RESEARCH ARTICLE
Daily crosswords improve verbal fluency: a brief intervention study Mike Murphy, Katie O’Sullivan and Kieran G. Kelleher School of Applied Psychology, University College Cork, Cork, Ireland Correspondence to: M. Murphy, E-mail: [email protected]
Phonemic verbal fluency (PVF) is a cognitive function that involves serial processes termed clustering and switching and which is impacted in both normal aging and dementia. The cognitive reserve hypothesis suggests that appropriate cognitive stimulation could maintain or improve cognitive performance. This study examines the effect on PVF performance of a brief crossword-based intervention in a cognitively normal, community-based sample. Methods: Thirty-seven members of active retirement groups volunteered to participate and were randomly assigned to a crossword group and a control group. The former attempted a crossword daily for 4 weeks while the latter kept a daily gratitude diary for the same period. Results: 2 × 2 mixed analyses of variance revealed that the crossword group performed significantly better over time than the control group in both total PVF score and in the cluster size component. Conclusion: Daily crosswords may be a simple and effective means of bolstering PVF performance in older people. Copyright # 2014 John Wiley & Sons, Ltd.
Objective:
Key words: verbal fluency; aging; cognitive reserve; crosswords; intervention History: Received 1 August 2013; Accepted 23 December 2013; Published online 3 February 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/gps.4079
Verbal fluency can be defined as ‘the expressive ability to produce linguistic output’ (Sternberg, 2009) and is a fundamental contributor to communication. One form of verbal fluency is phonemic verbal fluency (PVF), which relates to words that are linked through shared initial letters. The approach to assessing PVF in research is through the Controlled Oral Word Association Test (COWAT), wherein participants are invited to name as many words as possible in 1 min, which begin with a specified letter (typically F, A, S; Miller, 1984). Performance in PVF involves selecting subcategories serially, generating as many words as possible within one subcategory before moving on to the next. The cognitive processes involved in this task are termed ‘clustering’ and ‘switching’ (Troyer, 2000). Clustering refers to the generation of words that belong to a shared subcategory. In PVF, these subcategories can be words which begin with the same two first letters, share the same first and last sounds, rhyme, or are homonyms (Troyer et al., 1997)—in Copyright # 2014 John Wiley & Sons, Ltd.
other words, they are linked in terms of surface or superficial structure and not in terms of meaning. Switching, the complement to clustering, is the transition from one subcategory to another—i.e. where one subcategory has been exhausted, another is selected to replace it as the focus of word generation. Troyer (2000) suggests, on the basis of brain damage studies, that clustering is related to temporal lobe function, whereas switching is a frontal lobe task. A more recent neuroimaging study of 16 older adults, however, identified activity primarily in the frontal lobes and partly in the parietal lobes during PVF tasks (Meinzer et al., 2009). Nickerson (2011) speaks in terms of active and passive approaches to word list generation, including a strategic ‘generate-and-test’ approach where potential candidates for inclusions are considered and accepted or rejected; this approach could be considered applicable to both clustering and switching. Phonemic verbal fluency is of interest to the area of gerontology for a number of reasons. It has tended to be less of a focus of research in older adults than Int J Geriatr Psychiatry 2014; 29: 915–919
M. Murphy et al.
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semantic verbal fluency as it has been considered less prone to age-related change (e.g. Mathuranath et al., 2003)—a recent meta-analysis, however, has identified a decline in PVF from approximately 60 years of age, accelerating with advancing age (Rodriguez-Aranda and Martinussen, 2006). In addition, a meta-analysis by Henry et al. (2004) found a large deficit in PVF performance in people suffering from Alzheimer’s Disease. Thus, it is clearly desirable to maintain and enhance PVF performance as far as possible in older people. But how might this be carried out? One possible route is through the harnessing of cognitive reserve. The cognitive reserve hypothesis (e.g. Stern, 2002) is derived from the observation that those with inter alia, higher education levels, or greater levels of cognitively-based leisure activity are less likely to develop Alzheimer’s disease (Stern et al., 1994; Scarmeas et al., 2001). Further research identified a similar association between these factors and cognitive performance in non-dementing samples (e.g. Le Carret et al., 2003; Singh-Manoux et al., 2003). Arising from this research, it was proposed that these factors might serve to ameliorate the effects of age-related neurodegeneration, through two possible mechanisms—hardware and software. The hardware approach suggest that greater intellectual activity at any point throughout life can stimulate the development of new neurons or of dendritic connections between neurons; therefore, those with higher levels of education or cognitive leisure are likely to have a physical buffer against neuronal and/or dendritic loss, with their associated cognitive consequences. Conversely, the software approach suggests that greater cognitive activity will lead to increased efficiency in cognitive processing, such that efficient alternative pathways are available for use. The vast bulk of the evidence in relation to cognitive reserve, however, is cross-sectional; whether the relationships identified are causal is a different matter, requiring further research (Harvard Mental Health Letter, 2006). To pursue such research, of course, requires a method for improving cognitive reserve in relation to the task to hand. On the basis of connectionist models suggesting that experience of shared activation strengthens links between related concepts and characteristics (Rumelhart et al., 1986), and of the findings of Maguire et al. (2000) that taxi drivers with greater experience had greater volume specifically in the navigation-related right posterior hippocampus, it is to be expected that tasks that are similar in form to the cognitive functions in question are likely to be the most effective in yielding improved performance. In relation to PVF, an obvious candidate for such an intervention Copyright # 2014 John Wiley & Sons, Ltd.
