Accounting for “Age” as a Variable in Aphasia Research

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http://myjms.mohe.gov.my/index.php/bsk

Artikel Ulasan/Review Article

Accounting for “Age” as a Variable in Aphasia Research: A Scoping Review

Mempertimbangkan “Umur” sebagai Pembolehubah dalam Penyelidikan Afasia: Suatu Tinjuan Skop

FATIMAH HANI HASSAN, JULIE BROWN, NABIHAH ISMAIL & AN DINH

ABSTRACT

Aphasia research often involve adults of different ages. However, researchers rarely discuss how aging processes have been accounted for in designing and reporting aphasia-related studies. The objectives of the paper are: (a) to identify trends in documenting and controlling aging effects, and (b) to discuss potential methods for accounting for aging effects in the design of aphasia research. A search on PubMed database was conducted to identify articles published between 2015 and 2020. The authors independently screened sets of article titles and abstracts. Full-text screening was conducted by the first and third author based on the inclusion criteria. Based on the review of 53 articles, all but one article reported participants’ chronological age; however, less than 50% of articles described methods for controlling potential aging effects and described application of gerontological concepts. Consideration of aging effects in reported studies was mainly related to age-related biophysiological changes. Appreciation of the complexity of aging and application of methods that also consider other types of aging effects, such as cohort and period effects may improve study design and interpretation of findings in aphasia research.

Keywords: Aphasia; older adults; aging; research; review

ABSTRAK

Penyelidikan tentang afasia sering melibatkan golongan dewasa yang berbeza umur. Walau bagaimanapun, para pengkaji afasia jarang membincangkan proses penuaan dalam melaporkan kaedah dan hasil penyelidikan. Objektif kami adalah untuk: (a) mengenalpasti corak pelaporan dan pengawalan kesan penuaan, dan (b) membincangkan kaedah yang berpotensi dalam mengambilkira kesan penuaan ke atas reka bentuk kajian afasia. Carian artikel dilakukan di laman PubMed bagi penerbitan dalam tahun 2015 sehingga 2020. Penyelidik secara individu telah menyaring tajuk and abstrak bagi artikel yang dikenalpasti. Saringan teks penuh telah dilakukan oleh pengarang pertama dan ketiga berdasarkan kriteria inklusif. Hanya satu artikel sahaja (daripada 53 buah artikel) yang tidak melaporkan umur kronologikal peserta kajian. Walau bagaimanapun, kurang daripada 50% artikel yang disemak telah menerangkan kaedah pengawalan kesan penuaan dan aplikasi konsep gerontologi dalam penyelidikan. Kesan penuaan yang dilaporkan tertumpu kepada perubahan biofisiologikal yang dikaitkan dengan umur. Kefahaman terhadap tahap kompleksiti proses penuaan dan pengaplikasian kaedah yang juga mengambilkira pelbagai jenis kesan penuaan, seperti kesan kohort dan kesan jangkamasa mungkin akan dapat mempertingkatkan mutu reka bentuk kajian dan interpretasi dapatan kajian afasia.

Kata kunci: Afasia; warga emas; penuaan; penyelidikan; tinjauan kepustakaan

INTRODUCTION

AGE AND APHASIA

Aphasia is a language disorder characterized by difficulties understanding and producing language in auditory-verbal, textual, and signed forms due to brain damage (Hallowell 2017). Aphasia research is

conducted to understand the nature of aphasia and its impact on the lives of people with aphasia and their caregivers. Moreover, it helps researchers and clinicians identify the best evaluation and intervention methods to support recovery (Damico et al., 1999). Previous research has shown the relationship between age and aphasia in terms of its nature, occurrences, and consequences in life.

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Engelter et al. (2006) found that the risk of aphasia increases by 3% for every additional year of age.

Additionally, they reported that the frequency of aphasia increases from 15% among stroke survivors between 65-84 years old to 45% among those age 85 years or older. In other studies (e.g., Ceccaldi et al.

