assessing the handwriting process in healthy elderly persons using a computerized system

Key words: Computerized, elderly, handwriting, kinematic measures.Correspondence: S. Rosenblum, PhD, Department of Occupational Therapy, University of Haifa, Haifa 31905, Israel.E-mail: [email protected] May 15, 2005; accepted in revised form November 16, 2005.

Aging Clin Exp Res, Vol. 18, No. 5 433

ABSTRACT. Background and aims: Despite the im-portance of handwriting in everyday life, virtually no lit-erature can be found documenting the extent and rangeof everyday handwriting performance and ability amonghealthy elderly persons. The aim of this pilot studywas to examine the kinematic characteristics of thehandwriting process of healthy elderly persons and itscorrelates. Methods: Fifty-three healthy participants(aged 60 to 94) living in the community, performedfive functional writing tasks using a computerized systemwhich documented the handwriting process. Results: Inair time (i.e., the time of non-writing while writing) ac-counted for approximately half to two-thirds of total writ-ing time. Higher age was consistently associated withlonger on paper and in air time, as well as with lowerspeed and lower pressure. Conclusions: The results ofthis pilot study indicate that kinematic analysis of hand-writing provides important information about the hand-writing process among elderly people. (Aging Clin Exp Res 2006; 18: 433-439)©2006, Editrice Kurtis

INTRODUCTIONThe population aged 65 years and older is increasing

more rapidly than any other age group. The U.S. Inter-national database (1) projected that this segment of the pop-ulation will increase from 12.4% of the total U.S. popula-tion in the year 2000 to 19.6% by 2030. To prepare forthe increased demands of this population and to understandhow to provide the most appropriate and effective care forthe elderly, it is necessary to examine and comprehend thefunctional changes that accompany the aging process (2).

One functional area that significantly affects the abilityto perform everyday tasks effectively is hand function (3-5). With increasing age, hand function deteriorates as a re-sult of several underlying factors. These include behavioralfactors, such as reduced physical activity and sedentary life-styles (6, 7) as well as reduced neuromuscular function re-

Assessing the handwriting process in healthy elderlypersons using a computerized systemSara Rosenblum1 and Perla Werner2

1Department of Occupational Therapy, 2Department of Gerontology, Faculty of Social Welfare and HealthStudies, University of Haifa, Israel

lated to hand strength, speed and coordination (2, 8, 9). Ithas been suggested that the most significant musculo-skeletal factors that contribute to the difficulties that olderadults experience in the performance of activities of dailyliving were those related to their reduced ability to grip andmanipulate objects (10, 11).

Several studies have reported reduced performancespeed and capacity of healthy older people in specificcomponents of cognitive and psychomotor performancesuch as reaction time and digit symbol substitution (12,13). But there is no sufficient information available onhand function, considering its importance for older peo-ple in their everyday performance (4, 5, 14).

One of the most common daily activities performed byadults in a variety of leisure and professional settings iswriting (15). Handwriting is a complex human activity, in-volving an intricate blend of cognitive, kinesthetic and per-ceptual-motor components (16), including visual andkinesthetic perception, motor planning, eye-hand coor-dination, visual-motor integration, dexterity, and manualskills (17). Handwriting requires gripping and manipulat-ing an object, and dexterity abilities, which have been re-ported to decline in the elderly (4).

Despite the importance of handwriting in everyday life,virtually no literature can be found that documents the ex-tent and range of everyday handwriting performanceand ability among the healthy elderly. Even in studies thathave examined self-reported activities in older adults,handwriting and writing in general have been largely ne-glected (15). Moreover, although handwriting tasks are themedium through which performance is measured in stan-dardized cognitive tests, such as the digit symbol task fromthe Wechsler Intelligence Scale (18), it is mainly speed ofperformance that is emphasized, while other importantperformance aspects which may be more relevant toage-related changes are not sufficiently considered (15).

