Main Dimensions, Myriad of Assessment Tools and New Approaches for Early Detection of Subjective Cognitive Decline and Mild Cognitive Impairment: A Systematic Review

1. Introduction

The aging of the population and the current increase in the number of people attending neurological and/or neuropsychological consultations due to complaints of the presence of Subjective Cognitive Decline (SCD) warns about the need for stronger research efforts on this condition [1]. Despite the term SCD is not included in international diagnostic manuals such as ICD-11 or DSM-5, over the past decade it has gained significant relevance in describing a condition characterized by a persistent self-perception of reduced cognitive performance beyond what is typical, yet without objective evidence following standardized clinical assessment [1]. Its relevance is due to its potential relationship with subsequent progression to disorders such as Mild Cognitive Impairment (MCI) or as preclinical onset of certain neurodegenerative diseases [1,2,3]. On the other hand, MCI is a complex clinical entity, with several subtypes identified according to their pattern of progression to dementia [4]. This condition can be presented as single-domain amnestic MCI, multidomain amnestic MCI, single-domain non-amnestic MCI, and multidomain non-amnestic MCI [5]. The characteristics of each subtype of MCI may be associated with progression to a specific type of dementia, although this premise is not yet clearly defined [6,7].

Meta-analysis on the risk of dementia and MCI in older people with subjective memory complaints points to a significant predictive value [8]. Thus, it is estimated that within one year, SCD may progress to MCI in 6.6% of cases and to dementia in 2.3%; over four years, this progression increases to 24.4% for MCI and 10.9% for dementia [8]. Given this analysis, it is essential to determine as precisely as possible the subtle changes that may manifest at the cognitive level during the preclinical phases of neurodegenerative conditions. In this context, neuropsychological assessment becomes indispensable in clinical evaluations because of its contribution to identifying existing cognitive deficits, which supports clinical and differential diagnoses [9,10]. Based on such clinical judgment and analysis by complementary laboratory and neuroimaging tests, the professional team will determine a final diagnosis to implement specific treatment [11]. Therefore, in this urgent need to improve detection rates of SCD and/or MCI that would benefit timely interventions, neurocognitive evaluation has been incorporated into the protocols of multidisciplinary teams worldwide [11,12]. Many neuropsychological tests are used in various studies, ranging from screening tests to domain-specific tests. In this respect, groups of experts are developing consensus recommendations to increase the use of brief cognitive assessments (BCAs) in primary care to complement routine medical studies [12,13]. However, there is no consensus on the types of tests to be applied in clinical evaluations, with the choice of tests varying depending on the study [14]. Therefore, this review aims to systematically analyze empirical data on neuropsychological dimensions and tests used during the last fifteen years in various studies addressing the topic of SCD and MCI.

2. Methodology

This study systematically reviews the neuropsychological tests used in studies on SCD and MCI, following the PRISMA method guidelines [15] to ensure its proper execution (Figure 1).

2.1. Systematic Search (Databases, Descriptors, Search Formulas)

Through a systematic search, scientific publications from the past 15 years (2009–2024) on the selected topic were analyzed using the PubMed database as the primary tool. Initially, a search combined the terms “neuropsychological evaluation AND mild cognitive impairment AND subjective cognitive decline,” yielding 518 results as potential sources for analysis. Inclusion and exclusion criteria were then established.

2.2. Inclusion Criteria

-

Empirical research on neuropsychological tools used in the study of subjective cognitive decline and mild cognitive impairment.

-

Studies published in the last 15 years with a specific population focus on individuals aged 60 years or older.

2.3. Exclusion Criteria

-

Studies addressing neuropsychological tests for subjective cognitive decline in other clinical contexts.

-

Research exploring neuropsychological assessments in advanced stages of dementia.

2.4. Flow Chart

Following these criteria, 73 studies were initially selected based on their titles. After reviewing their abstracts, 52 studies were excluded because they did not meet the specific objective of this review. Finally, 21 articles were selected for review because they focused on the study of cognitive performance in individuals with subjective cognitive decline and mild cognitive impairment.

