Central and peripheral aspects of writing disorders in Alzheimer's disease

Linguistic, visuospatial, and kinematic writing characteristics in cognitively impaired patients with beta-amyloid deposition

Introduction

Beta-amyloid (Aβ) deposition, a hallmark of Alzheimer's disease (AD), begins before dementia and is an important factor in mild cognitive impairment (MCI). Aβ deposition is a recognized risk factor for various cognitive impairments and has been reported to affect motor performance as well. This study aimed to identify the linguistic, visuospatial, and kinematic characteristics evident in the writing performance of patients with cognitive impairment (CI) who exhibit Aβ deposition.

Methods

A total of 31 patients diagnosed with amnestic mild cognitive impairment (aMCI) with Aβ deposition, 26 patients with Alzheimer's-type dementia, and 33 healthy control (HC) participants without deposition were administered tasks involving dictation of 60 regular words, irregular words, and non-words consisting of 1-4 syllables. Responses from all participants were collected and analyzed through digitized writing tests and analysis tools.

Results

In terms of linguistic aspects, as cognitive decline progressed, performance in the dictation of irregular words decreased, with errors observed in substituting the target grapheme with other graphemes. The aMCI group frequently exhibited corrective aspects involving letter rewriting during the task. In terms of visuospatial aspects, the AD group displayed more errors in grapheme combination compared to the HC group. Lastly, in the kinematic aspects, both the aMCI group and the AD group exhibited slower writing speeds compared to the HC group.

Discussion

The findings suggest that individuals in the CI group exhibited lower performance in word dictation tasks than those in the HC group, and these results possibly indicate complex cognitive-language-motor deficits resulting from temporal-parietal lobe damage, particularly affecting spelling processing. These results provide valuable clinical insights into understanding linguistic-visuospatial-kinematic aspects that contribute to the early diagnosis of CI with Aβ deposition.

A study of auxiliary screening for Alzheimer’s disease based on handwriting characteristics

Background and objectives

Alzheimer’s disease (AD) has an insidious onset, the early stages are easily overlooked, and there are no reliable, rapid, and inexpensive ancillary detection methods. This study analyzes the differences in handwriting kinematic characteristics between AD patients and normal elderly people to model handwriting characteristics. The aim is to investigate whether handwriting analysis has a promising future in AD auxiliary screening or even auxiliary diagnosis and to provide a basis for developing a handwriting-based diagnostic tool.

Materials and methods

Thirty-four AD patients (15 males, 77.15 ± 1.796 years) and 45 healthy controls (20 males, 74.78 ± 2.193 years) were recruited. Participants performed four writing tasks with digital dot-matrix pens which simultaneously captured their handwriting as they wrote. The writing tasks consisted of two graphics tasks and two textual tasks. The two graphics tasks are connecting fixed dots (task 1) and copying intersecting pentagons (task 2), and the two textual tasks are dictating three words (task 3) and copying a sentence (task 4). The data were analyzed by using Student’s t-test and Mann–Whitney U test to obtain statistically significant handwriting characteristics. Moreover, seven classification algorithms, such as eXtreme Gradient Boosting (XGB) and Logistic Regression (LR) were used to build classification models. Finally, the Receiver Operating Characteristic (ROC) curve, accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Area Under Curve (AUC) were used to assess whether writing scores and kinematics parameters are diagnostic.

Results

Kinematic analysis showed statistically significant differences between the AD and controlled groups for most parameters (p < 0.05, p < 0.01). The results found that patients with AD showed slower writing speed, tremendous writing pressure, and poorer writing stability. We built statistically significant features into a classification model, among which the model built by XGB was the most effective with a maximum accuracy of 96.55%. The handwriting characteristics also achieved good diagnostic value in the ROC analysis. Task 2 had a better classification effect than task 1. ROC curve analysis showed that the best threshold value was 0.084, accuracy = 96.30%, sensitivity = 100%, specificity = 93.41%, PPV = 92.21%, NPV = 100%, and AUC = 0.991. Task 4 had a better classification effect than task 3. ROC curve analysis showed that the best threshold value was 0.597, accuracy = 96.55%, sensitivity = 94.20%, specificity = 98.37%, PPV = 97.81%, NPV = 95.63%, and AUC = 0.994.

Conclusion

This study’s results prove that handwriting characteristic analysis is promising in auxiliary AD screening or AD diagnosis.

Handwriting Changes in Alzheimer's Disease: A Systematic Review

BACKGROUND

Handwriting is a complex process involving fine motor skills, kinesthetic components, and several cognitive domains, often impaired by Alzheimer's disease (AD).