To the best of our knowledge, only two studies haveexamined the relationship between handwriting and aging

Aging Clinical and Experimental Research

in healthy elderly persons. In the first study, Dixon et al.(15) compared the handwriting speed of older adults(mean age=69.3 years) to that of younger adults (meanage=20.6) and found that older adults performed both fa-miliar and unfamiliar handwriting tasks 60% to 78%slower than the younger adults. Moreover, age-related dif-ferences in handwriting speed varied as a function ofthe familiarity of the task.

The second study (19) examined elderly persons’handwriting by asking participants to perform back andforth strokes in different directions using a digitizingtablet and a specialized pen. Results showed that themovement production of the elderly was impaired in thespatial coordination of finger and wrist movements ratherthan in acceleration (or force) control.

Despite their importance, these studies are limited bytheir methodology. Both studies used relatively smallgroups (20 and 11 participants respectively), with a largeage discrepancy between the younger group (19-26 and19-31 years) and the older one (59-89 and 63-78 years).Therefore, the question arises as to whether age-relateddifferences in performance would be found within awider group with a smaller age range (60-90). Contreras-Vidal et al. (19) also used a computerized system to obtainkinematic measures of handwriting, but asked partici-pants to perform back and forth handwriting movementsand not functional handwriting tasks. Lastly, the hand-writing process was not similar to the way people usual-ly write; a non-inking pen was used, and the trajectory ofthe pen was visible in real-time on the display but not onthe paper. In contrast, Dixon et al. (15) asked participantsto perform functional handwriting tasks but their mainmeasure was handwriting speed measured with a stop-watch, because they did not use a computerized systemwhich would have enabled them to obtain richer spatial,temporal and pressure data.

The aim of the current pilot study was to investigate thespatial, temporal, and pressure measures of handwritingamong healthy elderly individuals during real-time per-formance of functional everyday handwriting tasks.

METHODSParticipantsParticipants included 53 healthy and independently

functioning elderly persons living in the community, re-cruited from several day care centers in northern Israel

Inclusion criteria were: Living in Israel for at least 20years; right-handedness and normal or corrected to nor-mal vision and hearing ability.

Exclusion criteria were: Participants were requestedto report whether they do or do not suffer from a neu-rological disease, arthritis or hypothyroidism, based on astructured checklist. Those who reported having any oneof these diagnoses were excluded from the study. Personstaking medications affecting the central nervous system

were requested to refrain from taking their medication onthe day of the test and on the preceding day.

Cognitive status: All participants were administeredthe Hebrew version of the Mini-Mental State Examination(MMSE) (20), an 11-item instrument assessing cognitivefunctioning, with scores ranging from 0 (total cognitive de-terioration) to 30 (normal cognitive functioning). Accordingwith the reported cut-off score in the literature (21, 22), par-ticipants scoring less than 24 were excluded from the study.

Equipment and TasksDigitizing Tablet and On-line Data Collection and

Analysis Software: A suite of on-line, computerizedhandwriting evaluation (POET-Penmanship ObjectiveEvaluation Tool, 23, 24) was used to administer thestimuli and to collect and analyze the data. The POET wasdeveloped in response to the absence of a quantitative ob-jective handwriting evaluation for the Hebrew language,but is currently suitable for use with all languages.

The tool includes two main parts: 1) data collection,which is language-independent and easy to use for hand-writing tasks, and 2) data analysis, which was pro-grammed via MATLAB software toolkits. The data col-lection part was designed to be as user-friendly as possi-ble, so as to enable clinicians and researchers to employit in their everyday practice.

The study described in this paper focused on writingtasks written in the Hebrew language. Hebrew differs inseveral key ways from Latin-based scripts, as shown in Fig-ure 1, in which all the 22 letters of the Hebrew alphabetare graphically represented. Hebrew writing progressesfrom right to left, successive letters are not connectedeven during script (cursive) writing, and five letters differ intheir form when they are written at the end of a word. Asin other languages, some letters in the Hebrew alphabetare constructed from two separate, unconnected compo-nents. For example, as demonstrated in Figure 1, “Aleph”,the first letter on the right, is formed by combining two sep-arate components, as are the fifth, ninth and tenth letters.