3. Results

Table 1 presents a summary of the most relevant data, which integrated analysis is provided in the following sections.

Study design - The different studies have used longitudinal, follow-up experimental, and cross-sectional descriptive designs. The proposed designs made it possible to describe cognitive performance in participants with subjective cognitive complaints and to determine the presence of MCI, which, depending on its progression, could precede the development of neurodegenerative conditions such as dementia.

Sample - Analyzing the overall data, a total sample of 9,320 participants is included from Western countries (Australia, Central and South Europe, North and South America) and Eastern countries (Korea and China). Sociodemographic variables included gender (with women: men ratio of 3:1), age (average 67.3 years), and years of education (average 10.6 years). All studies included neuropsychological assessments as a critical component in analyzing the clinical profiles of their participants.

Neuropsychological tests - In this review, different authors use neuropsychological screening tests and, in some cases, specific tests or scales for different cognitive domains such as memory, language, perception, visuospatial function, praxis, and executive function, but with no consensus on selection criteria [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36].

Cognitive and behavioral domains - Different cognitive and behavioral domains have been assessed using various tools (see Figure 1). A significant number of studies used executive function tests (25%), followed by those that used screening tests (20%), tests to assess memory processes (14%) and language processes (14%). Finally, other cognitive domains and dimensions have been less addressed in the various studies, namely, self-reports/informant reports - 7%, praxis - 6%, depression/anxiety, and intelligence – 5%, visuospatial processes 3%, and visual perception 1%.

Cognitive components - In turn, specific neuropsychological tests were variably used to determine the performance of the different cognitive components. Of the studies analyzed, the most used screening tests were the MMSE (52%) and the MoCA (13%). The most studied linguistic components were naming and verbal fluency, using naming tests (BNT - 29%) and semantic fluency (24%). Motor and visuospatial processing were assessed to a greater extent through the RCFT (16% and 9%, respectively). The executive processes most frequently assessed were attentional control, working memory, and inhibitory control, using tests such as the TMT A-B (29%), DST (18%), and Stroop test (18%). Memory processes were evaluated with different tests, the most prevalent being the RAVLT (17%).

