Comparison of Dual Task Training Versus Aerobics Training in Improving Cognition in Healthy Elderly Population

Background Cognitive impairments, particularly in old age, are pervasive and occur because of both normal and pathological senescence. Engaging in some routine bodily activities combined with activities that stimulate cognitive skills appears beneficial in increasing cognitive resistance to degenerative processes of the brain. Dual-task training (DTT) by combining motor and cognitive activities causes improvement, particularly in executive function, working memory and divided attention, whereas aerobic exercise training (AET) plays an important role in improving executive function, attention, and memory. In this study, we attempted to compare the efficiency of DTT versus AT in improving cognitive function in healthy older individuals. Methods Forty healthy older adults between 60 and 70 years of age who met the inclusion criteria participated in this study. They were randomly split into two groups A and B. Group A (64.05±3.17 years) received DTT three times a week, whereas group B (65.50±3.44 years) received AT five times a week. Both training programs were conducted for six weeks. Cognitive function was assessed using Trail Making Test (TMT)-A, TMT-B, and Montreal Cognitive Assessment (MoCA). The assessment was done at baseline (first day of intervention), on completion of the third week, and again at the end of the training session i.e., the sixth week. The Chi-square test and the student's paired and unpaired t-tests were used for statistical analysis with a level of significance P<0.05. Discussion and result Betterment in cognitive functions was evident after six weeks of DTT and AET. Post-intervention improvements were noted in TMT-A, TMT-B, and MoCA scores in both groups A and B (P>0.0001). However, the difference between the pre and post-intervention scores was greater for group A compared to group B indicative of remarkable improvements in cognitive function in group A. Conclusion The current study demonstrated that both DTT and AET are notably efficient in improving cognitive function in a healthy elderly population. However, in comparison, DTT was significantly more effective than AET (P<0.05). This shows that six weeks of DTT is effective in improving cognitive function and slowing age-associated cognitive decline in older adults.


Introduction
India's geriatric population is on the rise [1]. Around 10 crore Indians are more than 60 years of age. The average lifespan of the Indian population has expanded from 32 years in 1947 to 54 years in 1980 and 70. 19 years in 2022 [2,3]. As per the World Health Organization (WHO), the global population aged 60 and more is anticipated to increase from 900 million in 2015 to 2000 million by 2050 [4]. Approximately 18 million people worldwide are said to be dealing with age-related mental health concerns. As stated by the WHO, this figure will increase to 34 million by 2025 [2].
Aging-related degenerative processes affect brain structure and function. Cognitive decline is practically ubiquitous among elderly people, and it worsens as they become older [5]. Memory loss, deterioration in executive function (EF), and poorer motoric speed and precision, are some of the cognitive deficits that people would almost certainly encounter as they get older [6]. Cognitive function (CF) is a mental process in humans that includes attention, perception, reasoning, knowledge, and memory [6][7][8][9]. Additionally, When intellectually demanding tasks are paired with multimodal physical exercises, performing a cognitive and motor activity (dual task) at the same time appears particularly beneficial for improving CF in healthy elderly people [5]. In brain plasticity, physical training (PT) and cognitive training (CT) may perform distinct but complementary roles [16]. PT boosts the brain's metabolic activity, but this gain can only be used if there is a need for it. Challenging the brain and its particular cells in the context of a specific cognitive activity generates a such type of demand. It is plausible to believe that multimodal training slows down the senescence of the brain, as evidenced by improved cognitive functioning and postponement in cognitive decline, through this mechanism [17]. In other words, PT improves brain metabolism and plasticity, whereas CT exploits and reinforces the improved metabolism and directs brain plasticity by increasing mental demands. If the processes underlying gains in CF differ in PT and CT, then integrating both of them in one intervention might increase the advantages over a single training mode [16].
Aerobic activities increase physical activity levels by increasing the proficiency of the circulatory system to deliver oxygen and the ability or efficacy with which skeletal muscles use it [18]. Several studies have shown that aerobic exercise, which involves the usage of O2 and the sustained action of large muscle groups, can boost EF, processing speed, attention, and memory in healthy elderly people [19].
According to human research trials, aerobic exercise training (AET) has the biggest influence on spatial memory, WM, and executive attention. Other studies have found that physically active individuals perform better in visual figure recognition, spatial memory, and attentional control (i.e., the Eriksen flanker task) [20]. Increased cardiovascular endurance and circulation in the brain lead to better utilization of oxygen and glucose, increased neurogenesis stimulation, and increased synaptic interconnections [12]. There is a link between physical fitness and cognitive performance in women aged 70-80 years and AET improves verbal and spatial memory as well as verbal-auditory learning [12,21].
Previous research studies related to cognitive aspects of aging have found that as people age, their brain structure and function change, involved in EF and the attention system, as well as WM areas [5,11,12]. As a result, it's vital to find and apply efficient ideas and tactics that might aid in the retention and even enhancement of cognitive abilities in the elderly [13].