All writing tasks were performed on A4 lined paper affixedto the surface of a WACOM Intuos 2 (model GD 0912-12X18) x-y digitizing tablet using a wireless electronic inkingpen (Model GP-110). Displacement, pressure and pen tip an-gle were sampled at 100 Hz via a 1300 MHz Pentium (R) Mlaptop computer. The computerized system enables thecollection of spatial, temporal and pressure data while thesubject is writing (Fig. 1). The digitizer gives an accurate tem-poral measure along the total writing performance, bothwhen the pen is touching the tablet and when it is in the air.Regarding the spatial measure, the digitizer gives an accuratemeasure when the pen is touching the tablet and/or whenit is lifted up to 6 mm above the digitizer. Beyond 6 mm, thespatial measurement is not reliable. Therefore, in the currentstudy, total measures are not reported.

Tasks: Participants were requested to perform 8 func-

S. Rosenblum and P. Werner

434 Aging Clin Exp Res, Vol. 18, No. 5

Aging Clin Exp Res 18: 433-439, 2006©2006, Editrice Kurtis

tional writing tasks: five non-memory related tasks andthree memory-related tasks. Non-memory related tasks in-cluded: copying a phone number, copying a grocery list(five words), copying the details of a check into the ap-propriate places, copying the alphabet sequence, andcopying a paragraph (107 characters). Memory-relatedtasks included writing a phone number read to the par-ticipants, a grocery list read to them, and writing the al-phabet sequence from memory. All tests were performedin Hebrew. Two underlying assumptions guided task se-lection. First, they are functional tasks related to theperformance of daily activities. Second, they reflect an in-crease in difficulty, as they are longer and involve (also inthe Hebrew alphabet) an increased need for cognitive andmotor abilities.

Kinematic measures: Primary kinematic measures in-cluded temporal, spatial and pressure measures of hand-writing. Temporal measures included the time taken to com-plete the writing tasks measured in seconds and includingon paper time, in air time (i.e., the time during the writingof the task when the pen was not in contact with thewriting surface - meaning when the pressure was under 50in non-scaled pressure units). The in air time included all thetime of non-writing while completing the tasks. Velocity wasalso calculated as a mean for the whole task.

Spatial measures included the on paper path length ofall characters written and measured in millimeters, i.e., themean distance from starting point to finishing point ineach written letter. The pressure measure included themean pressure implemented on the writing surface in non-scaled units from 0-1026.

Background characteristicsSocio-demographic characteristics: These included

gender, age, and number of years of education.Subjective memory complaints: Participants were

administered the Subjective Memory Scale (25). The

scale uses 6 questions to assess memory difficulties ex-perienced by participants. Each item was rated from 0 (notat all) to 2 (all the time). A composite index of the sum ofthe 6 items was created.

ProcedureAll participants were examined in similar environ-

mental conditions in a quiet room, at their homes or at theday care center. After the aim of the study had been ex-plained, participants were administered the MMSE and thedemographic questionnaire, in order to determine whetherthey were suitable for participation in the study accordingto the stated inclusion and exclusion criteria. Next, thoseeligible for participation performed the experimentaltasks. The handwriting tasks were presented on a com-puter screen, after which the three memory tasks wereperformed. The testing procedure took approximately 15minutes. Participants were also asked about their hand-writing habits.

Ethical considerations: The present study was partof a larger study assessing the kinematic characteristicsof elderly persons with mild cognitive impairment,mild Alzheimer’s disease, and healthy controls (26). Theprocedure of the study was approved by the Helsinkicommittee of the hospital participating in the largestudy.

RESULTSDescription of sampleAs Table 1 shows, most participants were women, and

married. Their mean age was 73, with a range from 60to 94. They had relatively high education and their meanMMSE score was 28.6 (SD=1.1); 46 out of 53 subjectsachieved final scores between 27-30, and the other 8 sub-jects final scores between 24-26. Participants reported rel-atively low subjective memory problems (mean=3.2;SD=2.3).

