This systematic review was conducted to identify the cognitive tests that have been validated in older Iranian adults and to evaluate the evidence for their accuracy. The initial section of the discussion provides a brief description of the diagnostic accuracy measures of the investigated instruments, categorizing them based on their administration time. Subsequently, the discussion delves into the applicability of these instruments in identifying dementia and MCI in different clinical settings.
Instruments with Shorter Assessment Time (< 10 min)
Clock Drawing Test (CDT)
The CDT has recently gained popularity as a straightforward, efficient, and acceptable tool for screening cognitive disorders. It assesses a range of cognitive domains that may be impaired early in neurocognitive disorders, such as executive functioning and visuo-constructive skills(23). It is especially useful in patients with marked verbal impairment or aphasia because it does not depend much on verbal abilities. It is also minimally influenced by language and cultural background(24). However, the CDT does not assess episodic memory; therefore, it is often combined with other tests(25). Additionally, research findings have indicated that individuals with no literacy skills demonstrate notably poorer performance on this assessment compared to those who are literate(26). Among Persian-speaking Iranian elderly individuals, the CDT utilizing Shulman's six-point scoring method demonstrated a sensitivity of 90% and specificity of 73% when employing a cutoff point of ≤ 3 for detecting dementia. The PPV was 69%, while the NPV was 91%.(27). The calculated LR + was 3.33, the LR- was 0.13, and the DOR was 25.61.
Mini-Cog
The Mini-Cog has emerged as a valuable brief screening tool for detecting cognitive impairments in primary care settings. This assessment integrates a 3-item recall component with an evaluation of a clock drawing task, encompassing a wide array of cognitive functions such as memory, attention, and executive function. The recall test is scored on a scale of 0 to 3, while the clock drawing task is assigned a score of either 0 or 2. These individual scores are then aggregated to generate a total score that ranges from 0 to 5(28). Various studies have reported differing sensitivity levels (76–99%) and specificity (89–93%) for the Mini-Cog in detecting dementia. However, its accuracy in detecting cases of MCI is not as reliable.(29). Furthermore, it should be noted that the Mini-Cog may have limited utility in individuals with low levels of education or illiteracy. A recent study conducted in Iran, focusing on older adults admitted to hospitals, discovered that a significant proportion of Persian-speaking seniors with limited education and normal cognitive functioning faced difficulties in completing the clock drawing task of the Mini-Cog test(30).
The optimal cutoff point for the Persian version of the Mini-Cog for detecting dementia was determined to be 2, with a sensitivity of 88% and a relatively modest specificity of 62.8% (31). The LR + was calculated as 2.31, the negative LR- was 0.19, and the DOR was 12.15.
The Short Portable Mental Status Questionnaire (SPMSQ)
The SPMSQ evaluates orientation, remote memory, mental control, and attention. However, it does not include a specific assessment of short-term memory, nor does it encompass items related to right hemisphere, occipital, or frontal lobe impairments. The score ranges from 0 to 10 based on the number of incorrect answers(32). The Persian version validated a cutoff point of 4 for illiterate elderly patients (sensitivity 86.4%, specificity 88.2%, LR + 7.32, LR- 0.15, DOR 48.8) and 3 for literate patients (sensitivity 83%, specificity 93.7%, LR + 13.17, and LR- 0.18, DOR 73.16), showing acceptable accuracy for detecting cognitive impairment in both the illiterate and literate groups. However, the SPMSQ is more accurate in identifying moderate and severe dementia than MCI(33).
A Quick Test of Cognitive Speed (AQT)
The AQT is a cognitive assessment tool designed to evaluate visual-verbal processing speed. Originally developed for primary care settings, it measures the speed of perception and overall cognitive processing. It can be applied to various languages and cultures and individuals with low education levels(34). The AQT has demonstrated high sensitivity (87–98%) but low specificity (11–59%) for detecting dementia (DOR 1.88-39) and MCI (DOR 2.35–31.6) in Iranian seniors(35).