Materials And Methods
After receiving approval from the Institutional Ethics Committee of Datta Meghe Institute of Medical Sciences (DMIMS) (Deemed to be University), Wardha, India (approval number: DMIMS[DU]/IEC/2021/367), the study was conducted in the neuro-physiotherapy outpatient department (OPD) of Acharya Vinoba Bhave Rural Hospital, Wardha, Maharashtra, India. Informed consent was obtained, arbitrary data was gathered, and a preliminary evaluation was done to determine whether or not the individuals met the inclusion and exclusion criteria. The inclusion criteria were that the participants had to be of either gender and between the ages of 60-70, not taking any medicines known to impair cognitive performance (such as benzodiazepines, antidepressants, or other central nervous system agents) [22], without a known CNS disease, such as thyroid disorders, multiple sclerosis, Parkinson's disease, stroke, severe hypertension (systolic blood pressure greater than 180, diastolic blood pressure greater than 110), or diabetes, six-minute walk distance 592-630 meters for male and 511-558 for female [23], be able to understand and follow instructions, and be willing to participate in the study. People who had any central or peripheral nervous system involvement, severe cognitive impairments, Mini-Mental State Examination (MMSE) score below 26, musculoskeletal disorders such as rheumatoid arthritis, life expectancy less than three months, severe auditory and visual defects, and those who were currently registered in another clinical trial were all excluded from the study. The selected participants were explained the objectives and methods of the study. Using the sequentially numbered, opaque, sealed envelope (SNOSE) technique, the participants were randomly assigned to either group A or group B by simple random sampling. The primary researcher and a physiotherapy intern conducted the randomization and allocation. The study's enrollment, intervention, and evaluation timeline followed the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) 2013 guidelines. A flowchart of the study procedure is depicted in Figure 1.

Outcome measures
A physiotherapy undergraduate student who was aware of the study but blinded to the intervention evaluated the following outcome measures before and after the intervention.

Trail Making Test (TMT) A and B
TMT is a neuropsychological test that combines visual scanning and working memory. TMT is broken into two parts: TMT-A (rote memory or WM) and TMT-B (EF). Each of the two parts consists of 25 circles scattered across a sheet of paper. Part A contains circles numbered from 1-25, and the individual should connect the numbers by drawing lines in ascending order. Part B contains circles with both numbers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) and letters (A-L); the individual must draw lines to connect the circles in ascending order, with the added challenge of alternating between the numbers and letters (for example, 1-A-2-B-3-C, etc.). Individuals must be encouraged to connect the circles as rapidly as feasible. The test results are recorded as the time required for completing the test [24].

Montreal Cognitive Assessment (MoCA)
MoCA is used to assess general CF. It examines cognitive processes such as: "memory," "language," "EFs," "visuospatial abilities," "calculation," "abstraction," "attention," and "concentration." It has a total score of 30, with higher numbers indicating better CF. A normal score is regarded to be 26 or higher. A score of 19 to 25 is an indicator of mild cognitive impairment (MCI) [25,26].