1996; Ellis & Urban 2016; Flowers et al. 2016), aphasia that occurs in older populations tends to be more severe, as individuals tend to experience language impairments to a larger extent. Regardless of aphasia severity, its impacts on quality of life can still be disconcerting. Cruice, Worrall and Hickson (2010) reported that older adults with aphasia demonstrated low quality of life due to limitations to socially engage with others, participate in volunteering work, and appreciate leisure pursuits and entertainment. Among younger population, Dalemans and colleagues (2008) found that people with aphasia tend to experience job loss, a shift in responsibilities from “self” to spouse and other family members, and a reduced social network.

In aphasia studies, the age of participants has been consistently reported (de Vries, Sloot &

Achterberg 2017; Hallowell 2009; Zhang et al. 2016).

Yet, there are different classifications for age. In this context, age that is measured based on the duration of time between birth and the present day in which a person is living is known as “chronological age”

(Morgan & Kunkel 2011). However, there is varying consensus for the chronological ages that serve as a marker to identify the parameters of each age group in adulthood: young, middle-age, and older adults.

Furthermore, to help distinguish the age cohort- related characteristics of those in older adulthood, gerontology researchers recognize three age segments: young-old (age 65 to 74), middle-old (age 75 to 84) and oldest-old (age 85 and above).

However, it is not uncommon to find research in non- gerontology disciplines that identifies the ages of 55, 60, 65, and 70 years as the beginning of older adulthood. This is significant because when the phrase “older adults” or “older adulthood” is used in various academic and research arenas, it can represent an ill-defined variable.

Aphasia studies typically include older adults because of the high risk of stroke and aphasia in this population. Despite the effect of age on the nature of aphasia and its impacts on one’s experience, there is a lack of consistency among aphasia researchers in determining the roles of age as a variable and how it is considered and controlled in relation to the study’s objectives, analysis, and findings. Lack of a set age- criteria or age-related guidelines may result in difficulties in replicating studies and comparing findings across the discipline. This is because “older adults” in some studies may largely represent

individuals as young as age 50; whereas, the “older adults” in others may largely represent individuals age 70 and older. Without having shared chronological age parameters, it is also problematic for scholars to pose specific statements about aphasia for the respective age groups.

THE COMPLEXITY OF AGING PROCESS Gerontology is an academic field of study that explores and strives to explain the aging experience in older adulthood and includes a range of perspectives, from biological to sociological.

Although gerontology focuses on older adulthood, this includes an awareness and appreciation for aging across the entire lifespan, as a person does not just

“arrive” in older adulthood. Rather, they are shaped by forces across their entire life.

Aging is a complex process that includes physiological changes, health status, mental functioning, cognitive abilities, emotional state, and social interaction that work in tandem. From a biological standpoint, age-related changes occur in a widespread manner due to interconnectivity between body systems and functions at the cellular level (Geerlings et al. 2015). Differences among individuals may be hereditary and can be accelerated or decelerated by external factors, such as lifestyle, environments, and personal experiences (Kirkwood 2005; Salthouse1991). For example, a 67-year-old who has a history of high blood pressure and diabetes mellitus in her family and is aware of health consequences, may modify her health behavior to include regular medical screenings or an improved diet. However, her level of health literacy, access to care, and financial resources can strongly influence this. In addition, all of these influencers change over time—from day to day, year to year—and will continuously shape her health and wellbeing. Thus, there may be substantial variability in assessing health-related and lifestyle factors among women in their 60s, for example, who are at-risk for stroke and post-stroke aphasia.

Researchers who assess age as a variable or assign participants into age categories also need to be aware of the three types of effects that may influence a study’s findings: age effects, cohort effects, and period effects (Morgan & Kunkel 2011; Weil 2015).

Age effects refer to gradual changes that occur as an individual grows older and can be attributed to age.

An example of this is the greying of hair that is typically experienced by most persons as they age from their middle-aged years into older adulthood.