is crossword puzzles. Previous research (Hambrick et al., 1999) has found correlations between proficiency in such puzzles and PVF performance, while Nickerson (2011) argues that the generate-and-test approach to verbal fluency tasks is the same as that employed in solving many crossword clues. On the basis of these ideas Murphy and Cunningham (2012) found an improvement in semantic verbal fluency among 74 emerging adults in a 4-week intervention study. The present study assesses the impact of a similar intervention in PVF performance in a sample of community-dwelling adults 57 years and older. Participants were requested to attempt a crossword puzzle, taken with permission from a national newspaper, on a daily basis for 4 weeks (the experimental group), or to complete a daily gratitude diary for 4 weeks (the control group). It was hypothesized that the experimental group would, over the course of the 4-week intervention, improve more than the control group on PVF performance. In the event of this hypothesis being accepted, it was further hypothesized that the experimental group would improve more than the control group on both clustering and switching. As previous research has indicated an association between verbal fluency and age (Rodriguez-Aranda and Martinussen, 2006), sex (Weiss et al., 2006), education level (Van der Elst et al., 2006), and depression level (Henry and Crawford, 2005), these variables were controlled.
Method Participants
Participants consisted of 37 community-dwelling volunteers (27 female, 10 male) from the greater Cork city area of Ireland. Ages ranged from 57 to 90 years, with a mean of 71.49 (SD = 8.29). All participants scored within the age-appropriate and educationappropriate normal ranges for the Mini mental state examination (MMSE) (Bravo and Hébert, 1997) and so were deemed cognitively normal. Those in receipt of anti-depressant and/or anxiolytic medication were excluded from participation.
Design
An experimental design, featuring an intervention and a control group and involving gathering of data both pre-intervention and post-intervention, was employed. Int J Geriatr Psychiatry 2014; 29: 915–919
Daily crosswords and verbal fluency
917
Materials
Ethics
Data on age, sex, and education level were gathered through a questionnaire. The MMSE (Folstein et al., 1975) was used to assess general cognitive functioning. This instrument assesses a variety of cognitive domains including memory, object naming, language, orientation to time and place, and is a commonly used measure in both research and clinical practice. The Geriatric Depression Scale (Yesavage et al., 1983) was employed to assess depressive symptoms. This is a 30-item scale, with each item having the response options of ‘yes’ or ‘no’. The scale was validated by its authors against Research Diagnostic Criteria and against both the Zung Self-rating Depression Scale and the Hamilton Rating Scale for Depression. In the present study, the scale had a Cronbach’s alpha of 0.83. Phonemic verbal fluency was assessed through a short version of the COWAT, wherein participants were invited to list as many words beginning with the letter ‘F’ as they could in 1 min. Harrison et al. (2000) found little advantage in three-letter versions of the test, and so the single-letter version was selected. The data gathered were used as total number of words, and also as mean cluster size and number of switches using the guidelines of Troyer et al. (1997). Therefore, a cluster’s size was calculated as the number of words included in the cluster in addition to the initial word (so two words had a cluster size of 1), whereas the number of switches was the number of changes between clusters. A mixture of simple and cryptic crosswords, taken with permission from a national newspaper, was used for the intervention.
This study was conducted with regard to the code of ethics of the Psychological Society of Ireland and received ethical approval from the Ethics Committee of the UCC School of Applied Psychology.