Assessing the handwriting process in healthy elderly persons



Fig. 1 - An example of on paper (thick lines) and in air measures (thin lines) among a 68-year-old person (1A) and a 94-year-old person(1B) while performing the non-memory-related alphabet task.

1A

1B

Handwriting behaviorAlmost all participants (96.2%) reported writing in He-

brew, and writing every day or almost every day (94.3%).

Characteristics of kinematic handwriting measures across different tasks:

Table 2 lists the means and standard deviations ofthe handwriting measures in the different tasks. As ex-pected, times on paper and in air increased with thelength of the task. In air time accounted for approximatelyhalf to two-thirds of total writing time. The highest in airtime was recorded in copying the alphabet (64.4% of to-tal time) and writing the details of a check (63.4% of to-tal time), and the lowest in air time was recorded for copy-ing a phone number and a grocery list (50.6% and49.2%). Lastly, on paper and in air times were statisticallylonger for writing a grocery list and the alphabet frommemory, than for simple copying. An example of on pa-per and in air measures is shown in Figure 1.

Mean velocity and pressure remained relatively stableacross tasks.

Correlates of handwriting measuresBecause Kolgomorov-Smirnov tests had shown that

kinematic measures were normally distributed (p>0.05),Pearson correlations were used to assess the relationshipsbetween these measures and the following variables:

participants’ age, gender, educational level, and cognitivestatus. Given the variety and multiplicity of the tasks ex-amined, only relationships that were statistically significantin all or almost all four tasks are reported.

As shown in Table 3, higher age was consistently as-sociated with longer on paper and in air times (correlationsranging from r=0.44 to 0.49, p<0.01; and 0.30 to0.58, p<0.01, respectively), as well as with lower speed(-0.33 to -0.40, p<0.05) and – with the exception copy-ing a phone number and writing it from memory, andcopying the alphabet - also with lower pressure (-0.30 to-0.33, p<0.05). Higher education was consistently as-sociated with higher pressure (r=0.47 to 0.59, p<0.001).Gender and cognitive status were not significantly asso-ciated with any of the kinematic measures.

DISCUSSIONThe current study represents one step in addressing the

challenges of an increasingly aging population. Resultscontribute to knowledge about the effects of normal agingon handwriting, which is one manifestation of hand func-tion (4, 14). It also assesses objective measures of func-tional performance, since many previous studies on func-tional decline among the elderly have been based onself-reports of disability (27, 28). Self-report assessmentsmay be limited, based on previous evidence that olderadults often underreport their disabilities or minimizethe extent of their limitations (29).

Despite advances in technology, most participantsstated that they performed handwriting tasks every day oralmost every day, which means that handwriting is still ameaningful and useful activity for the elderly (15). How-ever, although they were based on participants’ subjectivereports, the majority reporting that they had no difficultyin performing writing tasks, the results of our objectivemeasures of handwriting indicated a decrease in writingspeed and pressure and an increase in writing time withincreasing age. Future longitudinal studies should exam-ine whether elderly persons are aware of the decrease in




Table 2 - Mean (SD) of kinematic measures among different writing tasks.

Writing a Writing a Writing the Writing a Writing a phone number grocery list alphabet paragraph check

From Copying From Copying From Copyingmemory memory memory

On paper time 4.2 (1.1) 4.0 (2.0) 7.2 (1.8)** 6.7 (1.4) 6.9 (1.9)** 6.4 (1.6) 30.3 (7.2) 14.9 (4.6)In air time 4.3 (2.3) 6.4 (9.4) 7.9 (3.5)*** 6.5 (3.3) 12.5 (8.2)*** 11.2 (7.4) 48.8 (24.7) 25.8 (14.5)On paper length 99.7 (23.1) 97.4 (36.9) 217.2 (54.2) 213.6 (69.3) 193.6 (43.2) 188.5 (46.6) 893.2 (198.2) 385.5 (84.0)Velocity 32.2 (8.1) 32.9 (9.9) 37.5 (8.6) 38.1 (9.7) 37.3 (8.5) 37.6 (9.6) 38.5 (8.4) 35.8 (7.8)Pressure 772.1 (174.1) 714.8 (214.8) 756.1 (176.1) 704.4 (217.6) 787.7 (160.8) 721.9 (205.4) 770.6 (172.0) 783.6 (159.5)

***Differences between memory and non-memory related tasks at p<0.01. **Differences between memory and non-memory related tasks at p<0.05. Timedata in seconds; length data in millimeters.

