With the increasing proportion of elderly individuals within the population, CI emerges as a significant public health concern, posing threats to the independence of older adults and exerting profound challenges on the social security and healthcare systems [1]. According to MoCA test examination of the studied population, the estimated prevalence of CI in this study was 50.2% with 37.7% who had MCI, and 12.5% were demented. This figure is consistent with an Egyptian study that estimated the prevalence of CI in community-dwelling elderly as 51.4% [24]. The prevalence of CI worldwide varies widely. In a systematic review (including 80 studies), the estimated prevalence of CI ranged between 5.1 and 41% with a median of 19.0% [25]. These variations can be attributed to various factors including the study settings, demographic characteristics of the population, cultural differences, and variations in the assessment tools used for screening. These factors collectively contribute to variations in the definition and categorization of mental and neurocognitive disorders, thereby influencing the wide range of CI prevalence reported [26].

The prevalence of MCI in Egypt was estimated as 32% by Amer et al. [27]. Another study also found the prevalence to be 34.2 and 44.3% of the elderly men and women, respectively [15]. That was consistent with the result of the current study that the prevalence of MCI was 37.7%. The higher prevalence of CI, both MCI and dementia, within the Egyptian population can potentially be attributed to the significant proportion of illiteracy among Egyptian elderly individuals, accounting for approximately 56.5% [28]. In the present study, illiterate individuals or those with lower educational levels represented 58.5% of the studied population that further emphasizes the association between educational attainment and cognitive health.

By investigation of the type of CI using the Hachinski ischemic score, in the present study, the degenerative type was the most common type among cognitively impaired subjects followed by mixed type then the vascular type. This is consistent with the classification of dementia in most literatures where the most common type of neurodegenerative dementia was Alzheimer and then vascular dementia [29, 30].

The extent and patterns of impairment across the range of cognitive domains are not yet well established so we used a newly developed validated tool named Ain Shams Cognitive Assessment (ASCA) tool that assesses specific cognitive domain functions among cognitively impaired subjects [18]. For easier comparison with other literature, we classified the cognitive domains into the most common domains classified by DSM-5 (learning and memory, complex attention, executive function, language, perceptual motor function) [19]. We found that the highest proportion of test impairment was for the figure copy and recall of Bender-Gestalt test (94%), naming (83%), and word recognition test (80%) which primarily assess visuospatial and memory functions respectively. These results suggest that patients were particularly impaired in visuospatial and memory domains. This is consistent with the type of cognitive impairment tested above where the most common type of impairment was the degenerative type. This is due to the common predominance of memory impairments in neurodegenerative-related cognitive impairment, compared with predominance of attention/executive in vascular-related impairment [31].

By examination of the distribution of patterns of impairment among CI participants, it was very diverse, and most of them were impaired on at least one cognitive domain with a very few participants who had cognitive performance at or above average expectations. This is consistent with previous study [32]. Patterns of impairment across cognitive domains were as follows: 94.1% for visuospatial function, 88.1% for working memory and for language and semantic memory functions,75% for attention, 69.5% for executive functions, 30% for learning and verbal memory, 25.5% for judgment, and 12.7% for abstraction. In another study, the prevalence of specific domain affection was as follows: 31.5% for visuospatial function, 41.2% for language, 41.7% for executive function, 42.2% for learning and memory, and 48.8% for complex attention [32]. Those lower prevalence rates than the current study may be attributed to the different data presentation method as they assessed the pattern of domain affection in the total study population, while in the current study, we assessed it among the cognitively impaired subjects only. Therefore, the proportion of impairment was higher in the current study. Furthermore, the distribution of the pattern was different, which could be attributed to different risk factors. Their study was conducted among hemodialysis patients who have vascular risk factors for vascular dementia which was reflected on higher affection of attention and executive functions.

The diversity in cognitive performance and varying rates of cognitive decline have been documented to undergo alterations in relation to a range of factors, including demographic characteristics, educational background, lifestyle choices, physical well-being, social engagement, and economic resources [33]. Testing the relationship between cognitive function and socioeconomic domains in the current study revealed that CI (MCI or dementia) was significantly associated with low educational level, unemployment, low income, limited computer use, and bad sanitary condition. In the same context, a recent study revealed that older adults who reported lower perceived income, lower educational attainment, compromised physical and mental health, and limited access to physical and social resources were found to have a higher likelihood of CI [34]. Moreover, it is important to note that the influence of these sociodemographic characteristics on cognitive function is not uniform, as they can interact with one another, giving rise to unique patterns of cognitive performance [35].

By examination, in the effect of SES level on performance across different cognitive domains, we found that there was significant association between SES level and impairment in the following cognitive sub-domains (episodic verbal memory, language and semantic memory, processing speed, and visuospatial functions). Impairment of those sub-domains was higher in low SES subjects in comparison with high and medium SES subjects with significant difference. Although impairment in the working spatial function was the most common sub-domain impairment among the three groups, there was no statistically significant difference between them. The observed distribution of cognitive domain impairment can be explained by exposure to persistent chronic stressors that have been linked to reductions in hippocampal and amygdala volume, as well as atypical activity in the prefrontal cortex. These brain regions play a vital role in various cognitive functions, including memory, emotion processing, executive functions, and social behavior [36].

A substantial body of literature demonstrates a consistent and independent association between socioeconomic status and cognitive function in later stages of life [33,34,35]. This was confirmed in the present study where there was a highly significant association between cognitive function and SES level. The mechanism by which SES impacts cognitive impairment is thought to be through the building and preservation of brain reserve capacity [35]. The concept of cognitive reserve highlights the brain’s remarkable capacity for flexibility and adaptability, enabling it to actively counteract the impact of age- or disease-related alterations within its networks [37].

It is widely accepted that low SES is one of the risk factors for CI in older adults. Individuals with lower SES often have limited health literacy due to their lower levels of education. Additionally, they are less likely to receive health advice and have reduced motivation to undergo CI screening, which is compounded by limited access to health resources. This economic disparity also results in reduced social participation, as low SES individuals may lack the time and energy to engage in socially enriching activities that can expand their cognitive reserve and buffer the risk of CI. Thus, low SES populations are more susceptible to CI [38].

In contrast, individuals from higher socioeconomic groups are typically more advantaged with regards to health. Their good working and living conditions and greater access to healthcare knowledge and medical technology, resulting from their educational background, occupational status, and income, make them less susceptible to health injuries and better able to prevent cognitive decline. Furthermore, they are more inclined towards a healthy lifestyle and social network, which can help delay cognitive decline [39]. Even when cognitive decline occurs, those with higher SES have a better chance of detecting the condition early and correcting adverse factors to avoid further deterioration of cognitive function [40]. Therefore, there is an urgent need to prioritize efforts aimed at enhancing cognitive function and preventing the progression from MCI to dementia, particularly among older adults who are at higher risk, including those from low SES backgrounds. Ensuring improved access to healthcare services becomes a critical focus in addressing the needs of this vulnerable population.

This study has some limitations with generalizability as the sample size was a convenient sample, and also, the design was a cross-sectional study that could not assess the actual causal effect of different socioeconomic indicators (education, work stat, computer use, income, etc.) and impairment in specific cognitive domain. So, more longitudinal studies with larger sample sizes focusing on investigating the underlying risk factors for CI and its inequity among Egyptian elderly in various regions in Egypt are needed.