Cohort effects refer to shared characteristics among individuals within the same age cohort. Weil (2015) defined cohorts as a group of people within certain

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time intervals. Typically, this is represented by persons who are born within an identified window of time. For example, in some countries, the term

“Baby Boomer” is used to identify the age cohort that was born between 1946 and 1964. For example, teenagers today tend to be tech savvy and well- connected on social media because they were born into a world where digital technology is pervasive.

In comparison, although there is an increasing proportion of older adults who use and are comfortable with using digital technology, it is not to the same degree as younger individuals. Finally, period effects refer to the influence of specific historical events on individuals of multiple cohorts.

For example, at the time of this writing, most persons are affected to varying degrees by the COVID-19 pandemic. Although the pandemic is shaping the lives of individuals in different ways, this global event is being experienced by a multitude of persons who represent the entire lifespan. So, just as a school-aged children have been impacted, so too, have older adults.

As one can see, there are a multitude of factors to take into consideration when examining age as a variable. Without due diligence, it can be irresponsible and ethically unsound to lump populations together by ill-defined chronological age categories alone. By overlooking the complexities that shape and classify older adulthood, validity is at risk due to the potentially confounding variables and misinterpretations of findings. The objective of this scoping review is two-fold: (a) to identify trends in documenting and controlling aging effects in aphasia research and (b) to discuss potential methods that may be applicable in accounting for aging effects when involving individuals across age groups in studying aphasia.

METHODS AND ANALYSIS

The protocol for this scoping review was developed based on the frameworks proposed by Peters et al.

(2015) and Tricco et al. (2018). A literature search was conducted on PubMed database for the period between 2015 and 2020. The latest search was conducted on June 21^st, 2020. The following Boolean terms and phrases were used: “aphasia” AND "older adults" or "elderly" or "geriatric" or "geriatrics" or

"aging" or "senior" or "seniors" or "older people" or

"aged 65” or "65+". The authors independently screened different lists of article titles and abstracts to determine which ones merited further review. The selected articles were then screened by the first and third author to confirm the selection of articles for full-text screening. Identification of articles for full-

text review were based on the following criteria: (a) the journal publication was in English, (b) the journal publication reported an original study, (c) the journal publication reported older adults as participants, (d) the journal publication focused on a population with sudden onset aphasia. The selected articles identified for full-text screening were reviewed to address the objectives.

RESULTS

Our search on PubMed resulted in 458 articles related to aphasia and older adulthood. As shown in Figure 1, 154 articles met the inclusion criteria through the initial title and abstract screening. Articles that were excluded at this stage were studies that did not focus on sudden onset aphasia, such as primary progressive aphasia, dementia, and dysarthria. Other excluded articles included literature reviews and conference proceedings. Full-text assessments further excluded 101 articles, including those that: lacked identification to determine older adults’ participation, lacked participation of people with aphasia, did not focus on sudden onset aphasia, and reports on study protocols. This resulted in a total of 53 articles that met all inclusion criteria.

As shown in Table 1, 98.1% (n = 52) articles reported chronological age in the form of means, standard deviations, and/or ranges. Only one article did not document on the participants’ chronological age but stated that “older adults” were enrolled as participants. Studies that involved fewer than 20 participants with aphasia (PWA) typically reported the age of each participant. Eleven studies were found to categorize participants into age groups according to chronological age (e.g., younger adults, older adults) . It was noted that 21 articles accounted for age as a variable by chronological age, but only 14 of those (66.7%) reported methods for ensuring similarities of age range or means between study groups, primarily by performing statistical analysis.

Two out of the remaining seven articles reported a specific age range or cut-offs, while the other five articles reported matching study groups by age without specifying their methods.

Despite the subject matter of the studies (i.e., aphasia), only sixteen articles referred to gerontological concepts. Age-related biophysiological changes were most often mentioned in those articles (57%, n = 8). Other gerontological concepts presented in those articles included:

integration of aging effects with biopsychosocial factors, cohort effects, and pathological versus normative aging processes. It was noted that none of the articles related or discussed those concepts to social gerontology.

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FIGURE 1 Flowchart of article selection process

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TABLE 1 Documentation, grouping, control method and gerontological concepts in aphasia studies

Publication authors and year

Sample size Any documentation of participants' age?