The Quick Mild Cognitive Impairment (Qmci) Screen
The Qmci screen is a reliable and brief tool specifically designed to distinguish between individuals with MCI and normal controls. It assesses cognitive functioning across six subtests, covering orientation, working memory, semantic memory, visuospatial ability, and episodic memory(36). The Persian version of the Qmci demonstrates fair accuracy in identifying MCI and mild dementia, with an area under the curve (AUC) of 0.87. At an optimal cutoff score of < 53/100, it exhibits a sensitivity of 79%, specificity of 80%, LR + of 3.95, LR- of 0.26, and DOR of 15.19). This test accurately identifies moderate to severe dementia, with a sensitivity of 88%, specificity of 90%, LR + of 8.8, LR- of 0.13, and DOR of 67.69 at an optimal cutoff of < 38/100(37).
Rowland Universal Dementia Assessment (RUDAS)
The RUDAS is a cognitive assessment tool suitable for multicultural settings and individuals with limited literacy. It evaluates body part recognition, visuospatial function, reasoning, and memory(38) .In the Persian version of the RUDAS, a cutoff score of 20 demonstrates a sensitivity of 86%, specificity of 79%, LR + of 8.9, LR- of 0.02, and DOR of 24.05 for detecting dementia(21).
Picture-Based Memory Impairment Screen (PMIS)
The PMIS is a concise screening tool that involves four pictures from distinct categories to evaluate delayed free and cued recall. Each picture freely recalled by the individual receives two points, while pictures recalled with cues are awarded one point, resulting in a score range of 0 to 8. Notably, the PMIS does not necessitate the ability to write, exhibits minimal susceptibility to educational and literacy levels, and can be easily administered by trained non-specialists. However, it does not encompass an assessment of executive function and demonstrates limited sensitivity in detecting early-stage dementia and MCI(39). The PMIS has undergone validation in older Iranian adults, exhibiting a sensitivity of 60%, specificity of 91%, PPV of 63%, and NPV of 90% for detecting dementia. These metrics were established using a cutoff score of 5(40). An LR + of 6.66 and an LR- of 0.43 were calculated for this study.
Abbreviated Mental Test Score (AMTS): The AMTS was originally developed and validated in 1972 as a preliminary screening tool designed to identify cognitive impairment in elderly patients. This concise assessment consists of ten items that evaluate intact short- and long-term memory, attention, and orientation abilities(41). Notably, the AMTS is freely accessible and can be administered quickly and easily, making it suitable for individuals with limited literacy skills. Furthermore, it does not necessitate the use of writing utensils or paper, rendering it appropriate for individuals with visual or physical impairments(41, 42). However, one of its limitations lies in the requirement for two individuals to be present at the bedside during the assessment for the recognition question. Depending on the chosen cutoff score, the sensitivity and specificity of the AMTS in detecting cognitive impairment have been reported to range from 81–96% and 75–86%, respectively(43, 44). Nevertheless, evidence indicates that the AMTS exhibits a ceiling effect and is less sensitive to milder cognitive deficits(45). The validation study of the Persian version of the AMTS among older Iranians revealed a total Cronbach's α coefficient of 0.90. A score of 6 or lower indicates dementia with a sensitivity of 99% and specificity of 85%. The corresponding LR + was 6.60, and the LR- was 0.011, indicating relatively strong diagnostic evidence. In this Persian adaptation, AMTS scores exhibited positive correlations with educational level and male sex, while displaying a negative correlation with age(46).
Instruments with moderate assessment time (10–15 min)
Mini–Mental State Examination (MMSE)
The MMSE is the most frequently used screening tool for providing an overall measure of cognitive impairment in community, research, and clinical practice. This scale assesses several cognitive domains, with scores ranging from 0 to 30, with higher scores indicating better cognitive function(47). The MMSE has shown low sensitivity for MCI, does not perform well in assessing executive functions and has limiting floor and ceiling effects(48). Four studies have investigated the psychometric features of the Persian version of the MMSE in Iranian older adults(49–52). The pooled sensitivity, specificity, DOR, LR+, and LR- for the optimal cutoff scores of 21 to 22 for diagnosing dementia were 0.97, 0.87, 242, 7.69, and 0.03, respectively, indicating a high accuracy; however, the accuracy of the MMSE for detecting MCI in Iranian seniors was low, with an LR + of 2.24 and an LR- of 0.4. Age and education levels had significant correlations with MMSE scores in most of the studies reviewed.
