allocentric (world-centred) coordinates, combined into route and survey representations.Recent studies have shown how both egocentric and allocentric representations exist in parallel and are joined to support behaviour according to the task.Our study investigated the transfer from survey (map-like) to route representations in healthy and brain-damaged subjects. The aim was two-fold: first, to understand how this ability could change with age in a sample of healthy participants, aged from 40 to 71 years old; second, to investigate how it is affected after a brain lesion in a 8 patients' sample, with reference to specific neuropsychological frames.

METHODS

Participants were first required to perform the paper and pencil version of eight mazes, then to translate the map-like paths into egocentric routes, in order to find the right way into equivalent Virtual Reality (VR) mazes.Patients also underwent a comprehensive neuropsychological evaluation, including a specific investigation of some topographical orientation components.

RESULTS

As regards the healthy sample, we found age-related deterioration in VR task performance. While education level and gender were not found to be related to performance, global cognitive level (Mini Mental State Examination), previous experience with computer and fluidity of navigation into the VR appeared to influence VR task results.Considering the clinical sample, there was a difficulty in performing the VR Maze task; executive functions and visuo-spatial abilities deficits appeared to be more relevant for predicting patients' results.

CONCLUSIONS

Our study suggests the importance of developing tools aimed at investigating the survey to route transfer ability in both healthy elderly and clinical samples, since this skill seems high cognitive demanding and sensitive to cognitive decline.Human-computer interaction issues should be considered in employing new technologies, such as VR environments, with elderly subjects and neurological patients.

Impact of vision on the development of topographical orientation abilities

The current experiment examined the importance of visual input on the construction of inner spatial representations. Early and late-onset blind and paired control participants performed a tactile spatial orientation task. No significant group differences were observed, indicating that the blind can represent space. More errors, however, were committed by the early blind than by the late blind and sighted individuals in portions of the task that involved mental rotation skills, suggesting a potential facilitating role for vision in the proper development of spatial constructs.

Disturbed visuo-spatial orientation in the early stage of Alzheimer's dementia

A pilot study was conducted to assess previously unrecognized visuo-spatial disturbances in 45 Alzheimer's demented (AD) patients and 59 control persons all over the age of 65 years, living in the community. The results of the Clock Drawing Test (CDT) revealed high frequency (78%) of deficient performative visuo-spatial skills of mild and moderate demented AD patients. The severity of dementia was found to be a good predictor of the deficit in visuoconstructive performance. The most frequent drawing mistakes were the misplacement of numbers and clock hands, which may relate to dysfunctions of the right inferior parietal cortex. The right-left orientation (RLO) for the own body was not deteriorated in AD patients. However, significantly lower scores for RLO in the mental rotation subtest were found in mild and moderate AD groups. There were large inter-individual differences in the test scores of both demented groups. Thirty-one percent and 49% of the AD patients scored 0 points or within the normal range (more than 4 points), respectively, indicating a pseudofocal onset pattern of the dementia. The results of the CDT and Right-Left Orientation Test (RLOT) with Mental rotation showed significant positive correlation with other cognitive functions of Mini Mental State Exam, such as attention-calculation, recall and writing, and indicate that the visuo-spatial orientation (VSO) is a composite of different cognitive skills. The CDT and RLOT appears to be a useful tool for screening the elderly for disturbed VSO.

INTRAPERSONAL AND EXTRAPERSONAL SPACE: PERFORMANCE OF OLDER ADULTS ON ECOLOGICALLY VALID ORIENTATION TASKS

This experiment examined performance of 20 older adults (64 to 76 years) and 20 young adults (18 to 35 years) on two orientation tasks: The Intrapersonal task required participants to point to parts of their body corresponding to those on a line drawing; and, the Extrapersonal task involved translating a route indicated on paper to walking a route on a corresponding floor map. Older adults were found to be slower at completing both tasks, although accuracy of performance was comparable between age groups. The results were interpreted in terms of a speed-accuracy tradeoff that increases with age.

Right-left discrimination: effects of handedness and educational background

The present study investigated right left discrimination, with a paper-and-pen test with cartoon figures. The test consisted of line drawings of a person with no, one, or both arms crossing the vertical axis of the body in the figure. The subjects' task was to mark with a pencil, as fast as possible, which was the right or left hand in the figure. The line drawings were viewed from the back, from the front, or randomly alternating between the back and front views. Two studies were conducted. The first consisted of 393 adults: 153 males and 240 females; 338 right-handers and 55 left-handers. The results showed that the males performed better than the females. The left-handers and the right-handers performed equally well. However, the left-handed males performed better than the right-handed males. There was no difference in performance between the right-handed and the left-handed females. The second study consisted of 175 right-handed college students: 63 psychology students. 54 medical students, and 58 law students. The main finding was that the medical students performed better than the psychology students for all figure orientation subtests and for all arm positions. In comparison with the law students, the medical students performed at the same level on the back view subtest, but they performed better on the front view subtest and on two out of three arm positions on the alternating view subtest.