Interventions
TMT-A, TMT-B, and MoCA tests were carried out before and after the intervention. Subjects in Group A executed cognitive-motor DTT in which they performed cognitive activities alongside motor ones while subjects in Group B performed AT.

Group A: DTT
In the cognitive-motor DTT, participants performed cognitive activities in conjunction with motor activities. There was evidence of improvement in cognition within four weeks of the intervention [22], whereas another study concluded positive results within six weeks of the intervention [27]. The participants were given 45-minutes training sessions, three times a week for six weeks, taking into account the data given in Table 1.

TABLE 1: Description of the studies including population and duration of intervention that were used as a reference while designing an intervention protocol for the present study
The participants, while seated, performed actions like dragging the foot, and placing it on floor markers (marked from 1 to 5), and with each repetition, they said any sentence or words related to a topic given by the therapist., such as "family," "children," "weather," etc. (Figure 2).  While standing, with alternate hip flexion-extension, and abduction-adduction, the subjects named the objects shown in the picture as presented by the therapist (Figure 4).  With spot marching, participants recited multiplication tables of 11,12,13,14 backward in the first, second, third, and fourth weeks, respectively ( Figure 6). Other activities done were: walking forward while listening to sounds in the surroundings such as fan, chirping of birds, rumbling of leaves, etc.; while walking by evading obstacles, the subjects were given any scenario and were told to think, analyze, and tell what will they do; while walking backward, the subjects had to draw a clock and were told to put in all the numbers and set the time to 4 past 15; While tandem walking, they recited a tongue twister (Figure 7). The subjects performed a dance step and spoke aloud the names of the months in a year. While climbing stairs, a song was played, and then suddenly stopped. The subjects were asked to continue singing from that line. In another exercise, before ascending stairs, a specific sequence of tactile stimuli (different textures) was presented to the subjects. Later, after completing the descent, they were asked to identify and state the sequence of the textures presented. While ascending stairs backwards, subjects executed serial 7 subtractions, forward digit span, and backward digit span. The subjects also performed orientation exercises in a room with the help of a map. The subjects followed the instructions and described something that they could find in a convenience store, house, room, etc.

Group B: AT
The training program was based on the WHO's 2010 Global Recommendations On Physical Activity For Health and the ACSM guidelines [19,28]. Literature is divided over the duration of AT required to obtain a positive outcome. One study reported a positive outcome within six weeks [29]. Participants underwent AT for 45 min, five days per week. The participant's maximal and resting heart rates determined the training intensity. The warm-up consisted of stretching exercises and walking for 5-10 minutes. The active phase involved the treadmill, bicycle, and walking exercises ( Figure 8). Participants were encouraged to walk quickly in a single uninterrupted bout (45 minutes for five days); intensity and duration were initiated in a stepwise manner [13,19]. During the first week, the subjects walked for 30 minutes at 9-10 on the Borg Rating of Perceived Exertion Scale (BRPES) contemplated as mild intensity. In the second week, the duration was raised to 45 min, the intensity being similar to the previous one. Throughout the rest of the session (four weeks), they kept the 45-minute workout and raised the intensity of the exercise to a modest-vigorous effort, which corresponds to 12-14 on the BRPES. Participants were taught how to use the BRPES and keep track of their exercise intensity and frequency in a diary [19]. The cool-down period was of 10-minute duration.

Statistical analysis
The level of significance for the statistical analysis was set at p<0.05, and descriptive and inferential statistics were performed using the Chi-square test, student paired and unpaired t-tests, and the software used for the analysis was IBM SPSS Statistics for Windows, Version 27.0 (Released 2020; IBM Corp., Armonk, New York, United States) and GraphPad Prism 7.0 (GraphPad Software, San Diego, California, United States). The student t-test was used to compare groups A (DTT) and B (AT) to determine which training protocol was most efficient in improving cognitive function. Within groups A and B, a paired t-test was used to compare pre and post-scores. An unpaired t-test was used to compare the post-mean difference scores between groups A and B.