Procedure
Community groups involving older people in the greater Cork city area were contacted and asked for an opportunity to address their members. Several such groups agreed, and the study was explained both verbally and in writing to the members. Volunteers were randomly assigned to the crossword group or the control group; the former were asked to attempt one crossword daily for 4 weeks, whereas the latter were asked to keep a diary in which they daily recorded three things for which they felt grateful. At the initial meeting with volunteers, the demographic questionnaire, Geriatric Depression Scale, MMSE, and COWAT were performed; at the follow-up meeting, only the COWAT was performed. Copyright # 2014 John Wiley & Sons, Ltd.
Results Participants in this study were 37 cognitively normal, community-dwelling adults (27 female, 10 male), aged 57 to 90 years. The participants were randomly assigned to one of two groups – the experimental (crossword) group consisted of 19 participants, with 18 being assigned to the control (gratitude) group. T-tests were used to assess equivalence of the two groups in terms of the continuous control variables. No differences were found for MMSE score [t(35) = 0.71, p = 0.49], depression [t(35) = 0.54, p = 0.59] or age [t(35) = 0.36, p = 0.72]. Chi-squared tests were used to assess equivalence of the two groups in terms of categorical control variables. No differences were found for sex [χ 2(1) < 0.005, p > 0.995] or education level [χ 2(6) = 7.26, p = 0.3]. Inspection of the PVF data revealed one extreme data point. This was addressed through reducing it to one unit above the next lowest point as recommended by Tabachnick and Fidell (2007). A two-way mixed analysis of variance (ANOVA) was used to assess change over time in PVF performance in both the intervention and the control group. A significant one-way interaction emerged from the analysis [F (1, 35) = 3.17, p = 0.042, partial eta squared = 0.083] with a moderate effect size (Cohen, 1988). The data are presented visually in Figure 1. Post hoc analysis consisted of a series of four within-group and betweengroup t-tests. There was a significant improvement with a very large effect size (Cohen, 1988) in PVF
Figure 1 Phonemic verbal fluency scores at baseline and postintervention, including 95% confidence intervals.
Int J Geriatr Psychiatry 2014; 29: 915–919
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performance over time in the crossword group [t(18) = 3.69, p = 0.001, eta squared = 0.43], and the difference between the groups post-intervention was also significant with a moderate-to-large effect size [t(35) = 2.16, p = 0.019, eta squared = 0.12]. Following this analysis, two further 2-way mixed ANOVAs were performed to assess changes in both switching and cluster size. No interaction emerged for switches [F (1, 35) = 0.02, p = 0.45]. However, a significant interaction, with a moderate-to-large effect size (Cohen, 1988), emerged for cluster size [F (1, 35) = 4.85, p = 0.017, partial eta squared = 0.12]. Post hoc analyses, in the form of four within-group and between-group t-tests, were conducted. The change over time in the crossword group was significant, with a large effect size [t(18) = 2.16, p = 0.023, eta squared = 0.21], although there was a significant difference between the groups postintervention [t(35) = 1.90, p = 0.033, eta squared = 0.09] with a moderate effect size (Cohen, 1988). The data for cluster size are presented visually in Figure 2. Discussion The purpose of this research was to assess the impact of a brief crossword intervention on PVF in cognitively normal older adults. It was hypothesized that those participants who attempted daily crosswords for 4 weeks would show greater improvement than those who kept daily gratitude diaries. This hypothesis was supported. Two follow-up hypotheses were also tested—that the crossword group would improve more on both switching and cluster size; in this instance, the former hypothesis was not supported, whereas the latter was. The finding in relation to PVF performance matches that of Murphy and Cunningham (2012) in relation to semantic verbal fluency in younger adults. It is explicable with reference to the notion of cognitive
Figure 2 Cluster sizes at baseline and post-test, including 95% confidence intervals.
Copyright # 2014 John Wiley & Sons, Ltd.