Table 1 - Socio-demographic characteristics of participants (n=53).

Characteristics

Mean age (SD) 72.7 (8.1)% female 54.7Marital Status

Married 81.1Widowed 18.9

Mean years of education (SD) 14.2 (3.0)

their handwriting efficiency and whether the decrease inboth handwriting speed and pressure are a manifestationof a decrease in their ability to perform activities of dailyliving (7, 30).

The results of the current study supply objective tem-poral and spatial measures of functional handwritingperformance. In the temporal domain, the results sub-stantiate data in the literature showing that performancetime increases while speed of performance decreaseswith age in various hand tasks (2, 5, 15, 31-33). In-deed, other studies found slowness among the elderly bothin movement preparation and execution (33), reactiontime (31) and total speed of hand performance (2, 5).

Higher age was also found to be consistently associat-ed with lower pressure. The pressure applied to the writ-ing surface while grasping the pen may be a functional

measure of hand strength (29). The results of our study aresimilar to those of previous studies that found handstrength to decrease with age (2, 5, 34-37). More specif-ically, Ranganathan et al. (7) found that there is a signifi-cant decline in the hand strength components required forhandwriting, i.e., finger-pinch strength and steady precisionfinger pinch posture. In fact, the current study presents ob-jective measures for slow handwriting speed as well as de-creased hand strength as applied to the writing surface.

Some authors have linked slowness in the elderly withdecline in hand strength. Experimental data suggest thatmovement slowness is related to reduced capability to ini-tiate, control and modulate force (38-42). This suggeststhat movements requiring small levels of force, like hand-writing, should be impaired in the elderly (19). Therefore,the objective measure of the pressure applied to thewriting surface may be a manifestation of an age-relatedprocess affecting hand function, and may influence ev-eryday function and quality of life for the people affected.This result is important in view of Gilberston and Barber-Lomax’s (30) finding that a decline in hand grip strengthhas been shown to predict the risk of future disability inpeople aged 77 years and older.

Several explanations have been suggested for in-creased performance time and decreased performancespeed and hand strength with age. Explanations maybe divided into three main categories: those focusing onthe brain and neurological mechanisms, e.g., neurologi-cal integrity, or decrease in the number of motor units (14,32, 43); those focusing more specifically on sensory-motor mechanisms, e.g., more time being required to pro-cess incoming sensory data, or impaired tactile infor-mation (31, 44, 45); and those relying on other physio-logical processes that influence performance time andhand strength, e.g., hormonal influences or loss of bonemass (14, 40). The results of our study cannot determinewhich of these explanations is the most accurate, becauseit focused on the functional manifestations of aging. Fur-ther basic research is needed to understand the relation-ships between the functional outcomes described here andtheir possible causes.

An unexpected finding in this study was that higher ed-ucation was consistently associated with higher pres-sure. One explanation is that higher education is corre-lated with elderly people’s awareness of the importanceof hand activation and its effect on the strength andfunctional abilities of their hands. Future studies would berequired in order to examine this relationship.

This study carried out temporal measures of in airtime, in addition to those described in previous studies (i.e.,total time, or speed of performance). The highest per-centage of in air time out of total time was recorded inwriting the alphabet from memory and in writing thedetails of a check. Since in air time reflects the timespent not writing while writing, we hypothesize that fre-




Table 3 - Pearson correlations between age and on paper and inair times.