Authors [Reference] Country	Sample Subjects’ diagnosis (gender ratio) [mean age] {mean years of education}	Dimensions assessed	Tests used
Migliacci et al. [16] Argentina	204 subjects with MCI 51 aMCI (36W:15M) [75.07] 11 naMCI (7W:4M) [69.63] 142 MCImult (104W:38M) [70.58] {-}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, ADAS, CDR, MDRS - WAIS Transitive and intransitive praxis, CDT, RCFT Semantic and fluency test, BNT - RCFT Digits, FAB, TMT A – B, Stroop Test, Wisconsin Test, SMOCT, RAVLT, RBMT
Saunders and Summers [17] Australia	131 subjects (68 W and 63 M): 25 HC [69] {13.5} 32 subjective-MCI [71]{13} 60 amnestic-MCI [71] {13.1} 14 mild AD [76] {12}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	- - WTAR, FSIQ - BNT - - - RAVLT, PAL -
Abbate et al. [18] Italy	119 subjects with MCI (74 W:45 M) [77.38] {9.27}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE - - RCFT VFT, PNT - - RCPM, TMT, DST, DCT PRT Informant reports on cognitive functioning (structured interview)
van Harten et al. [19] Netherlands	132 participants with SCC (56 W:76 M) [61.4] {6}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE - - - Naming category fluency - - TMT A-B, DST VAT, RAVLT -
Toledo et al. [20] USA	522 subjects (253 W:269 M) 307 CN subjects (138 W:169 M) [73.9] {-} 71 subjects SCC (25 W:46 M) [71.6] {-} 51 subjects executive SCI (21 W:30 M) [77.3] {-} 66 subjects memory SCI (49 W:17 M) [75] {-} 27 subjects multi-domain SCI (20 W:7 M) [78] {-}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, ADAS - - - - - - - - -
Seo et al. [21] Korea	265 participants (178 W:79 M) 188 CN subjects (120 W:60 M) [71.94] {9.69} 77 subjects pre-DCL (58 W:19 M) [72.64] {9.64}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, SNSB GDS - RCFT CPFT, K-BNT - RCFT TMT A-B, DST, Stroop test, SVLT SMCQ (informant report)
Verfaillie et al. [22] Netherlands	233 participants SCD (107 W: 125 M) [62.82] {5.32}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE GDS - - Fluency Animals - - TMT A-B, DST, Stroop test RAVLT, VAT -
Fogarty et al. [23] England	55 participants (35 W:20 M) 23 subjects mild AD (9 W:14 M) [73.95] {15.56} 32 adult control subjects (26 W:6 M) [69.84] {13.96}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, MoCA GDS - - - - - - - BRIEF-A
Bae et al. [24] South Korea	1442 participants (-) [-] {-} 1088 HC subjects (-) [-] {-} 354 SCC (-) [-] {-}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, K-DRS - - - - - - - - -
Rios et al. [25] Mexico	69 subjects MCI (54 W:15 M) [71.79] {2.76}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, CCT YDS WAIS RCF BNT, semantic fluency - - TMT, Wisconsin Test, RCPM GBMV SCS (informant report)
Viviano et al. [26] USA, Netherlands	83 participants (51 W:32 M) 35 adults with SCI (22 W:13 M) [68.5] {-} 48 adults without SCI (29 W:19 M) [67.08] {-}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, BFI GDS, BDI - - - - - - WMS -
Valech et al. [27] Spain	68 normal subjects (46 W:22 M) 52 HC (33 W:19 M) [63.87] {11.96} 16 pre-AD (13 W and 3 M) [66.5] {9.56}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE HADS - - BNT, BDAE, Semantic fluency VOSP - TMT A, Stroop test MAT, FCSRT-IR SCD-Q
Czornik et al. [28] Austria	54 subjects with SCD and MCI (28 W:26 M) [66.8] {12.5} 12 SCD 14 aMCI 28 naMCI	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, NTBV - - - - - - - WMT SIMS, SRSI
Pérez et al. [29] Spain	195 participants SCD (121 W:74 M) [65.71] {14.94}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	- - WAIS - Letter semantic, verbal fluency - - TMT A-B, RSCS-BADS, AI-SKT - -
Kim et al. [30] Korea	1442 participants (886 W:556 M) [≥65 years] 1088 HC subjects (642 W:446 M) {5.66} 354 SCC subjects (244 W:110 M) {3.33}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE-KC - - - - - - K-DRS - -
Hao et al. [31] China	615 subjects SCD plus (378 W:228 M) [-] {-}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MoCA - - CDT Fluency Test - - TMT B AVLT-H SCD-Q
Esmaeili et al. [32] -	62 subjects (-) [-] {-} 17 SCC subjects 30 amnestic-MCI subjects 15 HC subjects	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	- - - - - - - ANT - -
Garrido et al. [33] Spain	136 subjects (67 W:59 M) 28 young adults with SCC (17 W:11 M) [21] {-} 37 young adults without SCC (16 W:11 M) [23] {-} 32 older adults with SCC (18 W:14 M) [63] {-} 39 older adults without SCC (16 W:23 M) [65] {-}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE - - RCFT Phonological fluency, Semantic fluency - - TMT A-B, Stroop Test, DST, IGT FCSRT MFE-30
Li et al. [34] China	201 subjects (105 W and 96 M) 95 AD [68.23] {10.68} 106 FTLD [63.24] {9.93}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	MMSE, MoCA HAMD-21 - - - - - FBI - NPI
Oliver et al. [35] USA	3019 healthy older adults 831 with SCD (635 W:196 M) 2188 without SCD (1660 W:528 M) [73.6] {14.74}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	- - - - BNT NC PM, Line Orientation DST, SDMT, Stroop test WMSR, EBS, WLMR -
Morrison et al. [36] Canada	273 subjects 97 with SCD (36 W:61 M) 176 without SCD (90 W:86 M) [72.97] {16.66}	Screening scales Depression/anxiety scales Intelligence Praxis Language Visual perception Visuospatial Executive function Memory Self / Informant report	ADAS-13, MMSE, MoCA - - - - - - - - -