M. Murphy et al.
reserve. This finding is consistent with a large body of work in the area of cognitive reserve (e.g. Elwood et al., 1999; Singh-Manoux et al., 2003), but the bulk of this research has been cross-sectional in form. This study suggests that it is possible, quite easily, to increase cognitive reserve in older people. The hardware approach to cognitive reserve would suggest that dendritic connections had developed to allow for more successful word finding, whereas the software approach would rather suggest that practice led to more efficient use of search processes. Considered in light of the strategic ‘generate-and-test’ approach to crossword puzzles and to word list generation outlined by Nickerson (2011), the results might be taken to suggest that it is indeed these search processes which have been impacted. The follow-up analyses addressed changes in switching and cluster size and found a significant improvement among the crossword group, but not the gratitude group, in the latter but not in the former. Thus, it seems that is clustering, the relatively effortless process of generating lists within a shared subcategory, that is impacted by this short-term intervention, with the more effortful switching process unaffected (Troyer, 2000). Nonetheless, whether it is through hardware or software, impacting clustering, or switching, the evidence indicates that the intervention does improve PVF. This finding has potentially useful implications. It is established that PVF performance falls off in older age (Rodriguez-Aranda and Martinussen, 2006) and is also negatively impacted in Alzheimer’s Disease (Henry et al., 2004). Declines in verbal fluency can of course have functional consequences; the present study suggests that a simple non-pharmacological intervention could be sufficient to build a reserve to counter the effects of neurodegeneration in older people. The study also suggests potential follow-up research. The present study found an impact of crosswords on PVF and specifically on clustering. Previous research (Murphy and Cunningham, 2012) has found an effect of crosswords on semantic verbal fluency in younger people. It may be that crosswords designed with specific purposes in mind could focus on improving or maintaining different types of function. In addition, this study addressed the question in a high functioning sample; future research should examine the matter, with appropriately crafted interventions, in dementing and/or brain-damaged populations. Were it possible to harness cognitive reserve successfully here, it would prove a very useful development. This research has limitations. The sample size is small, and derived from members of community groups in one city in Ireland; thus, it cannot be assumed that the results are generalizable to the general population Int J Geriatr Psychiatry 2014; 29: 915–919
Daily crosswords and verbal fluency
of elders. In addition, no measures were taken to ensure compliance by either the crossword or gratitude group. Nonetheless, the findings are consistent with theory and with previous research, and are of some interest. Conclusion In conclusion, this study found that a brief, simple intervention employing a commonly-used form of puzzle, improved PVF in a sample of communitydwelling older adults. This finding has possible implications for those with age-related PVF decline and may also offer benefits for those with verbal fluency loss arising from dementia or brain damage. Conflict of interest None declared.
Key points
• • •
Daily crosswords lead to improvement in phonemic verbal fluency performance. This effect is seen in total scores and in cluster size. Seen in light of cognitive reserve, this finding may point the way to developing specific cognitive tasks to meet specific needs.
References Bravo G, Hébert R. 1997. Age- and education-specific reference values for the MiniMental and modified Mini-Mental State Examinations derived from a nondemented elderly population. Int J Geriatr Psychiatry 12: 1008–1018. Cohen J. 1988. Statistical Power Analysis for the Behavioral Sciences (2nd edn). Academic Press: New York. Elwood PC, Gallacher JEJ, Hopkinson CA, et al. 1999. Smoking, drinking and other life style factors and cognitive function in men in the Caerphilly cohort. J Epidemiol Community Health 53: 9–14.
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919 Folstein MF, Folstein SE, McHugh PR. 1975. Mini-mental state: a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 12: 189–198. Hambrick DZ, Salthouse TA, Meinz EJ. 1999. Predictors of crossword puzzle proficiency and moderators of age-cognition relations. Journal Exp Psychol Gen 128: 131–164. Harrison JE, Bouxton P, Husain M, Wise R. 2000. Short test of semantic and phonological fluency: normal performance, validity and test-retest reliability. Br J Clin Psychol 39: 181–191. Harvard Mental Health Letter. 