Any grouping according to age?

Any control imposed on age?

Any discussion relevant to gerontological concepts?

Akanuma et al.

(2016)

10 PWA Yes. Individual age and age range No No No

Al-Shdifat, Sarsak &

Ghareeb (2018)

1 PWA Yes. Individual age N/A N/A No

Bakhtiyari et al.

(2015)

15 PWA Yes. Individual age, age range, mean

and standard deviation

No No No

Britt, Ferrara, &

Mirman (2016)

Experiment 1:50 young adult participants (Control 1) Experiment 2: 17 older adult participants (Control 2) Experiment 3: 13 PWA

Yes. Age range, mean and standard deviation

Yes Yes. Specific age cut-offs for young versus older group.

Yes. Age-related biophysiological changes (i.e., cognitive processing)

Botezatu & Mirman (2019)

19 PWA

15 older adult participants (control)

Yes. Age range, mean and standard deviation for each group, and individual ages of PWA group

No No No

Bullier et al. (2020) 32 PWA Yes. Age range, mean and standard deviation

No No No

Chang et al. (2016) 14 PWA

16 young adult participants (Control 1)

7 older adult participants (Control 2)

Yes. Age range, mean and standard deviation for each group, and individual ages of older participants and PWA

Yes Yes. Statistical comparisons between groups

Conner et al. (2018) 1 PWA Yes. Individual age N/A N/A No

Evans, Hula & Starns (2019)

20 PWA

22 control participants

Yes. Age range, mean and standard deviation for each group, and individual ages for PWA group

No Yes. Groups were

matched

according to age;

no statistical comparisons

No

Fergadiotis et al.

(2019)

47 PWA Yes. Age range, mean and standard

deviation

No No No

Fieder et al. (2015) 2 PWA

Yes. PWA individual ages. Yes No No

Continue...

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...continued Publication authors and year

Sample size Any documentation of participants’

age?

Fossett et al. (2016) 16 PWA

Yes. Age range, mean and standard deviation for each group, and individual ages of PWA

No Yes. Groups were

matched

according to age;

No

Fyndanis et al. (2018) 8 PWA

Yes. Mean and standard deviation for each group, age range for control group, and individual ages of PWA

No No No

Fyndanis &

Themistocleous (2018)

8 PWA

Yes. Age range, mean and standard deviation for each group, and individual ages of PWA

No No Yes. Integration of

aging effects with biopsychosocial factors.

Gravier et al. (2018) 17 PWA Yes. Individual participants’ ages No No No

Hayes, Dickey &

Warren (2016)

12 PWA

Higgins et al. (2020) 65 PWA

Yes. Age mean and standard deviation

No No No

Hreha et al. (2017) 40 PWA Yes. Age range, mean and standard deviation

No No No

Kang et al. (2016) 111 PWA Yes. Age mean and standard

deviation

No Yes. Statistical comparisons between groups

No

Kasselimis et al.

(2017)

deviation

No No No

Kljajevic et al. (2019) 7 PWA

Yes. Individual participants’ ages No Yes. Statistical comparisons between groups

No

Koleck et al. (2017) 101 PWA Yes. Age mean and standard deviation

No No No

Continue...

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age?

Kong, Whiteside &

Bargmann (2016)

12 PWA

13 adults with dementia 60 control participants

Yes. Age range, mean and standard deviation for each group, and individual ages of PWA and adults with dementia

Yes No No

Law, Kong & Lai (2018)

65 PWA

Yes. Age range, mean and standard deviation

Yes, heterogenous life experience across adulthood Lee J. et al. (2019) 18 PWA

Yes. Age range and mean No No No

Lee H. et al. (2015) 30 PWA

No Yes. Groups were

matched

according to age;

No

Lee, Yoshida, &

Thompson (2015)

12 PWA

16 young adults (Control 1) 12 control participants matched according to PWA age (Control 2)

No

Mack, Nerantzini &

Thompson (2017)

11 PWA

10 older adult participants (control)

No

Macoir et al. (2017) 20 PWA Yes. Age range and individual participants’ ages

No No No

Man et al. (2019) 17 PWA

Yes. Age range and mean. No No No

Meier et al. (2019) 34 PWA Yes. Individual participants’ ages No No No

Menger, Morris &

Salis (2020)

25 PWA

Yes. Age range, mean and standard deviation for each group

Yes. Cohort effects and personal beliefs.