Abbreviations: W: women. M: men. SCC: subjective cognitive complaints. SCD: subjective cognitive decline. SCI: subtle cognitive impairment. AD: Alzheimer’s disease FTLD: Frontotemporal lobar degeneration. HC: healthy control. NC: Normal Control. CN: cognitively normal. MCI: mild cognitive impairment. aMCI: amnestic mild cognitive impairment; naMCI: nonamnestic mild cognitive impairment. MCImult: mild cognitive impairment multidomain. MMSE: Mini-mental Scale Examination. MoCA: Montreal Cognitive Assessment. ADAS: Alzheimer’s Disease Assesment Scale. CDR: Clinical Dementia Rating. MDRS: Mattis Dementia Rating Scale. WAIS: Wechsler Adult Intelligence Scale. RCFT: Rey–Osterrieth complex figure test. BNT: Boston Naming Test. CDT: Clock Drawing Test. FAB: Frontal Assessment Battery. TMT (A-B): Trail Making Test. SMOCT: short orientation-memory-concentration test of cognitive impairment, RAVLT: Rey Auditory Verbal Learning Test. RBMT: Rivermead Behavioral Memory Test. WTAR: Wechsler Test of Adult Reading. FSIQ: Estimated full-scale intelligence quotient. PAL: Paired Associates Learning. VFT: Verbal Fluency Test. PNT: Picture-naming Test. RCPM: Raven’s colored progressive matrices. PRT: Prose recall test. DST: Digit span test. DCT: Digit cancellation test. VAT: Visual Association Test. SNSB: Seoul Neuropsychological Screening Battery. GDS: Geriatric Depression Scale. CPFT: Categorical and phonemic fluency tests. K-BNT: Korean version of the Boston Naming Test. SVLT: Seoul Verbal Learning Test. SMCQ: Subjective Memory Complaints Questionnaire. BRIEF-A: behavior rating inventory of executive function-adult version. K-DRS: Subscale of the Korean version of Matts Dementia Rating Scale. CCT: Cerad Cognitive Test. YDS: Yesavage Depression Scale. GBMV: Grober and Buschke Memory Verbal. SCS: Subjective Complaint Scale. BFI: Big Five Inventory. BDI: Beck Depression Inventory. WMS: Weschler Memory Scale. HADS: Hospital Anxiety and Depression Scale. BDAE: Boston Diagnostic Aphasia Examination-III Edition. VOSP: Visual Object and Space Perception Battery. MAT: Memory Alteration Test. FCSRT-IR: Free and Cued Selective Reminding Test. SCD-Q: Subjective Cognitive Decline Questionnaire. NTBV: Neuropsychological Test Battery Vienna. WMT: Word Memory test. SIMS: Structured Inventory of Malingered Symptomatology. SRSI: Self-Report Symptom Inventory. RSCS-BADS: Rule Shift Cards subtest. AI-SKT: Automatic inhibition subtest. MMSE-KC: Mini-mental Mental State Examination Korean version. K-DRS: Korean rating scale. AVLT-H: Auditory Verbal Learning Test Hua Shan. ANT: The attention network test. IGT: Iowa Gambling Task. FCSRT: Free and Cued Selective Reminding Test. MFE-30: Memory Failures of Everyday Questionnaire. HAMD-21: Hamilton Depression scale 21. FBI: Frontal Behavioral Inventory. NPI: Neuropsychiatric Inventory Questionnaire. NC: Number Comparison. PM: Progressive Matrices. SDMT: Symbol Digital Modalities Test. WMSR: Wechsler Memory Scale-Revised. EBS: East Boston Story, WLMR: Word List Memory Recall and Recognition.

Figure 1. Neuropsychological dimensions in subjective cognitive decline and mild cognitive impairment. In order of magnitude (in percentage): Executive function (25%), Screening scales (20%), Memory (14%), Language (14%), Self/Informant report (7%), Praxis (6%), Depression and anxiety (5%), Intelligence (5%), Visuospatial (3%), Visual perception (1%).

