Effect of a 12-Week Regular Exercise Program on Cognitive Functional Change in Older Women
Article information
Abstract
OBJECTIVES
The present study aimed to investigate changes in cognitive function among older adults following a 12-week structured exercise program, using validated neuropsychological tests. The findings are intended to provide foundational evidence to inform the development and implementation of community-based health promotion programs for older women.
METHODS
This study was conducted 45 older adults. Participants were categorized into two groups according to the exercise group (n = 22) and control group (n = 23). All participants measured controlled oral word association test, trail making test, and digit span test before and 12 weeks after. The exercise group followed an exercise program of 60 minutes per session, three times a week, for 12 weeks.
RESULTS
For semantic and phonemic, there was no interaction between group and time. The exercise group showed a significant improvement in semantic (p < 0.05). There was a significantly different group and time on the trail making test (p < 0.05). The exercise group showed a significant improvement in the trail making test (p < 0.01). Forward and backward digit span test showed no interaction between group and time.
CONCLUSIONS
A 12-week regular exercise program showed significant improvements in semantic and trail making test results on the cognitive function in older adults. These results suggest that 12 weeks of regular exercise is highly effective in preventing or improving cognitive decline in older adults.
Introduction
With the rapid acceleration of global population aging, maintaining the physical and mental health of older adults has become a crucial public health priority. Cognitive decline, a condition commonly observed in the aging population, is increasingly recognized not only as a natural consequence of aging but also as a potential early indicator of neurodegenerative diseases, such as dementia. It represents a significant threat to individual autonomy and social independence, necessitating urgent attention [1]. Cognitive decline spans multiple domains, including memory, concentration, judgment, and problem-solving abilities. Moreover, it is closely associated with a reduced ability to perform activities of daily living, underscoring the importance of effective prevention and intervention strategies [2].
In this context, regular physical activity or exercise has received attention as a nonpharmacological intervention with proven beneficial effects on cognitive function in older adults. Recent evidence suggests that individuals who fail to meet the recommended physical activity thresholds (150 min of moderate-intensity exercise or 75 min of vigorous-intensity exercise per week) are approximately 2.29 times more likely to experience cognitive impairment than those who meet these thresholds. Moreover, older adults who remain completely inactive during the week have an approximately 1.22-fold higher risk of cognitive impairment than those who engage in physical activity even once a week [3]. These cognitive benefits are thought to be mediated by exercise-induced increases in hippocampal volume, resulting in improved memory, executive function, and processing speed [4]. Moreover, physical activity increases the secretion of brain-derived neurotrophic factor, activates the cerebral cortex, and promotes neuroplasticity, thereby improving overall brain health [5]. Given its low risk of adverse effects and favorable cost-effectiveness compared to pharmacological therapies, regular physical activity has substantial potential for integration into clinical and community-based health programs.
Cognitive function can be evaluated using various neuroimaging modalities, such as electroencephalography (EEG), magnetic resonance imaging, computed tomography, and positron emission tomography (PET) [6]; however, these methods are often impractical because of their high costs and procedural complexity. Moreover, they offer limited utility in detecting subtle cognitive impairments in certain domains, such as memory, attention, language, and perception. To overcome these limitations, various neuropsychological tests have been developed and validated for use in older populations. Widely used tests include the Controlled Oral Word Association Test (COWAT) for assessing verbal fluency and executive function (with particular emphasis on frontal lobe function); the Trail Making Test (TMT) for assessing visuomotor speed, attention, working memory, and executive function; and the Digit Span Test (DST) for assessing attention and working memory [7]. In particular, patients with mild cognitive impairment (MCI) had an average score of approximately 7 points lower than the cognitively normal group on the COWAT phonemic fluency task, and the effect size was 0.61, indicating an intermediate level, suggesting that the test has the ability to detect early changes in cognitive function [8]. In addition, COWAT semantic fluency shows a decline from the early stages of MCI and tends to gradually worsen until the mild Alzheimer’s stage, so semantic fluency is considered an indicator that can respond sensitively to the early stages of cognitive decline [9].