Continue...

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age?

Mohapatra &

Marshall (2019)

10 PWA

Murray (2018) 23 PWA

No No Yes. Statistical

comparisons between groups

No

Osawa & Maeshima (2016)

115 participants with thalamic hemorrhagic stroke

Yes. Mean age and standard deviation.

No No No

Palmer et al. (2020) 270 PWA Yes. Age range, median, mean and standard deviation

No No No

Palmer, Hughes &

Chater (2017)

100 PWA Yes. Age range and median Yes Yes. A specific

age cut-off was used to define older PWA group.

Yes. Overlaps between interests of older adults as compared to the younger population.

Peñaloza et al. (2015) 14 PWA

120 young adult participants (Control 1), 14older adult participants (Control 2)

Yes Yes, PWA and

Control 2 groups matched roughly according to age.

No statistical analysis reported.

Peñaloza et al. (2017) 16 PWA

39 young adult participants

Yes. Age range, mean and standard deviation for each group

Yes.

Raglio et al. (2016) 10 PWA Yes. Individual participants’ ages. No No No

Räling, Schröder &

Wartenburger (2016)

9 PWA

Saldert et al. (2018) 4 PWA-nurse dyads Yes. Individual participants’ ages No No No

Sharma et al. (2019) 294 PWA Yes. Mean age. No. No No

Continue...

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Sample size Any documentation of participants' age?

Sitren & Vallila- Rohter (2019)

16 PWA

Yes. Age range according to groups and individual ages of PWA

Yes No Yes. Cohort effects.

Soares et al. (2018) 36 PWA Yes. Age range and median. No No No

Szymaszek, Wolak &

Szelag (2017)

14 PWA Yes. Individual age, age range, mean,

and standard deviation

Tatsumi et al. (2016) 110 PWA-caregiver dyads Yes. Mean age and standard deviation.

No No No

Valiengo et al. (2016) 4 PWA Yes. Mean age and individual participants' ages.

No No No

Warren, Dickey &

Lei (2016)

18 PWA

Yes. Age range, mean, and individual ages of PWA

No Yes, groups were

roughly matched according to age.

No statistical analysis reported.

Wilmskoetter et al.

(2019)

deviation.

No No No

Woods et al. (2016) 1 PWA Yes. Individual age N/A N/A Yes. Pathological

aging.

Xin et al. (2019) 19 PWA

19 stroke survivors without aphasia

Yes. Mean age and standard deviation.

No

Zhang et al. (2018) 25 PWA with normal hearing 8 PWA with hearing loss 30 control participants with normal hearing (Control 1) 42 control partcipants with hearing loss (Control 2)

Yes. Age range and mean. No No Yes. Age-related

biophysiological changes (i.e., hearing level)

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DISCUSSION

AGE AS A VARIABLE: TRENDS IN APHASIA RESEARCH

In the current review, almost all articles reported participants’ chronological ages in the form of actual individual age and/or descriptive analysis output (i.e., means, standard deviations, and ranges). This is similar to previous reviews that explored participant descriptions in aphasia studies (de Vries et al. 2017, Hallowell 2009, Zhang et al. 2016). Although many articles reported chronological age, its influence on study design and study findings were not discussed in detail. Articles that mentioned aging effects or age- related processes did so within the context of age- related groupings. Less than half of the reviewed studies mentioned aging effects on biophysiological changes, and fewer mentioned aging effects related to psychosocial changes. It can be proposed that the authors of these articles may not have included such content due to aspects such as publication constraints, such as word count, or it was not a primary aim for analysis within the study.