Modified Mini-Mental State Examination (3MS)
The 3MS is an enhanced version of the MMSE that adds four tasks on long-term memory, abstract thinking, category fluency, and delayed recall. It has a broader score range of 0–100 and maintains the brevity, ease of administration, and objective scoring of the MMSE. However, it is also affected by culture, language, age, physical disability, and education levels(53). The Persian version of the 3MS had an optimal cutoff score of 78 for detecting dementia with 98% sensitivity and 81% specificity(54). The LRs were 8.9 for positive test results (LR+) and 0.02 for negative test results (LR-), suggesting a higher accuracy for diagnosing dementia than the MMSE.
Instruments with Longer Assessment Time (> 15 Min)
Montreal Cognitive Assessment (MoCA)
The MoCA is a 30-point cognitive screening tool designed to address the shortcomings of the MMSE in detecting MCI and mild dementia. It evaluates diverse cognitive domains, including attention, executive function/visuospatial ability, conceptual thinking, free recall, language, and orientation(55). Healthcare professionals specializing in cognitive assessment are recommended to interpret the results of the MoCA due to its complexity and sensitivity to cognitive impairments(56). Rashedi et al. established a cutoff score of 22 for the Persian version of the MoCA for identifying MCI, which demonstrated a sensitivity of 86.4%, specificity of 70%, PPV of 81%, NPV of 77.8%, LR + of 2.88, and LR- of 0.19, indicating the MoCA’s satisfactory diagnostic accuracy for detecting MCI. Additionally, the study introduced a cutoff score of 20 for identifying dementia, which exhibited a remarkable sensitivity of 99%, specificity of 94.9%, PPV of 96.6%, NPV of 94.9%, LR + of 9.98, and LR- of 0.05, showing convincing diagnostic accuracy(51).
Addenbrooke’s Cognitive Examination (ACE)-III: The ACE—III is an extended cognitive screening scale developed to overcome the shortcomings of the MMSE with additional items that assess executive functioning, memory, and language in greater depth. It has demonstrated the ability to differentiate individuals with MCI, allows for tracking the progression of cognitive deficits, and shows some utility in distinguishing Alzheimer’s disease from frontotemporal dementia(57). Nevertheless, ACE-III scores are influenced by age, level of education, and intelligence(58). The total score of ACE-III is based on a maximum of 100, with higher scores indicating better cognitive functioning(57). The Persian version of ACE-III had a high accuracy for diagnosing MCI at a cutoff score of 84 (sensitivity: 93%, specificity: 91%, LR + 10.33, LR- 0.07) and dementia at a cutoff score of 78 (sensitivity: 100%, specificity: 96%, LR + 10.42, LR- 0.2)(59). Additionally, another study reported a cutoff score of 75 for detecting dementia (sensitivity 99%, specificity 95%, LR + 19.8, and LR- 0.01), providing convincing diagnostic accuracy (22).
Persian Test of Elderly for Assessment of Cognition and Executive Function (PEACE): The PEACE is a culturally adapted cognitive screening test proposed to assess the cognitive efficiency of both illiterate and literate older Iranian adults. It consists of 14 items, each of which represents a specific cognitive function, with a maximum score of 91. The 14 items are orientation, praxis, attention and concentration, calculation, memory, similarity, abstract thinking, general information, language, judgment, gnosis, planning (sequencing), problem-solving, and animal naming. A cutoff score of 67.5 was chosen for the optimal diagnosis of dementia by PEACE (sensitivity: 75.8%, specificity: 97.4%, LR + 29.1, LR- 0.24). However, adequate diagnostic accuracy to detect MCI was not shown by the test(60).