Results
The distribution of subjects according to baseline characteristics is shown in Table 2. The mean age (P<0.17), sex (P<0.74), hand dominance (P<1.00), and education (P<0.95) of the two groups were very marginally different.

Baseline Characteristics
Group   Tables 3, 4 and Figures 9, 10 show statistical evidence for the impact of treatment on TMT-A scores in groups A and B at three weeks and six weeks compared with baseline. Table 3 and Figure 9 depict a statistical analysis of the TMT-A scores and the significant value of comparison between the groups at baseline, third week, and sixth week using student's paired t-test. In groups A and B, there was a considerable decrease in the duration required to complete the test, indicating improvement in CF following treatment compared to before treatment (P<0.0001). Table 4 and Figure 10 shows a comparison of the mean difference in TMT A scores in groups A and B at three weeks and six weeks using student's unpaired t-test. When the mean difference in duration required to complete the test was compared between the two groups at three weeks and six weeks, it was observed that there was no significant difference at three weeks (P<0.16); however, the significant difference was noted at six weeks, i.e., following completion of the intervention (P<0.0001) and the DTT group performed better than the AT group (P<0.0001), showing a significant difference between both but DTT > AT     Tables 5, 6 and Figures 11, 12 show statistical evidence for the impact of treatment on TMT-B scores in groups A and B at three weeks and six weeks compared with baseline. Table 5 and Figure 11 depicts a statistical analysis of the TMT-B scores and the significant value of comparison between the groups at baseline, third week, and sixth week using student's paired t-test. In groups A and B, there was a considerable decrease in the duration required to complete the test, indicating improvement in CF following treatment compared to before treatment (P<0.0001). Table 6 and Figure 12 shows a comparison of the mean difference in TMT B scores in groups A and B at three weeks and six weeks using student's unpaired t-test. When the mean difference in duration required to complete the test was compared between the two groups at three weeks and six weeks, it was observed that there was a significant difference both at three weeks (P<0.029) and six weeks, i.e., following completion of the intervention (P<0.0001) and the DTT group performed better than the AT group (P<0.0001), showing a significant difference between both but DTT > AT.     Tables 7, 8 and Figures 13, 14 show statistical evidence for the impact of treatment on MoCA scores in groups A and B at three weeks and six weeks compared with baseline. Table 7 and Figure 13 depict a statistical analysis of the MoCA scores and the significant value of comparison between the groups at baseline, third week, and sixth week using student's paired t-test. In groups A and B, there was a considerable increase in the MoCA scores, indicating improvement in CF following treatment compared to before treatment (P<0.0001). Table 8 and Figure 14 depict the comparison of the mean difference in MoCA scores in groups A and B at three weeks and six weeks using student's unpaired t-test. When the mean difference in MoCA scores was compared between the two groups at three weeks and six weeks, it was observed that there was a significant difference both at three weeks (P<0.001) and six weeks, i.e., following completion of the intervention (P<0.0001) and the DTT group performed better than the AT group (P<0.0001), showing a significant difference between both but DTT > AT.