OBJECTIVE

Provide a systematic review of handwriting changes in AD, highlighting the effects on motor, visuospatial and linguistic features, and to identify new research topics.

METHODS

A search was conducted on PubMed, Scopus, and Web of Science to identify studies on AD and handwriting. The review followed PRISMA norms and analyzed 91 articles after screening and final selection.

RESULTS

Handwriting is impaired at all levels of the motor-cognitive hierarchy in AD, particularly in text, with higher preservation of signatures. Visuospatial and linguistic features were more affected. Established findings for motor features included higher variability in AD signatures, higher in-air/on-surface time ratio and longer duration in text, longer start time/reaction time, and lower fluency. There were conflicting findings for pressure and velocity in motor features, as well as size, legibility, and pen lifts in general features. For linguistic features, findings were contradictory for error patterns, as well as the association between agraphia and severity of cognitive deficits.

CONCLUSIONS

Further re-evaluation studies are needed to clarify the divergent results on motor, general, and linguistic features. There is also a lack of research on the influence of AD on signatures and the effect of AD variants on handwriting. Such research would have an impact on clinical management (e.g., for early detection and patient follow-up using handwriting tasks), or forensic examination aimed at signatory identification.

Handwriting in Alzheimer's Disease

BACKGROUND

Agraphia is a typical feature in the clinical course of Alzheimer's disease (AD).

OBJECTIVE

Assess the differences between AD and normal aging as regards kinematographic features of handwriting and elucidate writing deficits in AD.

METHODS

The study included 23 patients with AD (78.09 years/SD = 7.12; MMSE 21.39/SD = 3.61) and 34 healthy controls (75.56 years/SD = 5.85; MMSE 29.06/SD = 0.78). Both groups performed alphabetical and non-alphabetical writing tasks. The kinematographic assessment included the average number of inversions per stroke (NIV; number of peaks in the velocity profile in a single up or down stroke), percentage of automated segments, frequency (average number of strokes per second), writing pressure, and writing velocity on paper.

RESULTS

A total of 14 patients showed overt writing difficulties reflected by omissions or substitutions of letters. AD patients showed less automated movements (as measured by NIV), lower writing velocity, and lower frequency of up-and-down strokes in non-alphabetical as well as in alphabetical writing. In the patient group, Spearman correlation analysis between overt writing performance and NIV was significant. That means patients who had less errors in writing a sentence showed a higher automaticity in handwriting. The correctness of alphabetical writing and some kinematographic measures in writing non-alphabetical material reached excellent diagnostic values in ROC analyses. There was no difference in the application of pressure on the pen between patients and controls.

CONCLUSION

Writing disorders are multi-componential in AD and not strictly limited to one processing level. The slow and poorly automated execution of motor programs is not bound to alphabetical material.

Evolution of Writing Impairment in Spanish Patients with Alzheimer's Disease

BACKGROUND

Although some studies suggest that writing difficulties may be one of the early symptoms of Alzheimer's disease (AD), they have been scarcely studied compared to oral language. Particularly noteworthy is the paucity of longitudinal studies that enable the observation of writing impairment as cognitive decline progresses.

OBJECTIVE

The aim of this study was to examine the characteristics of writing in patients with AD and to monitor the deterioration of their performance over a follow-up period.

METHODS

Sixty-four participants (half with AD and half healthy elderly) were compared in a word and pseudo-word dictation task. Patients were evaluated every 6 months over a 2.5 year follow-up period.

RESULTS

The evolution of patient performance and error profile shows a typical pattern of deterioration, with early damage to the lexical pathway, which later extends to the phonological pathway and eventually affects peripheral processes.

CONCLUSION

These results confirm the presence of writing difficulties from the early stages of AD, supporting the value of this task for early diagnosis. Furthermore, it allows us to explain the contradictory data obtained in previous investigations.

Neuropsychological autopsy of testamentary capacity: Methodology and issues in the elderly

The forensic assessment of testamentary capacity is a topical issue given the prevalence of dementia illnesses and the increase in the complexity of modern financial and family structures. Although a contemporaneous assessment would be desirable, the majority of situations require a retrospective assessment of the mental state a deceased individual. Neuropsychologists, independently or as part of a board of consultants, are, therefore, frequently requested to give an expert opinion of the competence of cognitively impaired elderly testators.This paper offers a guide for carrying out a neuropsychological autopsy, namely the process of posthumous evaluation, for determining testamentary capacity. Taking into account the recent literature on the assessment of testamentary capacity, we propose a three-phase procedure for carrying out the neuropsychological autopsy in the forensic context. The neuropsychological autopsy of testamentary capacity is based on the meticulous, chronologically structured evaluation of any medical documents, available psychometric data, along with the critical examination of any source of information about the cognitive level of functioning of the deceased person at the time of the will.

