Ideomotor apraxia in early Alzheimer's disease: time and accuracy measures

Investigating the associations between upper limb motor function and cognitive impairment: a scoping review

Upper limb motor function is a potential new biomarker of cognitive impairment and may aid discrimination from healthy ageing. However, it remains unclear which assessments to use. This study aimed to explore what methods have been used and to describe associations between upper limb function and cognitive impairment. A scoping review was conducted using PubMed, CINAHL and Web of Science. A systematic search was undertaken, including synonyms for key concepts 'upper limb', 'motor function' and 'cognitive impairment'. Selection criteria included tests of upper limb motor function and impaired cognition in adults. Analysis was by narrative synthesis. Sixty papers published between 1998 and 2022, comprising 41,800 participants, were included. The most common assessment tasks were finger tapping, Purdue Pegboard Test and functional tasks such as writing. Protocols were diverse in terms of equipment used and recording duration. Most participants were recruited from clinical settings. Alzheimer's Disease was the most common cause of cognitive impairment. Results were mixed but, generally, slower speed, more errors, and greater variability in upper limb movement variables was associated with cognitive impairment. This review maps the upper limb motor function assessments used and summarises the available evidence on how these associate with cognitive impairment. It identifies research gaps and may help guide protocols for future research. There is potential for upper limb motor function to be used in assessments of cognitive impairment.

Bimanual Gesture Imitation in Alzheimer's Disease

BACKGROUND/OBJECTIVE

Unimanual gesture production or imitation has often been studied in Alzheimer's disease (AD) during apraxia testing. In the present study, it was hypothesized that bimanual motor tasks may be a sensitive method to detect impairments of motor cognition in AD due to increased demands on the cognitive system.

METHODS

We investigated bimanual, meaningless gesture imitation in 45 AD outpatients, 38 subjects with mild cognitive impairment (MCI), and 50 normal controls (NC) attending a memory clinic. Participants performed neuropsychological background testing and three tasks: the Interlocking Finger Test (ILF), Imitation of Alternating Hand Movements (AHM), and Bimanual Rhythm Tapping (BRT).

RESULTS

The tasks were short and easy to administer. Inter-rater reliability was high across all three tests. AD patients performed significantly poorer than NC and MCI participants; a deficit to imitate bimanual gestures was rarely found in MCI and NC participants. Sensitivity to detect AD ranged from 0.5 and 0.7, specificity beyond 0.9. ROC analyses revealed good diagnostic accuracy (0.77 to 0.92). Impairment to imitate bimanual gestures was mainly predicted by diagnosis and disease severity.

CONCLUSION

Our findings suggest that an impairment to imitate bimanual, meaningless gestures is a valid disease marker of mild to moderate AD and can easily be assessed in memory clinic settings. Based on our preliminary findings, it appears to be a separate impairment which can be distinguished from other cognitive deficits.

Limb apraxia in neurodegenerative disorders

SUMMARY Apraxia is a cognitive-motor disorder affecting gestural communication and tool use, and is seen in various neurodegenerative disorders. Apraxia is a major feature of the corticobasal syndrome associated with nonlevodopa-responsive, typically asymmetric parkinsonism. Mild apraxia may also be seen in Parkinson’s disease, at least in later stages of the disease. Furthermore, patients with Alzheimer’s disease or posterior cortical atrophy are prone to develop apraxia during their disease course. However, apraxia may be difficult to dissect from other motor (e.g., dystonia and bradykinesia in corticobasal syndrome) or cognitive (e.g., dysexecutive or semantic memory deficits in Alzheimer’s disease) dysfunction. Therefore, the ecological significance of apraxia in neurodegenerative disorders may not always be obvious. Although treatment protocols for apraxia have been developed in stroke, there is little information on the management of apraxia in neurodegenerative disorders. Owing to their progressive nature, benefits from therapeutic interventions are certainly limited, although some capacity of motor learning may be preserved, at least in earlier disease stages. In advanced cases, management of apraxia should focus on compensatory measures, for instance, on adapting the patient’s environment to their needs, particularly when related to safety and comfort.

A brief computerized self-screen for dementia

Among his many contributions to the field of neuropsychology, Arthur Benton recognized the broad public health significance and unique ability of focused neuropsychological tests to screen for dementia. The need for validated screening tests for the presence of dementia will continue to grow as the cumulative prevalence of dementia grows and as our ability to treat or slow the progression of these diseases improves. We have developed a brief, self-administered computerized screening test for dementia, which is user friendly to the majority of elderly participants, including those with dementia. This test demonstrates comparable discriminant validity to the Mini Mental State Examination (MMSE), and its subscales correlate well with the traditional neuropsychological tests upon which it is based. We discuss its relative merits and limitations in comparison to other current instruments as well as suggesting future directions for this field.