2006. Cognitive reserve. Harv Ment Health Lett 23(2): 3–4. Henry JD, Crawford JR. 2005. A meta-analytic review of verbal fluency deficits in depression. J Clin Exp Neuropsychol 27: 78–101. Henry JD, Crawford JR, Phillips LH. 2004. Verbal fluency performance in dementia of the Alzheimer’s type: a meta-analysis. Neuropsychologia 42: 1212–1222. Le Carret N, Lafont S, Letenneur L, et al. 2003. The effect of education on cognitive performances and its implication for the constitution of the cognitive reserve. Dev Neuropsychol 23: 317–337. Maguire EA, Gadian DG, Johnsrude IS, et al. 2000. Navigation-related structural change in the hippocampi of taxi drivers. Proc Natl Acad Sci 97: 4398–4403. Mathuranath PS, George A, Cherian PJ, et al. 2003. Effects of age, education and gender on verbal fluency. J Clin Exp Neuropsychol 25: 1057–1064. Meinzer M, Flaisch T, Wilser L, et al. 2009. Neural signatures of semantic and phonemic fluency in young and old adults. J Cogn Neurosci 10: 2007–2018. Miller E. 1984. Verbal fluency as a function of a measure of verbal intelligence and in relation to different types of cerebral pathology. Br J Clin Psychol 23: 53–57. Murphy M, Cunningham RK. 2012. A crossword a day improves verbal fluency: a report of an intervention study. Ir J Psychol 33: 193–198. Nickerson RS. 2011. Five down, absquatulated: crossword puzzle clues to how the mind works. Psychon Bull Rev 18: 217–241. Rodriguez-Aranda C, Martinussen M. 2006. Age-related differences in performance of phonemic verbal fluency measured by Controlled Oral Word Association Task (COWAT): a meta-analytic study. Dev Neuropsychol 30: 697–717. Rumelhart DE, Hinton GE, McClelland JL. 1986. A general framework for parallel distributed processing. In Parallel Distributed Processing: Explorations in the Microstructure of Cognition: Volume I, Rumelhart DE, McClelland JL, the PDP research group (eds). MIT Press: Cambridge, MA; 45–76. Scarmeas N, Levy G, Tang M, Manly J, Stern Y. 2001. Influence of leisure activity on the incidence of Alzheimer’s disease. Neurology 57: 2236–2242. Singh-Manoux A, Richards M, Marmot M. 2003. Leisure activities and cognitive function in middle age: evidence from the Whitehall II study. J Epidemiol Community Health 57: 907–913. Stern Y. 2002. What is cognitive reserve? Theory and research application of the reserve concept. J Int Neuropsychol Soc 8: 448–460. Stern Y, Gurland B, Tatemichi TK, et al. 1994. Influence of education and occupation on the incidence of Alzheimer’s disease. JAMA 271: 1004–1010. Sternberg RJ. 2009. Cognitive Psychology (5th edn). Wadsworth: California. Tabachnick BG, Fidell LS. 2007. Using Multivariate Statistics (5th edn). Allyn & Bacon: Boston. Troyer AK. 2000. Normative data for clustering and switching on verbal fluency tasks. J Clin Exp Neuropsychol 22: 370–378. Troyer AK, Moscovitch M, Winocur G. 1997. Clustering and switching as two components of verbal fluency: evidence from younger and older healthy adults. Neuropsychology 11: 138–146. Van der Elst W, van Boxtel MPJ, van Breukelen GJP, Jolles J. 2006. Normative data for the animal, profession and letter M naming verbal fluency tests for Dutch speaking participants and the effects of age, education and sex. J Int Neuropsychol Soc 12: 80–89. Weiss EM.,Ragland JD, Brensinger CM, et al. 2006. Sex differences in clustering and switching in verbal fluency tasks. J Int Neuropsychol Soc 12: 502–509. Yesavage JA, Brink TL, Rose TL, et al. 1983. Development and validation of a geriatric depression screening scale: a preliminary report. J Psychiatr Res 17: 37–49.
Int J Geriatr Psychiatry 2014; 29: 915–919
Daily crosswords improve verbal fluency: a brief intervention study Mike Murphy, Katie O’Sullivan and Kieran G. Kelleher School of Applied Psychology, University College Cork, Cork, Ireland Correspondence to: M. Murphy, E-mail: [email protected]
Phonemic verbal fluency (PVF) is a cognitive function that involves serial processes termed clustering and switching and which is impacted in both normal aging and dementia. The cognitive reserve hypothesis suggests that appropriate cognitive stimulation could maintain or improve cognitive performance. This study examines the effect on PVF performance of a brief crossword-based intervention in a cognitively normal, community-based sample. Methods: Thirty-seven members of active retirement groups volunteered to participate and were randomly assigned to a crossword group and a control group. The former attempted a crossword daily for 4 weeks while the latter kept a daily gratitude diary for the same period. Results: 2 × 2 mixed analyses of variance revealed that the crossword group performed significantly better over time than the control group in both total PVF score and in the cluster size component. Conclusion: Daily crosswords may be a simple and effective means of bolstering PVF performance in older people. Copyright # 2014 John Wiley & Sons, Ltd.
Objective:
Key words: verbal fluency; aging; cognitive reserve; crosswords; intervention History: Received 1 August 2013; Accepted 23 December 2013; Published online 3 February 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/gps.4079
Verbal fluency can be defined as ‘the expressive ability to produce linguistic output’ (Sternberg, 2009) and is a fundamental contributor to communication. One form of verbal fluency is phonemic verbal fluency (PVF), which relates to words that are linked through shared initial letters. The approach to assessing PVF in research is through the Controlled Oral Word Association Test (COWAT), wherein participants are invited to name as many words as possible in 1 min, which begin with a specified letter (typically F, A, S; Miller, 1984). Performance in PVF involves selecting subcategories serially, generating as many words as possible within one subcategory before moving on to the next. The cognitive processes involved in this task are termed ‘clustering’ and ‘switching’ (Troyer, 2000). Clustering refers to the generation of words that belong to a shared subcategory. In PVF, these subcategories can be words which begin with the same two first letters, share the same first and last sounds, rhyme, or are homonyms (Troyer et al., 1997)—in Copyright # 2014 John Wiley & Sons, Ltd.