Empirical findings have demonstrated the positive effects of exercise on cognitive performance. In one study, a 12-week walking exercise intervention significantly improved COWAT scores among 33 older adults with cognitive decline, indicating enhanced memory function [10]. Similarly, high-intensity aerobic exercise has been found to substantially improve TMT performance, indicating gains in cognitive-motor integration [11]. Moderate-to-high-intensity resistance training has also been found to enhance DST scores, supporting the role of physical exercise in promoting cognitive health among older adults [12].
As the prevalence of cognitive impairment increases with aging, proactive screening and evaluation are crucial. However, the high cost of medical testing poses a barrier for many older individuals. Among the available nonpharmacological strategies, regular physical activity is one of the most accessible and effective options in terms of both safety and affordability. Importantly, cognitive changes in older adults can be assessed using simple neuropsychological tools that can be feasibly implemented in community centers and dementia care facilities. Hence, the present study aimed to assess changes in cognitive function among older adults following a 12-week structured exercise program by using validated neuropsychological tests. The findings will serve as foundational evidence to facilitate the development and implementation of community-based health promotion programs for older women.
Methods
Participants
A total of 45 elderly women aged ≥ 65 years were recruited for this study. The inclusion criteria were as follows: (1) female participants aged ≥ 65 years, (2) no prior diagnosis of dementia or cognitive impairment by a medical institution or physician, and (3) the ability to perform all components of the study protocol, including the exercise program. The participants were randomly assigned to either the exercise group (n = 22) or the control group (n = 23).
Before enrollment, all participants were provided a comprehensive explanation of the purpose of the study and the experimental procedures, and written informed consent was obtained. The study protocol was approved by the Institutional Review Board of [blinded for review] (IRB No. [blinded for review]).
The baseline physical characteristics of the participants are summarized in <Table 1>.
The characteristics of participants.
Body Composition
To assess the baseline physical characteristics of the participants, their body composition was measured using bioelectrical impedance analysis (InBody 470, Biospace Co., Ltd., Seoul, Korea); the analysis provided data on body weight and body fat percentage. Height was measured using a stadiometer and recorded to the nearest 0.1 cm. Body mass index was calculated by dividing the weight (kg) by the square of height (m2).
Cognitive Function Assessment
Three neuropsychological tests were conducted to evaluate cognitive function. The evaluator who conducted these tests was the same evaluator who conducted the measurements pre and post exercise. The evaluators were experts in neuropsychological testing and had relevant academic backgrounds.
Controlled Oral Word Association Test (COWAT)
The COWAT consists of two subtests: semantic fluency and phonemic fluency. In this study, for the semantic fluency task, the participants were asked to generate as many words as possible within 1 min for each of the two categories: “animals” and “items you can buy in a store.” For the phonemic fluency task, the Korean consonants “ㄱ,” “ㅇ,” and “ㅅ” were selected based on previous research [13]. The participants were instructed to produce as many valid words as possible within the time limit. All responses were recorded sequentially, and the inclusion and exclusion criteria for scoring were applied according to prior guidelines [13].
Trail Making Test (TMT)
The TMT is used to assess complex attention. In this study, the participants were asked to connect the numbers 1 to 25 in sequential order, with each number enclosed in a circle. If an error was made, the examiner pointed it out, allowing the participant to correct the error and proceed. The score was recorded as the time (in seconds) taken to complete the task. Longer completion times were considered to indicate lower cognitive function. Time was measured using a stopwatch or a digital timer. All assessments were performed by the same examiner to ensure consistency.
Digit Span Test (DST)
The DST, a standard tool for assessing attention, includes two subcomponents: forward recall and backward recall. For the forward recall task, the participants were asked to repeat a series of digits read aloud by the examiner, beginning with three digits and increasing to a maximum of eight digits, provided each sequence was recalled correctly. The backward recall task began with two digits and increased to a maximum of seven digits under the same conditions. If an error occurred, the same digit length was repeated once. If the participant failed to recall the sequence correctly on two consecutive attempts, the test was terminated at that level.
