Introduction
The aging population is increasing worldwide, increasing the risk of neurological and cognitive disorders [2]. Given that brain pathology progresses before symptoms appear in patients with dementia, there are cognitive interventions to delay cognitive decline not only in older adults with mild cognitive impairment (MCI) or dementia, but also in older adults with healthy cognitive status [6]. Cognitive interventions can improve cognitive functions such as executive functions, working memory, episodic memory, processing speed, language, spatial skills, planning, organization, and divided attention [7]. It seems necessary to conduct a meta-analysis study to investigate whether computerized and traditional cognitive interventions have an effect on improving the cognitive functions of healthy older people, those with MCI or Alzheimer's disease, in order to take a step towards guiding health professionals and psychologists in the field of geriatric health. Therefore, the present study aims to review the effectiveness of computerized vs traditional cognitive interventions on cognitive functions of healthy older people and those with MCI or Alzheimer's disease in Iran using a meta-analysis method.

Methods
All studies published from 2012 to 2023 were searched using the keywords cognitive rehabilitation, cognitive stimulation, cognitive training, software, computer, computer games, cognitive functions, executive functions, attention, memory, elderly, older adults, aging, aged, mild cognitive impairment, and alzheimer's disease in the databases Web of Science, Scopus, PubMed, Scientific Information Database (SID), Comprehensive Humanities Portal, and IranDoc. Theses and articles were included to reduce publication bias. Grey literature was searched using Google Scholar search engines. The inclusion criteria for the systematic review were based on the PICO-SD framework. Two authors independently performed initial screening of titles and abstracts to avoid selection bias. Removal of duplicate studies and full-text review to identify relevant studies were first done by the first author and then reviewed by the corresponding author. Any disagreement was resolved by consensus. 
Data were analyzed using CMA software, version 2. Hedges' g index was used to calculate the effect size of the studies. Standardized mean differences (SMDs) were calculated as Hedges' g and considering 95% confidence intervals (CI) for the difference in outcomes between the experimental and control groups after the intervention. Pooling of SMDs across studies was performed using a random-effects model. Cochran's Q-statistic and I2 index were used to examine the heterogeneity of effect sizes. A mixed-effects model was used for subgroup analysis. Funnel plot, Duval and Tweedie’s trim-and-fill method, and the fail-safe N test were used to examine publication bias.

Results
The initial search yielded 712 studies. According to the inclusion and exclusion criteria, 26 studies were finally selected for the review; 14 studies used computerized cognitive interventions (software, games, and virtual reality) and 12 studies used traditional cognitive interventions (pencil and paper). Eleven studies examined older people with normal cognitive status (n=406), eight studies examined older people with Alzheimer's disease (n=240), and seven studies examined older people with MCI (n=202). The analysis included a total of 848 participants. The number of intervention sessions ranged from 8 to 24 sessions and the duration of each session ranged from 30 to 120 minutes.
Using the random-effects model, the total effect size (g) of computerized and traditional cognitive interventions on cognitive functions was 1.57 (95% CI, 1.33%, 1.81%; P<0.001). Therefore, it can be said that computerized and traditional cognitive interventions are effective in improving the cognitive functions of the elderly. Figure 1 shows the forest plot of the effectiveness of these interventions in the experimental groups compared to the control group. Subgroup analysis showed that the combined effect size was 1.75 for studies used computerized cognitive interventions (95% CI, 1.41%, 2.09%) and 1.28 for the studies used traditional cognitive interventions (95% CI, 0.98%, 1.57%). The Q-statistic for this difference was 4.21 with 1 degree of freedom and P=0.04. Therefore, it can be said that computerized cognitive interventions are slightly more effective than traditional cognitive interventions in improving cognitive functions of the elderly.



In the funnel plot, there was appropriate symmetry in the distribution of studies, and no study was observed close to the x-axis. The use of trim-and-fill method for sensitivity analysis showed that the observed/adjusted effect size was 1.30 and the present study did not require other studies to be completed. The fail-safe N test results showed that there should be 3692 studies with non-significant findings for the overall effectiveness of computerized or traditional cognitive interventions in improving cognitive functions of the elderly to be insignificant, which seems unlikely.

Conclusion
The present systematic review and meta-analysis showed that both computerized and traditional cognitive interventions have a positive and high impact on improving cognitive functions of Iranian older adults. Therefore, cognitive interventions can be used to reduce cognitive deficits and improve cognitive functions in these people. There were some articles that did not report the gender of samples and the average duration of the intervention sessions, which prevented the study of the effect of the moderating variables of gender and intervention duration on the cognitive functions of the elderly. Most articles focused on short-term cognitive outcomes, and few studies reported follow-up data. Therefore, we did not have sufficient data to assess the durability of the effects of cognitive interventions. Also, since all articles were experimental, there was a clear lack of randomized controlled trial studies. Therefore, more comprehensive randomized controlled trials are needed to determine the impact of cognitive interventions on cognitive functions of Iranian older adults, especially in the long term.

Ethical Considerations

Compliance with ethical guidelines
This article is a systematic review that was not conducted on human or animal samples. Accordingly, there was no need for an ethics code and all ethical rules were observed in the research.

Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for profit sectors.

Authors' contributions
All authors contributed equally to the conception and design of the study, data collection and analysis, interpretation of the results, and drafting of the manuscript. Each author approved the final version of the manuscript for submission.

Conflicts of interest
The authors declared no conflict of interest.



 

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