other words, they are linked in terms of surface or superficial structure and not in terms of meaning. Switching, the complement to clustering, is the transition from one subcategory to another—i.e. where one subcategory has been exhausted, another is selected to replace it as the focus of word generation. Troyer (2000) suggests, on the basis of brain damage studies, that clustering is related to temporal lobe function, whereas switching is a frontal lobe task. A more recent neuroimaging study of 16 older adults, however, identified activity primarily in the frontal lobes and partly in the parietal lobes during PVF tasks (Meinzer et al., 2009). Nickerson (2011) speaks in terms of active and passive approaches to word list generation, including a strategic ‘generate-and-test’ approach where potential candidates for inclusions are considered and accepted or rejected; this approach could be considered applicable to both clustering and switching. Phonemic verbal fluency is of interest to the area of gerontology for a number of reasons. It has tended to be less of a focus of research in older adults than Int J Geriatr Psychiatry 2014; 29: 915–919
M. Murphy et al.
916
semantic verbal fluency as it has been considered less prone to age-related change (e.g. Mathuranath et al., 2003)—a recent meta-analysis, however, has identified a decline in PVF from approximately 60 years of age, accelerating with advancing age (Rodriguez-Aranda and Martinussen, 2006). In addition, a meta-analysis by Henry et al. (2004) found a large deficit in PVF performance in people suffering from Alzheimer’s Disease. Thus, it is clearly desirable to maintain and enhance PVF performance as far as possible in older people. But how might this be carried out? One possible route is through the harnessing of cognitive reserve. The cognitive reserve hypothesis (e.g. Stern, 2002) is derived from the observation that those with inter alia, higher education levels, or greater levels of cognitively-based leisure activity are less likely to develop Alzheimer’s disease (Stern et al., 1994; Scarmeas et al., 2001). Further research identified a similar association between these factors and cognitive performance in non-dementing samples (e.g. Le Carret et al., 2003; Singh-Manoux et al., 2003). Arising from this research, it was proposed that these factors might serve to ameliorate the effects of age-related neurodegeneration, through two possible mechanisms—hardware and software. The hardware approach suggest that greater intellectual activity at any point throughout life can stimulate the development of new neurons or of dendritic connections between neurons; therefore, those with higher levels of education or cognitive leisure are likely to have a physical buffer against neuronal and/or dendritic loss, with their associated cognitive consequences. Conversely, the software approach suggests that greater cognitive activity will lead to increased efficiency in cognitive processing, such that efficient alternative pathways are available for use. The vast bulk of the evidence in relation to cognitive reserve, however, is cross-sectional; whether the relationships identified are causal is a different matter, requiring further research (Harvard Mental Health Letter, 2006). To pursue such research, of course, requires a method for improving cognitive reserve in relation to the task to hand. On the basis of connectionist models suggesting that experience of shared activation strengthens links between related concepts and characteristics (Rumelhart et al., 1986), and of the findings of Maguire et al. (2000) that taxi drivers with greater experience had greater volume specifically in the navigation-related right posterior hippocampus, it is to be expected that tasks that are similar in form to the cognitive functions in question are likely to be the most effective in yielding improved performance. In relation to PVF, an obvious candidate for such an intervention Copyright # 2014 John Wiley & Sons, Ltd.
is crossword puzzles. Previous research (Hambrick et al., 1999) has found correlations between proficiency in such puzzles and PVF performance, while Nickerson (2011) argues that the generate-and-test approach to verbal fluency tasks is the same as that employed in solving many crossword clues. On the basis of these ideas Murphy and Cunningham (2012) found an improvement in semantic verbal fluency among 74 emerging adults in a 4-week intervention study. The present study assesses the impact of a similar intervention in PVF performance in a sample of community-dwelling adults 57 years and older. Participants were requested to attempt a crossword puzzle, taken with permission from a national newspaper, on a daily basis for 4 weeks (the experimental group), or to complete a daily gratitude diary for 4 weeks (the control group). It was hypothesized that the experimental group would, over the course of the 4-week intervention, improve more than the control group on PVF performance. In the event of this hypothesis being accepted, it was further hypothesized that the experimental group would improve more than the control group on both clustering and switching. As previous research has indicated an association between verbal fluency and age (Rodriguez-Aranda and Martinussen, 2006), sex (Weiss et al., 2006), education level (Van der Elst et al., 2006), and depression level (Henry and Crawford, 2005), these variables were controlled.