Characterization of the fine motor problems in patients with cognitive dysfunction - A computerized handwriting analysis

This study proposed a new technology to assess the accuracy of Chinese handwriting by comparing every stroke movement between a template model and a handwritten script. It tested the feasibility of a computerized evaluation in the parameterization of the handwriting deterioration caused by impaired cognitive function. This study recruited 22 participants with Alzheimer's disease (AD) and 14 with amnestic mild cognitive impairment (aMCI); 18 age- and gender-matched healthy elderly individuals made up the health control. The graphomotor tasks included drawing four straight lines (vertical, horizontal, and two diagonal) as well as writing Chinese words with simple vertical, horizontal and diagonal strokes. The temporal and spatial data were calculated to measure the motor coordination. The results in geographic drawing tests reveal significant differences among the three groups in task accuracy and movement fluency, especially in nonequivalent and wrist movements. The accuracy control of the graphic drawing in the AD and aMCI groups was significantly lower than that for the subjects in the normal group. These two groups also showed longer pauses in stroke movement with the handwriting tasks. The handwriting accuracy in the AD and aMCI groups was found to be significantly different from that of the subjects in the normal group. The results of this study can be used as an indicative reference for early detection of AD or aMCI, an objective evaluation for the effectiveness of interventions, and an assessment of disease progression.

Alzheimer's Disease: Prototype of Cognitive Deterioration, Valuable Lessons to Understand Human Cognition

It is important for neurologists to become more familiar with neuropsychological evaluation for Alzheimer disease. The growth of this method in research, as an available, inexpensive, and noninvasive diagnostic approach, which can be administered even by non-specialist-trained examiners, makes this knowledge more necessary than ever. Such knowledge has a basic role in planning national programs in primary health care systems for prevention and early detection of Alzheimer disease. This is more crucial in developing countries, which have higher rates of dementia prevalence along with cardiovascular risk factors, lack of public knowledge about dementia, and limited social support. In addition compared to the neurological hard signs which are tangible and measurable, the concept of cognition seems to be more difficult for the neurologists to evaluate and for the students to understand. Dementia in general and Alzheimer's disease as the prototype of cognitive disorders specifically, play an important role to explore all domains of human cognition through its symptomatology and neuropsychological deficits.

A dynamical model improves reconstruction of handwriting from multichannel electromyographic recordings

In recent years, several assistive devices have been proposed to reconstruct arm and hand movements from electromyographic (EMG) activity. Although simple to implement and potentially useful to augment many functions, such myoelectric devices still need improvement before they become practical. Here we considered the problem of reconstruction of handwriting from multichannel EMG activity. Previously, linear regression methods (e.g., the Wiener filter) have been utilized for this purpose with some success. To improve reconstruction accuracy, we implemented the Kalman filter, which allows to fuse two information sources: the physical characteristics of handwriting and the activity of the leading hand muscles, registered by the EMG. Applying the Kalman filter, we were able to convert eight channels of EMG activity recorded from the forearm and the hand muscles into smooth reconstructions of handwritten traces. The filter operates in a causal manner and acts as a true predictor utilizing the EMGs from the past only, which makes the approach suitable for real-time operations. Our algorithm is appropriate for clinical neuroprosthetic applications and computer peripherals. Moreover, it is applicable to a broader class of tasks where predictive myoelectric control is needed.

Cognitive fluctuations in connection to dysgraphia: a comparison of Alzheimer's disease with dementia Lewy bodies

Background

The purpose of the present study was to examine the relationship between cognitive impairment and the performance of handwritten scripts presented as “letter-writing” to a close relative by patients with dementia Lewy bodies (DLB), as fluctuations of the symptoms phase, and in a matched group of patients with Alzheimer’s disease (AD). The degree of writing disability and personal, spatial, and temporal orientation was compared in these two groups.

Design and methods

Fourteen simple questions, designed in a form that could be utilized by any general practitioner in order to document the level of cognitive functioning of each patient, were presented to 30 AD patients and 26 DLB patients. The initial cognition test was designated PQ1. The patients were examined on tests of letter-writing ability. Directly after the letter-writing, the list of 14 questions presented in PQ1 was presented again in a repeated procedure that was designated PQ2. The difference between these two measures (PQ1 – PQ2) was designated DΔ. This test of letter-writing ability and cognitive performance was administered over 19 days.