Rey Auditory Verbal Learning Test (RAVLT)
The RAVLT is a five-trial verbal learning and memory test with a delayed recognition component. It assesses the ability to encode, consolidate, store, and retrieve verbal information. While the test is sensitive to verbal learning and recall, it is influenced by age, education, and intelligence(61). The RAVLT was validated in Iranian older adults, showing convergent validity with the logical subtest of the Wechsler Memory Scale. It had 89% sensitivity and 81% specificity for detecting dementia(62). The calculated LR + was 4.68, indicating its utility in identifying dementia, while the LR- was 1.08, suggesting a moderate effect on ruling out the presence of dementia.
Detection of Cognitive Impairment in Primary Care and Community Settings
In primary care and community settings (for example, community-based epidemiological studies), a concise tool must be used to assess cognitive function in older adults and identify those who may require further evaluation. The critical requirements for such tools are ease of use, minimal training requirements, and quick administration(56). In light of the study's findings, we propose dividing the elderly population into two groups based on their educational level and recommend suitable cognitive screening tools for each group.
Older adults with more than six years of education
For older adults with education beyond the elementary level, we recommend the utilization of the Qmci and RUDAS as primary care screening tools. These instruments effectively assess a broad range of cognitive domains, demonstrate acceptable diagnostic accuracy (with DORs of 67.69 and 24.05, respectively), and can be administered within a brief duration of ten minutes or less. Notably, several systematic reviews have provided robust evidence supporting the diagnostic performance of Qmci and RUDAS in detecting cognitive impairment within primary care settings(63, 64).
Illiterate and low-educated older adults
For older adults with limited or no literacy, we recommend using the AMTS, SPMSQ, and PMIS in descending order of diagnostic accuracy. All three tests can be administered swiftly, within ten minutes or less. Among these scales, the AMTS demonstrates remarkable proficiency in identifying cases of dementia (with a DOR of 660). However, the SPMSQ does not encompass assessment of episodic short-term memory, which is typically the initial cognitive domain affected in amnestic mild cognitive impairment and Alzheimer's disease. It has been evaluated among illiterate Iranian older adults and has shown acceptable diagnostic accuracy (with DORs of 48.8 and 73.16 for illiterate and literate individuals, respectively)(33). The PMIS evaluates a narrower range of cognitive domains and has demonstrated slightly lower diagnostic accuracy (with a DOR of 15.48) than the abovementioned tests.
Within the context of primary care, it is imperative to recognize that the MMSE stands out as the most extensively researched scale for dementia detection in the elderly population of Iran. The results of this meta-analysis indicate that the MMSE shows high diagnostic accuracy for dementia. However, it should be noted that there was significant heterogeneity among the included studies, which complicates the interpretation of the analysis results and the formulation of recommendations based on the pooled estimates. Additionally, there are essential factors to consider that may discourage the use of the MMSE in primary care settings. The MMSE and its modified version, the 3MS, are relatively lengthy assessments, which may limit their practicality in primary care settings where time constraints are common. Moreover, these tests may exhibit educational bias, disproportionately benefiting individuals with higher levels of education. Recognizing that these limitations could affect the equitable assessment and diagnosis of individuals with diverse educational backgrounds is crucial. Regarding the other cognitive tests evaluated in this study, namely, MoCA, ACE-III, PEACE, and RAVLT, their administration time is considerably long, rendering them impractical for routine use in primary care. Additionally, these tests may pose challenges in terms of interpretation, further limiting their suitability for primary care settings.
Detection of Cognitive Impairment in Specialized settings
Within specialized care settings, such as memory clinics or clinical trials, it is imperative to comprehensively evaluate various cognitive domains to identify even subtle impairments in cognitive function and evaluate treatment response. Therefore, there is a need for cognitive assessments that exhibit high diagnostic precision in detecting MCI and the early stages of dementia(65). Among the cognitive screening tests evaluated in older Iranian adults, ACE-III had the highest diagnostic accuracy for both MCI (DOR 147.57) and dementia (DOR 1980). Consequently, for older adults with more than six years of formal education, we recommend the utilization of ACE-III. Conversely, the PEACE emerges as a viable choice for individuals with limited literacy. This test has demonstrated notable diagnostic accuracy within this population (DOR: 121.45)(60).