Figure 1. Neuropsychological dimensions in subjective cognitive decline and mild cognitive impairment. In order of magnitude (in percentage): Executive function (25%), Screening scales (20%), Memory (14%), Language (14%), Self/Informant report (7%), Praxis (6%), Depression and anxiety (5%), Intelligence (5%), Visuospatial (3%), Visual perception (1%).

Figure 2. Neuropsychological assessment tools in subjective cognitive decline and mild cognitive impairment. In order of magnitude (in percentage): MMSE (52%), TMT A-B (29%), BNT (29%), semantic and fluency test (24%), Stroop test (18%), DST (18%), RAVLT (17%), MoCA (13%).

Figure 2. Neuropsychological assessment tools in subjective cognitive decline and mild cognitive impairment. In order of magnitude (in percentage): MMSE (52%), TMT A-B (29%), BNT (29%), semantic and fluency test (24%), Stroop test (18%), DST (18%), RAVLT (17%), MoCA (13%).

4. Discussion

This review of studies describing the characteristics of subjective cognitive deficits and MCI highlights the significant heterogeneity in the methodology used. It exposes the complexity of clinical assessment at the prodromal phases of neurodegenerative diseases but also depicts the main dimensions, myriads of assessment tools, and new approaches for early detection of Subjective Cognitive Complaints and MCI according to authors in the field [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36].

Since preclinical stages of dementia are associated with subtle changes in various cognitive processes beyond memory which were initially associated with neurodegenerative diseases, early detection is crucial in the clinical setting for interventions [9]. The use of screening tests seems to lack sufficient validity when determining prodromal signs of dementia. There are screening tools that may be indicative but not conclusive. However, some of the studies in this review [20,23,24,34,36] primarily use the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), and the Alzheimer’s Disease Assessment Scale–Cognitive (ADAS-cog). Some authors considered that the MMSE may be accurate for detecting Alzheimer’s disease; however, they recommended using the º for detecting MCI, as it is a more sensitive test for measuring early cognitive changes [39,40]. In contrast to this idea, other authors [14] argued that tests such as the MMSE, among other screening tools, have not proven to be sufficiently sensitive for assessment in Primary Care. They further discuss that other factors, such as administration time or individual circumstances (educational level, sensory problems, and others) may interfere with applying basic tests, failing to identify specific cognitive issues. Kueper et al. [41], on the other hand, suggested that the ADAS-cog is not an optimal tool for detecting subtle pre-dementia changes and that it should be used in parallel with other tests that more accurately assess memory processes, executive functions, and daily living activities.

The use of specific neurocognitive tests is essential in clinical assessment. Thus, the use of neuropsychological tests as part of care protocols for patients with SCD and MCI has become a necessary tool for early diagnosis of potential neurodegenerative conditions such as dementia. However, finding tools sensitive enough to assess neurocognitive processes is complex and requires extensive analysis [1,10,37,38]. In the present review, of the seventeen studies that used screening tests [16,18,19,20,21,22,23,24,26,27,28,29,30,31,33,34,36], half of them (9/17) applied other complementary tests that addressed different cognitive domains [16,18,19,21,22,25,27,31,33]. These studies provide arguments that the best approach to determine potential cognitive changes in preclinical stages and their possible progression to neurodegenerative diseases involves administering screening tests, complemented with specific neurocognitive tests and formal informant reports, providing the clinician with sufficient information to make a much more accurate diagnosis [42].

Assessing different cognitive domains presents a challenge in determining early cognitive decline in neurodegenerative diseases. Although studies include several specific cognitive tests in this review, there is no consensus on which ones are essential for their application and which key cognitive processes should be assessed. This is a critical issue, since the current experts’ recommendations refer to the need to introduce BCAs in primary care systems to fast early detection and intervention, but are also warn about barriers that healthcare systems may face when introducing new novel cognitive assessment tools [12]. The selection of a specific protocol may be related to possible cognitive profiles associated with different types of MCI or profiles associated with the classification of various types of dementia [43]. Specifically, all the studies in this review used scales that assess memory processes, which are a central element in evaluating all research; hence, the classification of MCI: amnestic, non-amnestic, and multidomain. In this regard, measures of delayed recall are considered the best neuropsychological predictors of the conversion of MCI to Alzheimer’s disease [44]. On the other hand, most studies also focused on assessing various executive processes as potential early predictors of MCI. The literature suggests that assessing executive functions such as working memory, attentional control, planning, and others., could be a critical factor in identifying possible pathological signs in the preclinical stages of dementia [45,46].