Ideational action impairments in Alzheimer’s disease

We report data from a group of patients with mild Alzheimer's disease on a range of tasks requiring either stored semantic knowledge about objects (e.g., naming object use) or the execution of action to objects (e.g., miming and using objects). We found that the patients were impaired at miming in response to objects, even when they could describe the object's function. On the other hand, copying gestures was not impaired relative to naming gestures, indicating that an ideomotor deficit in action execution, per se, was unlikely to explain the impairments in object use. We suggest instead that the patients had an impairment in stored motor programmes for action, over and above their deficits in semantic knowledge. Despite this, the patients were better at using than at miming to objects, consistent with the view that proprioceptive input (when using objects) can directly constrain selection of the appropriate motor programme for action.

Cube drawing performances in normal ageing and Alzheimer's disease: data from the PAQUID elderly population-based cohort

To assess the influence of age and other sociodemographical variables, depressive symptomatology and the occurrence of Alzheimer's disease (AD) on cube drawing, we examined the performance of 858 normal subjects and 17 incident AD patients in the PAQUID population-based study. Cube drawing was first performed on verbal command and, in case of failure, a model of a cube was given to the subjects to copy. Normal subjects had some difficulties in drawing a cube on verbal command, evidenced by 40% failure in the drawing-to-command condition, while only 17% still failed in the drawing-to-copy condition. Multivariate logistic regressions showed that age, gender, and educational level were associated with cube drawing failure in both conditions, but depressive symptomatology was only associated with persistent failure in the drawing-to-copy condition. Seventy-six point five percent of incident AD subjects failed in the drawing-to-command condition and 64.7% did not benefit from the presentation of the model. Analysis showed that persistent failure in the copy condition was the best level of differentiation between normal and AD subjects.

Pantomime and imitation of limb gestures in relation to the severity of Alzheimer's disease

The present study was designed to investigate the relationship between performance of limb gestures and the severity of Alzheimer's disease (A.D.). Apraxia tends to occur at later stages of A.D., and the severity of apraxia has been shown to vary with the severity of A.D. dementia. Participants were 19 mild (including 9 with no cognitive impairment and 10 with mild impairment) and 18 moderate A.D. patients as well as 25 controls and they were asked to pantomime (P) or imitate (both concurrent (CI) and delayed (DI)), eight transitive gestures to assess praxis performance. Results indicated that the moderate patients performed less accurately than mild and non-impaired patients, and that across all groups, the imitation conditions were performed less accurately than pantomime, relative to controls. Correlational analyses revealed that MMSE scores were correlated with all three performance conditions suggesting that impaired praxis performance may relate to more global impairment. Finally, a frequency analysis was conducted to examine whether A.D. patients showed patterns of apraxia as described in Roy's model (1996). Results indicated that A.D. patients showed greatest impairment on pattern 7 (deficits in P, DI, and CI), reflecting late-stage gesture production, with a greater frequency of moderate patients exhibiting each apraxic pattern.

Effects on memory of verbal labeling for hand movements in persons with Alzheimer's disease

This study examined 1) whether patients diagnosed with dementia of the Alzheimer type spontaneously form verbal labels to remember nonmeaningful sequences of hand movements, 2) whether an instruction for a verbal labeling (VL) strategy could enhance memory performance, and 3) whether a relationship exists between the memory span for hand movements and a score on the Mini-Mental State Examination (MMSE). Of 18 Alzheimer's patients, 16 did not use the VL strategy spontaneously. However, if instructed, 12 of these 16 were able to use the technique. Of these 12, four were able to retain the strategy. There was a significant correlation only between the movement memory span and the MMSE. Meta-memory of VL seems independent of visuospatial memory and cognitive status.

Apraxic disturbances in patients with mild to moderate Alzheimer's disease

Twenty-two patients meeting the NINCDS-ADRDA diagnostic criteria for probable AD were included in the study, along with 10 matched controls. Praxic disturbances were investigated using eight tasks and the results were interpreted according to the neuropsychological model of Roy and Square modified by Rothi et al. (1988) [Aphasiology 21:381-388] which distinguishes a conceptual system concerned with knowledge of the action and function of gestures and a production system that effects gestures in the environment. Disturbance of the production system was found only in 17 patients. Disturbance of the production system was correlated to disturbance of verbal comprehension. The patients scored lower using the left hand than the right. Disturbance of the conceptual system was found in all patients and was not significantly correlated with other cognitive deficits. No significant difference in results was found according to the type of input to the conceptual system (visual or verbal). Deficits in tasks using real objects were correlated to disturbances of both the production and conceptual systems. Most patients performed poorly both in tasks exploring the conceptual system and in those exploring the production system. However, two patients performed badly in production tasks but had performances in the range of controls for conceptual tasks and one patient had the opposite pattern of dissociation. This provides evidence that the production and the conceptual system are independent. Impairment in the ability to perform everyday activities was correlated to disturbances of the conceptual system whereas poor performances in tasks exploring the production system or in using real objects were not.