Method Participants
Participants consisted of 37 community-dwelling volunteers (27 female, 10 male) from the greater Cork city area of Ireland. Ages ranged from 57 to 90 years, with a mean of 71.49 (SD = 8.29). All participants scored within the age-appropriate and educationappropriate normal ranges for the Mini mental state examination (MMSE) (Bravo and Hébert, 1997) and so were deemed cognitively normal. Those in receipt of anti-depressant and/or anxiolytic medication were excluded from participation.
Design
An experimental design, featuring an intervention and a control group and involving gathering of data both pre-intervention and post-intervention, was employed. Int J Geriatr Psychiatry 2014; 29: 915–919
Daily crosswords and verbal fluency
917
Materials
Ethics
Data on age, sex, and education level were gathered through a questionnaire. The MMSE (Folstein et al., 1975) was used to assess general cognitive functioning. This instrument assesses a variety of cognitive domains including memory, object naming, language, orientation to time and place, and is a commonly used measure in both research and clinical practice. The Geriatric Depression Scale (Yesavage et al., 1983) was employed to assess depressive symptoms. This is a 30-item scale, with each item having the response options of ‘yes’ or ‘no’. The scale was validated by its authors against Research Diagnostic Criteria and against both the Zung Self-rating Depression Scale and the Hamilton Rating Scale for Depression. In the present study, the scale had a Cronbach’s alpha of 0.83. Phonemic verbal fluency was assessed through a short version of the COWAT, wherein participants were invited to list as many words beginning with the letter ‘F’ as they could in 1 min. Harrison et al. (2000) found little advantage in three-letter versions of the test, and so the single-letter version was selected. The data gathered were used as total number of words, and also as mean cluster size and number of switches using the guidelines of Troyer et al. (1997). Therefore, a cluster’s size was calculated as the number of words included in the cluster in addition to the initial word (so two words had a cluster size of 1), whereas the number of switches was the number of changes between clusters. A mixture of simple and cryptic crosswords, taken with permission from a national newspaper, was used for the intervention.
This study was conducted with regard to the code of ethics of the Psychological Society of Ireland and received ethical approval from the Ethics Committee of the UCC School of Applied Psychology.
Procedure
Community groups involving older people in the greater Cork city area were contacted and asked for an opportunity to address their members. Several such groups agreed, and the study was explained both verbally and in writing to the members. Volunteers were randomly assigned to the crossword group or the control group; the former were asked to attempt one crossword daily for 4 weeks, whereas the latter were asked to keep a diary in which they daily recorded three things for which they felt grateful. At the initial meeting with volunteers, the demographic questionnaire, Geriatric Depression Scale, MMSE, and COWAT were performed; at the follow-up meeting, only the COWAT was performed. Copyright # 2014 John Wiley & Sons, Ltd.
Results Participants in this study were 37 cognitively normal, community-dwelling adults (27 female, 10 male), aged 57 to 90 years. The participants were randomly assigned to one of two groups – the experimental (crossword) group consisted of 19 participants, with 18 being assigned to the control (gratitude) group. T-tests were used to assess equivalence of the two groups in terms of the continuous control variables. No differences were found for MMSE score [t(35) = 0.71, p = 0.49], depression [t(35) = 0.54, p = 0.59] or age [t(35) = 0.36, p = 0.72]. Chi-squared tests were used to assess equivalence of the two groups in terms of categorical control variables. No differences were found for sex [χ 2(1) < 0.005, p > 0.995] or education level [χ 2(6) = 7.26, p = 0.3]. Inspection of the PVF data revealed one extreme data point. This was addressed through reducing it to one unit above the next lowest point as recommended by Tabachnick and Fidell (2007). A two-way mixed analysis of variance (ANOVA) was used to assess change over time in PVF performance in both the intervention and the control group. A significant one-way interaction emerged from the analysis [F (1, 35) = 3.17, p = 0.042, partial eta squared = 0.083] with a moderate effect size (Cohen, 1988). The data are presented visually in Figure 1. Post hoc analysis consisted of a series of four within-group and betweengroup t-tests. There was a significant improvement with a very large effect size (Cohen, 1988) in PVF
Figure 1 Phonemic verbal fluency scores at baseline and postintervention, including 95% confidence intervals.