Exercise Program
The exercise intervention was conducted thrice a week over a 12-week period. Each session lasted 60 min and consisted of a 10-min warm-up, 40-min main exercise, and 10-min cool-down. The main exercise consisted of the following 12 movements, performed in sequence: on-the-spot walking with hand shaking, four-step walking, calf and shoulder raises, wide squats with torso twists and arm extensions, standing torso twists with one arm raised, lunges with arm extensions, wide squats with overhead arm raises, maximum lunges, airplane pose, maximum lunges with one arm raised overhead, lunges followed by knee stretching, and Egyptian pose.
This program was adapted from the Korea Health Promotion Institute’s Senior Muscle and Balance Exercise Completion Program manual [14]. It was modified to suit elderly women with low physical activity levels and a high fall risk. It included components targeting strength, muscular endurance, aerobic capacity, and balance. In accordance with the American College of Sports Medicine (ACSM) guidelines (11th edition) [15], the program was structured into three progressive stages based on the rating of perceived exertion (RPE): Stage 1 (weeks 1-4) involved an RPE of 9-11, Stage 2 (weeks 5-8) involved an RPE of 11-13, and Stage 3 (weeks 9-12) involved an RPE of 13-15.
All exercise sections were conducted under the guidance of exercise professionals, taking into consideration proper exercise and safety for the older participants. In addition, exercise intensity was monitored by assistants.
Statistical analysis
Statistical analyses were performed using SPSS version 29.0 (IBM SPSS Inc., Chicago, IL, USA). Independent samples t-tests were used to assess baseline differences between the exercise and control groups. To analyze the effects of the intervention, a two-way analysis of variance (ANOVA) was conducted to examine the interaction effects between group and time. Where significant interactions were identified, additional independent and paired samples t-tests were performed to assess differences within and between groups. All variables were reported as the means ± standard deviations, and statistical significance was set at p < 0.05.
Results
Changes in the Controlled Oral Word Association Test
Changes in COWAT scores are summarized in <Table 2> . No significant interaction effect between group and time was observed for either semantic fluency or phonemic fluency. However, a significant improvement in semantic fluency was observed in the exercise group (p < 0.05). In contrast, no significant changes were noted in semantic fluency scores in the control group or in phonemic fluency scores in either group.
Changes to the Controlled Oral Word Association Test.
Changes in the Trail Making Test
As shown in <Table 3> , a significant interaction between group and time was noted for TMT scores (p < 0.05). In the exercise group, TMT performance significantly improved after the intervention (p < 0.01); however, no significant changes were observed in the control group.
Changes to the Trail Making Test.
Discussion
This study assessed changes in cognitive function among older adults aged ≥ 65 years following a 12-week structured exercise program by using standardized neuropsychological assessments. The findings revealed significant improvements in semantic fluency, as assessed by the COWAT, and in cognitive processing speed and attention, as assessed by the TMT, in the exercise group. However, no such improvements were noted in the control group.
The COWAT evaluates semantic and phonemic verbal fluency. In this study, the participants were instructed to generate as many words as possible in 1 min for the semantic categories “animals” and “items purchasable at a store” and for the phonemic categories using the Korean consonants “ㄱ,” “ㅇ,” and “ㅅ” [8]. Semantic fluency performance has been linked to frontal lobe atrophy and is considered a sensitive tool for distinguishing between different forms of cognitive impairment, including dementia and Alzheimer’s disease [16]. Moreover, diminished semantic fluency has been linked to the progression from mild cognitive impairment to dementia [17]. An important aspect of the COWAT is the generation of word clusters, which reflect underlying cognitive processes. Semantic clusters typically consist of consecutive words from the same subcategory (e.g., “fish,” “mackerel” or “tiger,” “leopard”), whereas phonemic clusters may contain rhyming words (e.g., gosari [bracken], goguma [sweet potato]), words beginning with the same phoneme (e.g., sagwa [apple], satang [candy]), or homophones (e.g., bam [night], bam [chestnut]) [18]. Troyer et al. [18] reported that clustering primarily reflects temporal lobe-mediated processes, such as lexical and semantic memory retrieval, whereas switching between clusters reflects frontal and frontocortical executive functions, such as cognitive flexibility and set shifting. Studies involving patients with neurological conditions, such as schizophrenia, Huntington’s disease, and Parkinson’s disease, have reported greater impairments in switching than in clustering; however, the opposite trend has been typically noted in Alzheimer’s disease. These distinctions suggest that performance patterns on the COWAT reflect the location and nature of brain dysfunction [19]. Notably, phonemic fluency begins to decline gradually in the 60s, with a marked deterioration observed by the 80s. As this age range coincides with the highest risk of cognitive disorders, such as mild cognitive impairment and Alzheimer’s disease, phonemic fluency is particularly crucial for the early detection of cognitive decline [20]. In this study, a significant improvement was specifically observed in semantic fluency in the exercise group. This finding may be attributed to enhanced functional connectivity between the default mode network (DMN), which is more active during passive or resting states, and the salience network (SN), which facilitates attention to relevant stimuli. Increased connectivity between the frontoparietal network (FPN) and the SN has been associated with memory enhancement [10]; this relationship is consistent with the observed improvements in both semantic fluency and TMT performance in this study.