In addition, the extent to which a study may provide detailed demographics, or a description of participants’ characteristics can be associated with its research designs (e.g., qualitative, quantitative, or mixed-method designs). For example, in the reviewed studies, those that were qualitative in nature were more likely to expand upon participant characteristics. This tends to be more appropriate and common in qualitative studies as compared to quantitative studies, depending on the study’s objectives. Nonetheless, due to the complex nature of the aging process—i.e., how a person is influenced physically, emotionally, and socially—age should be discussed and considered in more details, rather than just a number in the participants’ background.

Aphasia influences an older adult in more ways than just speaking. It may, for example, affect their ability to nurture important relationships, which becomes increasingly important in old age (Cartensen, 1995).

In turn, this may influence an older adult’s sense of well-being and quality of life.

It was also noted that only one article thoroughly discussed the need to consider aging effects (i.e., Menger, Morris & Salis 2020), whereas other articles briefly included a description of aging or cohort effects. For example, in a study that assessed topics and vocabulary in oral narratives of adults with and without aphasia, Law et al. (2018) discussed how narration styles of older individuals differ from younger persons. This included the elaboration of life history, strong attitudes toward life issues, and linkages between past and present. The authors also

highlighted the importance for speech-language therapists to consider topics that are more relevant for older adults during their treatment sessions.

Sitren and Vallila-Rohter (2019) also briefly discussed differences between age cohorts when assessing iPad navigation skills among study participants with and without aphasia. According to the authors, frequency of usage, as well as comfort and familiarity with technology tend to differ between older and younger individuals despite increasing exposure and access to different types of technology among older adults. They suggested that this difference should be considered in studies similar to theirs. This idea was explored in another identified study. Menger et al. (2020) found that age- related functional decline may cause a barrier to digital technology use and dedicated a section in their discussion focusing on this relationship. Their discussion touched upon a wide range of issues, including an adult’s personal beliefs regarding technology use, the evolution of lifestyles and adoption of technologies as the younger population grows older, and the impacts of biological changes that naturally occur as people age.

ACCOUNTING FOR AGING EFFECTS IN APHASIA STUDIES

A review of the identified studies suggests that age is more than just a variable to be recognized and accounted for. Rather, it is a variable that varies among research on studies that aim to assess aphasia in older populations. This can prove to be a problematic, as there are assumptions that are associated with select ages and this creates an opportunity for misunderstanding and erroneous conclusions.

A number of studies in this review conducted comparisons of performances between young versus older adults. This is common in cognitive aging studies (Salthouse 1991). Some studies in the current review also employed this approach by comparing performances between young adults, older adults, and PWA. In controlling aging effects, we found that some researchers statistically compared the mean age of participants; however, the application of statistical analysis on age as an independent variable was inconsistent. A number of studies that included a larger sample size did not analyze group differences in terms of age. Appropriate applications of statistical analysis, such as between-group independent t-test, are recommended for controlling aging effects (Salthouse 2011; Victor, Westerhof & Bond 2007).

As highlighted earlier, age, cohort, and period effects must be considered when researching aging and old age experiences (Victor et al. 2007).

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Nesselroade (2006) proposed for an increase of longitudinal studies, where age is treated as a continuous factor. However, longitudinal approach has its own challenges, especially to reduce the attrition rate related to death, loss of contact, or lack of interest in continuous participation in research (Victor et al. 2007). To address continuous age- related changes, Victor et al. (2007) suggested the sequential approach, which combines both between- group cross-sectional and longitudinal approaches.

Generally, in studies that apply the sequential approach described above, recruited participants are pooled into age groups from young to old. The same participants are then recruited again after a specified period to reflect the longitudinal effect of aging.

During the second recruitment point, a new cohort of younger participants are recruited. This new cohort is then included in the study for the second time during the third recruitment point. The cycle is continued until the end of the study period. Time-lag approach was suggested to increase the validity of aging effects, while addressing cohort and period effects.

Use of appropriate materials and measurement methods are crucial for high quality research (Pourhoseingholi, Baghestani & Vahedi 2012).