Results

Several markedly strong relationships between dysgraphia and several measures of cognitive performance in AD patients and DLB patients were observed, but the deterioration of performance from PQ1 to PQ2 over all test days were markedly significant in AD patients and not significant in DLB patients. It is possible that in graphic expression even by patients diagnosed with moderate to relatively severe AD and DLB there remains some residual capacity for understanding and intention that may be expressed. Furthermore, the deterioration in performance and the differences noted in AD and DLB patients may be due to the different speed at which the process of the protein degradation occurs for functional modification of synapses.

Conclusion

Our method can be used as part of neuropsychological tests to differentiate the diagnosis between AD and DLB.

Neural correlates of spelling difficulties in Alzheimer's disease

Alzheimer's disease (AD) is associated with a general cognitive decline that affects the memory and language domains. Thus, an oral production deficit with a lexical-semantic origin has been widely observed in these patients. Their written production capacities, however, have been much less studied. We assessed the spelling abilities of 22 AD patients and a group of matched healthy controls with a test battery including written picture naming and word and pseudoword dictation tests, as well as text dictation and spontaneous writing tasks. The results of the AD patients in the discriminative tasks were then entered into voxel-based morphometry analyses along with their grey matter volumes. The patient group presented a selective impairment for word dictation, which contrasted with a spared capacity to spell pseudowords, and showed more difficulties for words with arbitrary and rule-based orthography. Moreover, they also produced less complete syntactic units in the spontaneous writing task. These results point out the lexical-semantic, as opposed to sublexical, nature of the spelling deficit associated to AD. In addition, we recognized a mainly left-lateralized cortical network, including areas in the posterior inferior temporal lobe and the superior region of the parietal cortex, which might be responsible for this impairment. Other regions, such as the putamen, were also associated to the deficit. The results of this study, hence, improve our understanding of the neuropsychological and neuroanatomical mechanisms that underlie the cognitive symptoms associated to AD.

Neural substrates for writing impairments in Japanese patients with mild Alzheimer's disease: a SPECT study

Language is fairly well preserved in most patients with mild Alzheimer's disease, but writing ability seems to be impaired even in the early stages of the disease. To investigate the neural bases of writing impairments in Alzheimer's disease (AD), we examined the correlation between writing ability and regional cerebral blood flow (rCBF) in 52 Japanese patients with mild AD compared to 22 controls, using single photon emission computed tomography (SPECT). We found that, compared with control subjects, Kana writing to dictation and copying Kanji words were preserved in AD patients, but writing to dictating Kanji words was impaired. We classified the errors in the Kanji dictation task into four types to investigate the correlation between rCBF and the error type, as follows: non-response errors, phonologically plausible errors, non-phonologically plausible errors, and peripheral errors. Non-response errors, which indicated difficulty with retrieving Kanji graphic images, were the most frequent. When controlled for confounding factors, the number of non-response errors negatively correlated with rCBF in the left inferior parietal lobule, the posterior middle and inferior temporal gyri, and the posterior middle frontal gyrus. Thus, the impaired recall of Kanji in early Alzheimer's disease is related to dysfunctional cortical activity, which appears to be predominant in the left frontal, parietal, and temporal regions.

Recognition of handwriting from electromyography

Handwriting – one of the most important developments in human culture – is also a methodological tool in several scientific disciplines, most importantly handwriting recognition methods, graphology and medical diagnostics. Previous studies have relied largely on the analyses of handwritten traces or kinematic analysis of handwriting; whereas electromyographic (EMG) signals associated with handwriting have received little attention. Here we show for the first time, a method in which EMG signals generated by hand and forearm muscles during handwriting activity are reliably translated into both algorithm-generated handwriting traces and font characters using decoding algorithms. Our results demonstrate the feasibility of recreating handwriting solely from EMG signals – the finding that can be utilized in computer peripherals and myoelectric prosthetic devices. Moreover, this approach may provide a rapid and sensitive method for diagnosing a variety of neurogenerative diseases before other symptoms become clear.

Language performance in Alzheimer's disease and mild cognitive impairment: a comparative review

Mild cognitive impairment (MCI) manifests as memory impairment in the absence of dementia and progresses to Alzheimer's disease (AD) at a rate of around 15% per annum, versus 1-2% in the general population. It thus constitutes a primary target for investigation of early markers of AD. Language deficits occur early in AD, and performance on verbal tasks is an important diagnostic criterion for both AD and MCI. We review language performance in MCI, compare these findings to those seen in AD, and identify the primary issues in understanding language performance in MCI and selecting tasks with diagnostic and prognostic value.