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performance over time in the crossword group [t(18) = 3.69, p = 0.001, eta squared = 0.43], and the difference between the groups post-intervention was also significant with a moderate-to-large effect size [t(35) = 2.16, p = 0.019, eta squared = 0.12]. Following this analysis, two further 2-way mixed ANOVAs were performed to assess changes in both switching and cluster size. No interaction emerged for switches [F (1, 35) = 0.02, p = 0.45]. However, a significant interaction, with a moderate-to-large effect size (Cohen, 1988), emerged for cluster size [F (1, 35) = 4.85, p = 0.017, partial eta squared = 0.12]. Post hoc analyses, in the form of four within-group and between-group t-tests, were conducted. The change over time in the crossword group was significant, with a large effect size [t(18) = 2.16, p = 0.023, eta squared = 0.21], although there was a significant difference between the groups postintervention [t(35) = 1.90, p = 0.033, eta squared = 0.09] with a moderate effect size (Cohen, 1988). The data for cluster size are presented visually in Figure 2. Discussion The purpose of this research was to assess the impact of a brief crossword intervention on PVF in cognitively normal older adults. It was hypothesized that those participants who attempted daily crosswords for 4 weeks would show greater improvement than those who kept daily gratitude diaries. This hypothesis was supported. Two follow-up hypotheses were also tested—that the crossword group would improve more on both switching and cluster size; in this instance, the former hypothesis was not supported, whereas the latter was. The finding in relation to PVF performance matches that of Murphy and Cunningham (2012) in relation to semantic verbal fluency in younger adults. It is explicable with reference to the notion of cognitive
Figure 2 Cluster sizes at baseline and post-test, including 95% confidence intervals.
Copyright # 2014 John Wiley & Sons, Ltd.
M. Murphy et al.
reserve. This finding is consistent with a large body of work in the area of cognitive reserve (e.g. Elwood et al., 1999; Singh-Manoux et al., 2003), but the bulk of this research has been cross-sectional in form. This study suggests that it is possible, quite easily, to increase cognitive reserve in older people. The hardware approach to cognitive reserve would suggest that dendritic connections had developed to allow for more successful word finding, whereas the software approach would rather suggest that practice led to more efficient use of search processes. Considered in light of the strategic ‘generate-and-test’ approach to crossword puzzles and to word list generation outlined by Nickerson (2011), the results might be taken to suggest that it is indeed these search processes which have been impacted. The follow-up analyses addressed changes in switching and cluster size and found a significant improvement among the crossword group, but not the gratitude group, in the latter but not in the former. Thus, it seems that is clustering, the relatively effortless process of generating lists within a shared subcategory, that is impacted by this short-term intervention, with the more effortful switching process unaffected (Troyer, 2000). Nonetheless, whether it is through hardware or software, impacting clustering, or switching, the evidence indicates that the intervention does improve PVF. This finding has potentially useful implications. It is established that PVF performance falls off in older age (Rodriguez-Aranda and Martinussen, 2006) and is also negatively impacted in Alzheimer’s Disease (Henry et al., 2004). Declines in verbal fluency can of course have functional consequences; the present study suggests that a simple non-pharmacological intervention could be sufficient to build a reserve to counter the effects of neurodegeneration in older people. The study also suggests potential follow-up research. The present study found an impact of crosswords on PVF and specifically on clustering. Previous research (Murphy and Cunningham, 2012) has found an effect of crosswords on semantic verbal fluency in younger people. It may be that crosswords designed with specific purposes in mind could focus on improving or maintaining different types of function. In addition, this study addressed the question in a high functioning sample; future research should examine the matter, with appropriately crafted interventions, in dementing and/or brain-damaged populations. Were it possible to harness cognitive reserve successfully here, it would prove a very useful development. This research has limitations. The sample size is small, and derived from members of community groups in one city in Ireland; thus, it cannot be assumed that the results are generalizable to the general population Int J Geriatr Psychiatry 2014; 29: 915–919
Daily crosswords and verbal fluency
of elders. In addition, no measures were taken to ensure compliance by either the crossword or gratitude group. Nonetheless, the findings are consistent with theory and with previous research, and are of some interest. Conclusion In conclusion, this study found that a brief, simple intervention employing a commonly-used form of puzzle, improved PVF in a sample of communitydwelling older adults. This finding has possible implications for those with age-related PVF decline and may also offer benefits for those with verbal fluency loss arising from dementia or brain damage. Conflict of interest None declared.
Key points
• • •
Daily crosswords lead to improvement in phonemic verbal fluency performance. This effect is seen in total scores and in cluster size. Seen in light of cognitive reserve, this finding may point the way to developing specific cognitive tasks to meet specific needs.
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