Writing task and kinematic measure Age

Writing a phone number - from memoryOn paper time 0.45***In air time 0.26Mean speed -0.37**Mean pressure -0.23Writing a phone number - copyingOn paper time 0.49***In air time 0.30*Mean speed -0.33*Mean pressure -0.16Writing a grocery list - from memory On paper time 0.43**In air time 0.39**Mean speed -0.40**Mean pressure -0.30*Writing a grocery list - copying On paper time 0.49***In air time 0.48***Mean speed -0.33*Mean pressure -0.30*Writing the alphabet - from memoryOn paper time 0.44**In air time 0.38**Mean speed -0.37**Mean pressure -0.30*Writing the alphabet - copyingOn paper time 0.48***In air time 0.39**Mean speed -0.36**Mean pressure -0.22Writing a paragraphOn paper time 0.49***In air time 0.58***Mean speed -0.35*Mean pressure -0.33*Writing a checkOn paper time 0.47***In air time 0.50***Mean speed -0.34*Mean pressure -0.30*

***p<0.001, **p<0.01, *p<0.05

quency of performance and familiarity with the task affectthe duration of in air time. These results are similar tothose of Dixon et al. (15), who found that more difficultand unfamiliar tasks were performed more slowly thanmore familiar tasks by both younger and older adults. Eventhe alphabet task is not frequently performed and is not al-ways familiar to the elderly. Moreover, in order to performit, participants need to have a visual image of the spatialfeatures of the letter forms (46, 47). As for check writing,one may assume that it is a more familiar task, but onethat requires subjects to consider spatial cues (where towrite the numbers and letters, where to sign, and soon). Since Contreas-Vidal et al. (19) found that elderly per-sons are impaired in the spatial coordination of finger andwrist movements, it seems that the spatial requirements ofthe check and alphabet tasks and the unfamiliarity ofthe alphabet task influenced the amount of in air time re-quired to perform these tasks.

The finding that cognitive status was not significantly as-sociated with any of the kinematic measures seems to belimited by the distribution of the cognitive status scores (45out of 53 subjects achieved final scores ranging from 27 to30 on the MMSE). In a previous study (23), the in airmeasure was a sensitive differentiator between children withpoor and those with proficient handwriting. Indeed, in astudy on handwriting among three groups of elderly people(with mild cognitive impairment, mild Alzheimer’s disease,and healthy persons), the in air time was found to be an im-portant differentiator between the three groups (26).

As in most previous studies (2, 5, 48), gender was notsignificantly associated with any of the kinematic mea-sures. It seems that although, with age, women tend tolose more bone density than men, they preserve bettermuscle quality than men (48).

The percentage of decrease in strength due to age issimilar for men and women, regardless of their life-style(5). These findings contradict those of Raganathan etal. (7), who found that, with age, women experiencegreater decline in dexterity and strength than do men.

The findings of this pilot study indicate that using acomputerized system is not only feasible but may also pro-vide a viable way of performing clinical evaluations whilereducing the anxiety accompanying patients in test situ-ations (49). Another advantage of the system is that,unlike many handwriting evaluations which are basedon evaluation of the writing product – see (50) for moredetails –, this system provides objective temporal, spatialand pressure measures of the handwriting process whileparticipants are performing a functional handwriting taskin their natural environment.

There are several limitations to this study. First, the useof a relatively small sample does not allow us to general-ize. Future studies using larger and more representativesamples, including participants who write in languagesother than Hebrew, as well as younger comparison

groups are required, especially in order to examine rela-tionships with age more carefully. Second, as alreadymentioned, pressure was measured in non-scaled units. Amore accurate measure needs to be developed in order tostudy age influences on pressure during handwriting per-formance. Lastly, given the preliminary and descriptivecharacter of this pilot study, no multivariate analyseswere performed. Future studies, using larger and morerepresentative samples should disentangle the relationshipsof the different variables examined.

Notwithstanding these limitations, we consider thepresent study as the first attempt to examine the hand-writing process of healthy elderly persons objectively.Research in this area should be expanded, in order to un-derstand this important process in the daily life of elder-ly persons.

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assessing the handwriting process in healthy elderly persons using a computerized system

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