Victor et al. (2007) argued that psychometrics of measurement tools for older adults must be established prior to studies. In standardizing the Psycholinguistic Assessment of Language (PAL), Caplan et al. (2007) found that all participants without aphasia, regardless of age, performed at above 90% accuracy in most subtests (Phoneme Discrimination, Auditory Lexical Decision, Auditory Word-Picture Matching, Word Repetition, and Picture Naming). However, older adults without aphasia (70 years and older) performed between 78- 88% accuracy in the non-word repetition task as compared to other participants (younger than 70 years of age) who performed at 94% and above. This shows that the validity and reliability of some measures may be affected by aging effects, which should be disclosed by researchers. Without the disclosure, clinicians might believe that all adults tested for the non-word repetition task performed at 90% or higher.

Physical limitations may be confounding factors even among self-reported healthy older adults.

Limitations are even more prominent among people with aphasia who have sensory or motoric limitations (Hallowell 2017). In addition to traditional behavioral measures, such as speed and accuracy, methods that rely on non-behavioral or reflex responses (e.g., imaging, eyetracking, pupillometry, and event-related potential) might provide additional insights based on the findings of these studies (Chapman & Hallowell 2015, Hallowell, Wertz & Kruse 2002, Crosson et al.

2007). These methods bypass some physical limitations for evaluating the performance of participants with aphasia. Insights from non- behavioral or reflex responses might provide support to the interpretation of these findings.

CONCLUSION

Despite the different approaches, all studies that control for the age of participants with and without aphasia have similar end goals, which is to understand how aphasia affects language functions.

However, serious consideration should be given towards the understanding of age as a variable when studying aphasia. Age should not be simply reported, but should be acknowledged and controlled as and when necessary. Clear justifications on employing one approach over another when controlling for age is warranted to support researchers’ arguments and suggestions to support their findings.

In order to accurately interpret and apply research findings in clinical practice, variations of experience over the course of one’s life (i.e., life course factors) must be acknowledged and understood in terms of how such factors shape the adult’s life in the context of aphasia. It is also inadequate to simply compare the differences in performance between individuals with or without aphasia without appreciating other individual factors and how those individual factors interact with each other. Furthermore, it is crucial to understand the changes of language use as people age because this may have an impact on the social roles and interactions among older adults. This may also play a role with respect to how therapeutic approaches and services could be tailored for older adults with aphasia. Such an approach may prove invaluable to assess in intervention studies. Because there is a dearth of research on age-related language changes in older adulthood within the context of meaningful social settings, a more thorough exploration is merited. This would provide insight into the intersection of aphasia and normative age-related changes in social communication across different generations.

This review included all studies that involved older participants with aphasia, but not necessarily focusing on biological or social changes of language and communication functioning across adulthood. This review is also far from being exhaustive. Search on other databases may result in study reports that describe and discuss how aging effects affected the study’s methods and findings.

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ACKNOWLEDGEMENT

We thank our institutional affiliations for supporting this collaboration. We extend our gratitude to Mr.

Armand Faizal for his assistance in preparing the review.

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Fatimah Hani Hassan

Center for Rehabilitation and Special Needs Studies Faculty of Health Sciences

Universiti Kebangsaan Malaysia 50300 Jalan Raja Muda Abdul Aziz Wilayah Persekutuan Kuala Lumpur Malaysia

Julie Brown

College of Health Sciences and Professions Ohio University, Athens, Ohio 45701

United States of America Nabihah Ismail

Rehabilitation Department Penawar Special Learning Centre Jalan H1, 53100 Taman Melawati, Wilayah Persekutuan Kuala Lumpur Malaysia

An Dinh

College of Health and Human Services, School of Intervention and Wellness The University of Toledo

2801 W, Bancroft St., Toledo, OH 43606 United States of America

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Corresponding Author: Fatimah Hani Hassan E-mail: [email protected]

Tel: +60392895011 Fax: +60326914304 Received: 27 August 2021 Revised: 18 November 2021

Accepted for publication: 9 March 2022