Clinical Manifestations.

Abstract

Subjective Cognitive Decline (SCD) is a condition characterized by consistent cognitive complaints in cognitively unimpaired (CU) individuals and is associated with progressive cognitive impairment, especially in the context of Alzheimer's disease (AD). We aimed to show the study protocol and the preliminary results of the Brazilian Subjective Cognitive Decline (BRASCODE) Cohort. CU individuals with > 65 years old and cognitive complaints were recruited. Exclusion criteria were previous diagnosis of dementia, uncontrolled neuropsychiatric/clinical illness, or cerebrovascular disease. The assessment was performed exclusively by phone calls. It consisted of a brief cognitive (Modified Telephone Interview for Cognitive Status - TICS-M) and anxiety/depression screenings, in addition to the SCD-scale (Figure 1). Between March and November 2022, 52 SCD patients were included, 73.1% (n = 38) women. Their median interquartile range (IQR) age was 70 (68-73) years old, with 16 (9.25-19) years of formal education and median score of 28.5 (IQR 26,30) on Mini Mental State Examination (MMSE) (Table 1). Percentage of agreement on the presence of cognitive complaints between informants and patients was 38.5%. The main SCD-plus criteria were the age at onset of SCD ≥ 60 years old (84.6%, n = 44) and concerns associated with SCD (78.8%, n = 41). The key findings of the neuropsychological assessment are reported in Table 2. Deficits were observed mainly in memory and executive functioning domains. Explorative analysis showed that Cognitive Reserve Scale scores correlated positively with MMSE (rho = 0.311; p = 0.02) and with formal education (rho = 0.541; p<0.001) and negatively with CDR-sum of boxes (rho = -0.307; p = 0.03). The prevalence of APOE ε4 carriers was 29.8% (n = 14) and a dementia family history was more frequent in APOE ε4 carriers - 12 (85.7%) - than non-carries, 12 (36.4%). The increase in the sample size, especially with individuals with low education, associated with AD biomarkers analysis and long-term follow-up may bring valuable information about the progression of SCD to cognitive decline in Brazil. We estimate that a total of 150 individuals will be included by the end of 2023.