Performances of patients with a dementia of the Alzheimer type in the Standardized Road-Map test of Direction Sense

The Standardised Road-Map test of Direction Sense of money (A Standardised Road-Map Test of Direction Sense, Baltimore: Johns Hopkins University Press, 1976) was applied to a group of 14 patients diagnosed with dementia of the Alzheimer type (DAT) and to a group of 14 healthy controls matched in terms of age and education. Subjects were tested with two forms of the Money test. In the first form, the standard procedure was used. It requires patients to perform mental rotations and right or left discrimination. In the second form, the examiner turned the test sheet at each intersection to align the route with the subject. In contrast to the first condition, no mental rotation was necessary to distinguish right from left turns. This procedure has been introduced to investigate the impact of the graphic material in the map display on performance. The subjects were also given a right-left discrimination test. The results show a significant difference between DAT patients and the control group in the original form of the Money test. DAT patients also showed a deficit compared to the control subjects in the modified form of the test. The right-left discrimination test revealed no dysfunction in either group tested on problems referring to their own body parts. The designation of the body parts of somebody facing them was deficient with DAT patients. The capacity of right-left discrimination, at least with respect to parts of their own body, does not play a central role in the poor test performance of the Money test. We conclude that the Money test has a clinical value, but not specifically in the evaluation of right-left discrimination. This test should rather be viewed in terms of mental rotations and limited attention resources in DAT patients.

Cognitive screening and neuropsychological assessment in early Alzheimer's disease

Cognitive screening and detailed neuropsychological assessment provide a reliable means of detecting dementia in its earliest stages, tracking the progression of cognitive decline over time, and aiding in the differential diagnosis of various dementing disorders. In addition, recent studies have shown that mild cognitive changes, and particularly declines in memory function, are evident in the "preclinical" phase of Alzheimer's disease and may help to identify elderly individuals who are likely to develop dementia in the near future. Until effective and easily obtainable biological markers for detecting the onset and progression of Alzheimer's disease are developed, neuropsychological assessment will continue to have an important role in the dementia evaluation.

Executive control functions in degenerative dementias: a comparative review

This paper reviews the literature concerning executive control impairments in degenerative dementias. The construct of executive control functioning is examined, as is the neuroanatomy of frontal-subcortical networks, believed to underlie executive function (EF) impairments. The pattern of EF impairments in Alzheimer's disease (AD) which affects temporal and parietal brain regions most severely is contrasted with observed executive dysfunctions in patients with dementias involving degeneration of primarily frontal and frontal-subcortical brain areas. EF impairments are present in each of these types of dementing illnesses. Although EF impairments are present in AD, they are less prominent than the memory disorder in the neuropsychological profile of the disease and tend to become more pronounced later in the course of the illness. In contrast, patients with frontal or frontal-subcortical dementia may demonstrate executive dysfunction, which occurs earlier in the disease progression and may be initially more severe.

Is there a decline in picture naming with advancing age?

This review of 25 studies of the picture-naming accuracy of normal aging individuals shows that an age-related decline in picture naming is an inconsistent finding. Naming performance of older adults varied throughout the studies reviewed in this paper. This variability is attributed to the research methods used and to subject characteristics. To date, there are no studies that have considered all "nuisance factors" (e.g., health status, medication) in such a way that would allow support for a decrease in picture-naming accuracy associated with primary aging.

Performance of subjects with probable Alzheimer disease and normal elderly controls on the Gollin Incomplete Pictures Test

Our study was designed to evaluate perceptual ability measured by the Gollin Incomplete Pictures Test (in which subjects identify fragmented pictures of common objects) in Alzheimer Disease. We developed a standardized procedure for administering Gollin's test and compared the performance of 58 Alzheimer patients and 37 elderly controls on the Gollin, two design copying tests, the Mini-Mental State Examination, a verbal version of the Knox Cubes test, a recognition memory test, and a verbal fluency test. Alzheimer patients performed significantly more poorly than controls on all tests. Factor analysis demonstrated a visual perceptual factor, with loadings on the Gollin test and design copying, and three other factors representing primary memory, secondary memory, and language. Results indicate the Gollin test measures visual perceptual ability, but the precise nature of the task requires further study. Identification of fragmented pictures appears a practical and potentially useful measure for evaluating at least some aspects of visual perception in patients with generalized cognitive impairment.

A two-year longitudinal study of cognitive function in normal aging and Alzheimer's disease

A group of 136 elderly subjects were administered a comprehensive neuropsychological test battery, which was readministered 2 years later. Among the 136 elderly subjects, 86 were assigned a diagnosis of probable Alzheimer's disease. An additional 33 young subjects were administered the assessment battery at baseline only. The normal elderly group exhibited no decline in cognitive test performance over the 2-year follow-up interval. Subjects with mild cognitive impairment, however, were as likely to deteriorate between baseline and follow-up as the more severely impaired subjects. The tests that exhibited longitudinal decline in the Alzheimer's disease patients constituted a subset of the tests that revealed cross-sectional deficits relative to the normal elderly. Differences in baseline cognitive test performance and in rate of cognitive deterioration were examined in relatively young versus relatively old Alzheimer's disease patients. Potential psychometric predictors of cognitive decline in the normal elderly were identified.