The Comparison of the Effectiveness of Morning and Evening Exercise on Cognitive Performance and Depression in Older Adults with Type 2 Diabetes

Depression in old age is considered the second leading cause of disability after physical illnesses. Depression in older adults is often associated with cognitive impairment. It is therefore important to consider the physical, emotional, and cognitive changes that occur during this stage of life. Physical activity may also exert a protective effect against cognitive decline in older adults. Therefore, this study aimed to determine the effects of morning and evening aerobic exercise on cognitive performance and depression in older adults with type 2 diabetes. This was a quasi-experimental study using a pretest-posttest design with a control group. The statistical population consisted of all older women with medical records at the Shahrekord Diabetes Association. The sample included 45 older women aged 55 to 65 years selected through convenience sampling method and based on the inclusion and exclusion criteria. They were randomly assigned to morning exercise, evening exercise and control groups. The intervention consisted of a 12-week aerobic exercise program with an intensity of 60-70% of maximum heart rate reserve. The tools used in this research include the Beck Depression questionnaire, and Montreal Cognitive Assessment (MoCA). Data were analyzed using ANCOVA in SPSS-22. The results indicated that both morning and evening aerobic exercise significantly affected blood glucose levels, cognitive function, and depression in older adults, with greater benefits observed in the evening exercise group. Maintaining physical health, such as controlling diabetes through regular physical activity, may help improve social relationships and reduce the risk of depression. Moreover, increased blood flow to the brain, higher levels of brain hormones, reduced inflammation and stress, and enhanced social interaction may contribute to improved cognitive performance in older adults.
EXTENDED ABSTRACT
 Introduction
The rapid advancement of technology, improvements in medical science, and enhanced healthcare conditions have led to a decline in mortality rates, an increase in life expectancy, and ultimately a growing trend of aging populations in the coming years. This demographic shift has accelerated the global transition toward an aging population. During the later stages of life, individuals often face various physical and psychological health challenges, including diabetes, cognitive decline, and increased depression, which contribute to reduced life satisfaction and greater dependency. Consequently, maintaining mental health in modern society is a critical issue that yields lasting benefits for individuals, families, and communities. Physical exercise plays a fundamental role in preserving health and enhancing the quality of life. Engaging in physical activity at any time is beneficial, although certain periods may be more effective than others. Considering the significance of mental health and the existing gap in research on interventions for cognitive and emotional disorders in this stage of life, this study seeks to examine two hypotheses: (1) Aerobic exercise can influence psychological indicators such as depression and cognitive function; and (2) the timing of exercise (morning vs. evening) may produce different effects on cognitive performance and depression.
Method
This study employed a quasi-experimental design with a pre-test and post-test approach, including a control group. The study population consisted of all women with medical records at the Diabetes Association of Shahrekord. Sampling was conducted through a public call for participation among women diagnosed with type 2 diabetes who met the eligibility criteria, using a convenience sampling method. Inclusion criteria were: (1) a diagnosis of type 2 diabetes for more than five years, and (2) an age range of 55–65 years. Exclusion criteria included: (1) musculoskeletal injury, (2) inability to perform the exercise program, and (3) presence of a specific medical condition that contraindicated exercise. A total of 45 women aged 55–65 years (mean age: 60.07 ± 5.07 years) were randomly assigned to three groups: morning exercise (15 participants), evening exercise (15 participants), and control (15 participants). Before and after the exercise period, all participants completed the Beck Depression Inventory and the Montreal Cognitive Assessment. The 12-week training program consisted of three sessions per week, each lasting 30 minutes, involving moderate-intensity walking and running (at 60–70% of maximum heart rate reserve), including warm-up and cool-down phases. Finally, the collected data from the questionnaires were analyzed using descriptive statistics (mean, standard deviation, etc.) and inferential statistics (ANCOVA) in SPSS version 26.
Results
Prior to data analysis, it was determined that the distribution of scores for all variables was normal, and the assumption of homogeneity of variances was confirmed. Additionally, the assumption of homogeneity of regression coefficients was examined, with results indicating that the F values were not significant at the .05 level for any variable. After verifying the assumptions of covariance analysis, the research hypotheses were evaluated using both multivariate and univariate analyses of covariance. To examine the impact of morning and evening aerobic exercise on cognitive performance and depression, Multivariate Analysis of Covariance (MANCOVA) was employed. The results of the Box’s M test were assessed to ensure no violation of the assumption of equality of covariance matrices, confirming that this assumption was met. As shown in the following table, the p values for all tests indicated a significant difference in cognitive performance (Montreal Cognitive Assessment) and depression scores (Beck Depression Inventory) between the pretest and posttest across the three groups: morning exercise, evening exercise, and control. Thus, physical exercise was effective in influencing cognitive performance and depression, supporting the primary hypothesis that aerobic exercise significantly affects these psychological variables.The results of the Bonferroni test indicate that, for the variables of depression and cognitive performance (as measured by the Montreal Cognitive Assessment), there is a significant difference between both experimental groups (morning and evening exercise) and the control group (p < .001). However, the difference between the morning and evening exercise groups was not statistically significant (p > .05). This means that both intervention methods, compared to the control group, had a significant effect in reducing depression and improving cognitive performance. Additionally, evening aerobic exercise appeared to have a greater impact on both variables.
Conclusion
The later stages of life are characterized by various physical, social, and psychological changes. One of these changes is the transition away from previous occupational roles, leading to a reduction in job-related responsibilities and, consequently, a decline in social interactions. Another significant characteristic is the experience of loneliness, particularly in cases where an individual has experienced the loss of friends, peers, or long-time acquaintances, increasing feelings of depression over time. Some individuals gradually withdraw from social life, while society may also marginalize them, reinforcing a sense of meaninglessness and deepening depression. Physical changes also occur, such as the gradual deterioration of cortical cells in the brain. Furthermore, the overall physical health of an individual plays a crucial role in their ability to participate in social activities, as health status becomes a fundamental determinant of social engagement at this stage of life. Findings from the present study indicate that aerobic exercise can enhance cognitive performance and reduce depression. The timing of physical activity may depend on specific objectives, while individual conditions and preferences may also influence the choice of exercise time. If individuals face time constraints or have particular preferences, it is essential to tailor exercise routines accordingly to
ensure alignment with their needs and lifestyles. Overall, the results demonstrate that aerobic exercise program, regardless of time of day, had a positive effect on depression and cognitive performance in women with type 2 diabetes.
Ethical Consideration
Ethical Code
This study was approved by the Ethics Committee of Yazd University (IR.YAZD.REC.1402.044) and registered in the Iranian Registry of Clinical Trials (IRCT) under the identifier IRCT20181212041935N1.
Financial Support
This research was financially supported by the Iranian National Science Foundation (INSF) under approval code 4013082.
Authors’ Contributions
A.M.A: Conceptualization, Methodology, Project administration, Data Curation, Writing - Review & Editing; Z.H.F: Conceptualization, validation, Writing - Review & Editing; Z.H: Data Curation, Visualization; Sh.H.GH: Validation, Formal analysis, data Curation.
Conflict of Interest
The authors declare no conflicts of interest
Acknowledgments
We sincerely appreciate the financial support provided by INSF, and extend our deepest gratitude to all participants for their valuable contributions to this study.
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