Discussion
Cognition encompasses a range of mental functions that enable us to perceive, process, and interact with our surroundings [11,30]. As a result, having healthy CF is critical for human existence. Processing speed and memory are two CFs proven to decline with aging. The number of people with poorer cognitive abilities is expected to rise in the coming years, mandating the establishment of comprehensive cognitive improvement interventions that aid in optimizing cognitive reserve and resistance to neurodegeneration [11]. The current study attempts to determine the inclusion of which training strategy, either DTT or AT, would be more effective in improving CF in a healthy elderly population. TMT-A, TMT-B, and MoCA were used as outcome measures to assess cognition.
DTT has been proven in numerous trials to be useful in improving cognition in the older population [5,[13][14][15]19,22,[31][32][33][34] and many studies have shown the effectiveness of AT on cognition in the elderly population [4,13,19,20,[35][36][37]. There is a lack of enough evidence to show the importance of TMT in assessing CF. Very few studies have shown how DTT improves MoCA scores [38][39][40] and TMT scores [41,42], especially in the healthy elderly population. Similarly, very few studies have shown how AT improved MoCA scores [29,43,44] and TMT scores [19]. Few studies have been conducted to test the efficacy of DTT versus AT in improving CF in healthy elderly people, mostly outside India [45]. , and a significant difference was found in the two groups in the third and sixth week post intervention. These results reveal that both groups improved significantly after treatment, although group A improved the most.
MoCA is used to assess general CF. It examines cognitive processes such as memory, language, executive functions, visuospatial abilities, calculation, abstraction, attention, and concentration. It has a total score of 30, with higher numbers indicating better CF. A normal score is considered 26 or higher. MCI is characterized by a score of 19 to 25. MoCA is associated with higher sensitivity (90%) and specificity (87%) in the detection of cognitive decline or MCI [25]. The mean score increased from 24.90, 26.05 to 27.40 for group A and 24.75, 25.35 to 26.15 for group B at baseline, third week, and sixth week, respectively, after six weeks of training. By comparing the mean difference of MOCA in the 3rd and 6th week, mean values increased from 0.36 to 0.60 respectively in Group A. However, in Group B, the mean difference was the same in the third and sixth week, i.e., 0.59, and a significant difference was found in the two groups in the third and sixth week post intervention. Thus, significant improvement was seen post treatment in CF in both the groups, but more in group A. A study by Park showed that the MOCA scores changed from 22.53 ± 2.15 prior to intervention to 23.23 ± 2.24 post intervention in the DTT group after eight weeks of training [40].
The ability of a person to accomplish two activities simultaneously, such as cognitive and motor tasks, is referred to as DT [31,46]. Given the necessity of dealing with DT on a routine basis (as most routine tasks need the concurrent performance of the motor and cognitive tasks), as well as observed deterioration in performance as the individual ages, it appears evident that including the DT approach in training programs could be effective in increasing elderly folk's ability to walk and postural control while dealing with CF or addressing DT situations [32,47]. Even though divided attention diminishes with age, it is needed for several routine activities [15]. Compared with control groups, who are trained only for walking, DTT administered for six weeks improve memory in elderly individuals with a history of falls [33,48]. It is effective in improving general CF [17,49], EF [50,51], processing speed [26,52], visual, and verbal episodic memory, and sustained visual attention [5,26].
Aerobic activities such as cycling, walking, and running are included in treatment plans to help people with CF, particularly the elderly [11]. According to neuroimaging studies, AT increases volume in both gray and white matter over six months, notably in the prefrontal cortex (PFC), which is more sensitive to the impact of aging. In EF, the PFC is hypothesized to play a key role [36]. Aging affects the hippocampus and PFC, which can impair episodic memory, WM, attention encoding, and retrieval. As stated by Jardim et.al., "Daily physical activity improves brain structure and function, particularly in elderly people, with alterations occurring at the molecular/cellular, brain structure/function, mental states, and higher order behavioral levels, all of which contribute to the mitigation of functional losses" [5]. Di Liegro et.al. stated that "endurance activities such as long-duration aerobic activity (running) increase the circulating growth factors like insulin-like growth factor 1 (IGF-1) as well as neurotrophins like brain-derived neurotrophic factor (BDNF), both of which have an impact on the brain throughout development and in maturity" [35].
In older people, higher aerobic fitness levels were linked to the preservation of left and right hippocampal volume as well as better performance on a spatial memory test, demonstrating a three-part relationship between aerobic fitness, hippocampus volume, and memory functions [20,36]. According to meta-analyses, AET can improve a myriad of CFs in healthy elderly individuals, including executive skills, episodic memory, processing speed, and selective attention [13,22].
The study could be expanded in the future to include an equal number of males and females and compare the results of males and females, studying the efficacy of the two interventions in relation to one another while taking into account the different cognitive domains and running for a longer duration to determine the precise length of time required to improve CF using either technique. Limitations of the study were that only healthy people were included in it, the study was conducted on a small population, and unequal numbers of men and women were recruited.
A brief description of some of the studies including population, intervention, outcome measures, and findings is given in Table 9.