Interestingly, self or informant reports and the presence of neuropsychiatric symptoms (depression and anxiety) emerged as two potentially relevant domains to be considered, too. Seven studies included scales to assess emotional symptoms (depression or anxiety) [21,22,23,25,26,27,34]. Assessing the emotional domain in older adults with cognitive complaints is crucial; the presence of depressive and anxious symptoms in patients with subjective cognitive complaints is of clinical interest because of their potential association with cognitive impairment and progression to neurodegenerative diseases. The coexistence of depression and/or anxiety with subjective cognitive decline is associated with an increased risk of developing dementia; early identification of these symptoms is a crucial component in understanding the subtle emotional changes that may also precede these diseases [2,46,47,48]. On the other hand, the use of self-report scales and informant reports seems to complement the clinical assessment significantly. Some reviewed studies used this tool in their methodology [18,21,23,25,27,28,31,33,34]. Literature also supports the need to inevitably include these tools in any cognitive impairment evaluation, providing valuable information on the impact on daily activities that may be perceived by the individual and/or their informants [49,50,51].

Finally, behavioral and personality changes received some interest in the reviewed studies. Li’s study [34] used scales to assess potential neuropsychiatric and personality changes in its participants; whereas the other two authors, Caselli et al. [52] and Terracciano et al. [53] argued that behavioral changes may be an early signal during the transitional phases between MCI and certain dementias, such as Alzheimer’s disease.

Thus, the great complexity and heterogeneity the different studies face when analyzing cognitive performance in patients with subjective cognitive complaints and MCI can be observed. This highlights the urgent need for more evidence regarding the tools to be used in the early stages of dementia, understanding their reliability and validity, and the multiple variables that may interfere with the results of a standardized and formal evaluation [54]. Furthermore, studies need to accurately determine MCI characteristics and emphasize qualitative rather than quantitative analysis of the neuropsychological tests applied [6].

5. Conclusions

Clinical attention to subjective cognitive complaints and the mechanisms used to objectify them through the application of a precise neuropsychological evaluation remains challenging for mental health professionals. The heterogeneity of individual characteristics has hindered the availability of tools sensitive enough to detect the initial, often subtle, changes in cognitive performance during the prodromal stages of cognitive decline in older adults.

When analyzing the methodology of various studies in the field, there is no consensus on the neurocognitive tests that should be applied to this type of clinical population. The different studies agree on the need to use certain specific screening tools and specific assessment tests on executive, linguistic, and memory components, which here appeared as the main targeted dimensions and could serve the BCAs. However, the lack of homogeneity in the brief or long protocols used highlights the still uncertain path regarding the clinical tools that can determine the possible subtle changes that occur in the preclinical stages of neurodegenerative conditions.

Any evaluation protocol should also be complemented with scales or questionnaires that assess emotional aspects and personality. There is sufficient evidence showing that some neurodegenerative conditions can be characterized by behavioral and mood changes, sometimes isolated from cognitive issues, and these may be part of the evolution of the incipient clinical condition. Similarly, formal self-report questionnaires, supplemented by those of informants, can provide valuable information to determine the impact of cognitive complaints on daily activities and provide greater precision when assessing individuals’ functionality.

Finally, when addressing the complexity and limitations of neuropsychological assessment in the preclinical stages of dementia, it is essential to conduct studies that precisely unify the criteria regarding clinical characteristics and the potential protocols to be used to manage SCD and MCI. Additionally, it is crucial not to overlook the complex task involved in qualitative clinical assessment in any study of neuropsychological performance, which should be the subject of future research.