臨床症状

Subjective cognitive decline (SCD) is a state in which individuals complain of cognitive impairment; however, they perform normally on standard neuropsychological tests. SCD is considered a diagnostic entity of risk for mild cognitive impairment (MCI) and dementia. SCD and MCI correspond to stages 2 and 3, respectively, in the clinical staging of the continuum of the Alzheimer's disease (AD). Portability of APOEε4 allele increases AD's risk, and its interaction with SCD might raise the cognitive impairment's risk. Herein, we aimed to explore the relationship between SCD, MCI and APOEε4 status in Mexican-mestizo older adults.

84 Mexican-mestizo older adults (86.9% females) were included after consent was obtained (protocol INNN_139/23). Three comparable groups by age (69.37±6.51 y.o.) and years of schooling (13.46±2.92) were formed, n = 28/group, as follows: participants with normal cognition (NC), SCD and MCI. The MoCA and the Cognitive Complaint Questionnaire (CCQ) cut point scores at enrollment were used to classify the groups. APOE genotyping was assessed by allelic discrimination and SPSS was used for statistical analysis.

Significant differences were observed in the cognitive performance between the NC and MCI groups (27.36±1.47 vs. 22.21± 2.06, p <0.001). Regarding the cognitive complaint, NC group showed the lowest score, followed by the DCS and MCI groups (11.71± 6.54, 28.18± 5.75 and 26.66± 9.89, p <0.001) (Table 1). The distribution of APOE genotype and allele frequencies of the studied sample was within Hardy-Weinberg equilibrium. Comparison of APOEε4 allele frequency was different between NC vs. SCD and MCI (p <0.005), while SCD and MCI groups behaved similarly (p >0.05). Being carrier of APOEε4 increased the risk of SCD (OR=5.17, CI95%=1.06-25.13, p = 0.04) and MCI (OR=6.60, CI95%=1.39-31.34, p = 0.02), compared to the NC group (Figure 1).

An association between SCD, MCI and APOEε4 was identified in our sample of mestizo-Mexican older adults; of note, no differences were found for APOEε4 allele between the SCD and MCI groups. The risk of portability of APOEe4 was comparable in SCD and MCI, highlighting SCD as a clinical risk prediction entity in the AD continuum. The relevance of SCD should be further studied in the prevention of dementia by improving early detection.