The TMT is a widely used and validated neuropsychological tool for assessing brain injury and diagnosing neurodegenerative conditions, including Alzheimer’s disease [21]. Poor TMT performance, reflected by longer completion times, indicates impairments in cognitive domains, such as attention, working memory, visual perception, and cognitive flexibility. Although suboptimal TMT performance may also be attributed to physical limitations, such as reduced grip strength or fine motor coordination, the test cannot independently differentiate between cognitive and motor causes of poor performance [21]. Nevertheless, the significant improvements in TMT scores in the exercise group, along with the gains in semantic fluency, suggest that the intervention had a favorable impact on both cognitive and physical domains. Similarly, in a previous study, the TMT exhibited 100% sensitivity and 90% specificity in identifying abnormalities in COWAT performance [22]. There are two primary versions of the TMT: TMT-A, which requires connecting numbers in sequential order (e.g., 1-2-3…25), and TMT-B, which requires alternating between numbers and letters (e.g., 1-ㄱ-2-ㄴ-3…). TMT-A primarily assesses psychomotor speed, visuospatial search, and target-directed tracking [23]. Both versions have demonstrated meaningful correlations in patients with brain injury [24]. In contrast, in our study, no significant differences were observed in the DST scores between the exercise and control groups. The DST, a widely used clinical and research tool, assesses short-term verbal memory and attention [25]. DST performance relies more heavily on the integrity of the left cerebral hemisphere than on that of the right cerebral hemisphere or diffuse brain damage [26]. The lack of significant changes in DST performance in this study may be attributed to the exclusion of individuals with diagnosed dementia or cognitive impairment. Thus, the baseline cognitive health of the participants may have limited the potential for detectable improvements. Moreover, DST performance can vary based on different factors, such as anxiety, task familiarity, educational background, and literacy level. Practice effects may also contribute to performance variability, particularly in individuals with limited prior exposure to such assessments [25].
This study has several limitations. First, the sample exclusively consisted of cognitively healthy older women without diagnosed dementia or cognitive impairment. Future studies should assess the effects of structured exercise programs in populations with clinically diagnosed cognitive disorders. Second, although validated neuropsychological tests were employed, cognitive performance could be influenced by transient factors, such as mood, fatigue, and general physical condition on the day of testing. Future research should consider performing objective, instrument-based assessments of cognitive function to supplement neuropsychological outcomes. Lastly, as all participants were women, the findings may not be generalizable to older men. Future research should include male participants to assess potential sex-based differences in cognitive responses to exercise interventions.
Conclusions
In this study, a 12-week structured exercise program significantly improved semantic fluency, as assessed by the COWAT, and cognitive processing speed and attention, as assessed by the TMT, among older women. No significant changes were observed in semantic fluency in the control group or in DST performance in either group. These findings indicate that regular exercise may serve as an effective nonpharmacological strategy for preserving or enhancing cognitive function in older women, potentially preventing age-related cognitive decline and delaying the onset of neurodegenerative disorders.
In light of these findings, it is essential to develop and implement exercise programs based on comprehensive analyses of diverse factors influencing cognitive health in aging populations. Expanding the application and dissemination of such programs in community settings may be crucial for promoting successful aging and addressing the challenges of a rapidly aging society.
Notes
The authors declare no conflict of interest.