Objective:To explore commonalities and differences in the sociodemographic, health, and neuropsychological characteristics of participants with SCD recruited in two culturally differentiated cohort studies, namely CIMA-Q (Canada; Bellevile et al., 2019) and CompAS (Spain; Juncos et al., 2012).
Methods:Older adults with subjective cognitive complaints of the CompAS (N=251; 68.92% women; Control: 30.3%; SCD: 25.9%; MCI: 28.7%) and the CIMA-Q (N=179; 71.5% women; Control:16.1%; SCD: 36.8%; MCI:28.6%) were recruited, respectively, from primary care centers and memory clinics, excluding patients with dementia and other neurological or psychiatric disturbances. Cognitive complaints were assessed considering coincident items of the QAM and MFE questionnaires. Cut-off points for the 5%ile were calculated independently in both samples and according to this, participants were classified as SCD or controls (CompAS: N= 141; CIMA-Q: N=161) considering complaints relevance at baseline (Pereiro et al., 2021). Participants underwent neuropsychological assessment. Participants diagnosed as Mild Cognitive Impairment (MCI) were excluded from the analysis. Between cohort-studies and inter-group (control, SCD) differences were tested in the sociodemographic, health and neuropsychological measures considered. The Holm-Bonferroni correction was applied to reduce the probability of type I error (p<.003).
Results:Identical cut-off points for 5%ile were obtained in both samples though SCD prevalence was slightly higher in CIMA-Q. For both samples, equivalence between Control and SCD participants in sociodemographic, health, functionality, and neuropsychological measures was observed. Only complaints and depressive symptomatology was significantly higher in SCD participants than in controls in both CompAS and CIMA-Q studies.
Participants of the CIMA-Q, Controls and SCD, showed significantly higher age, cognitive reserve proxies, comorbidity, and better attentional performance than the CompAS participants (see Table 1). CompAS participants, Controls and SCD, showed more neuropsychiatric symptomatology than CIMA-Q participants (see Table 1).
Conclusions:Control and SCD participants showed equivalence on sociodemographic, health, functional, and neuropsychological measures in both studies. However, significant between-sample differences in the two groups, particularly in SCD participants, were observed in sociodemographic, health, cognitive reserve, behavioral and attentional measures. Identification of these factors are critical to analyze the transcultural validity of cognitive complaints in predicting progression to AD.
Table 1Between group (control, SCD) and Between study (CIMA-Q, CompAS) differences in sociodemographic, health, and cognitive measures
| CIMA-Q | CompAS | Between-studies differences |
| Between-group differences | Between-group differences | Control | SCD |
Sociodemographics |
Age | NS | NS | CIMA-Q>CompAS; F(1,124)=22.78; p<.001 | CIMA-Q>CompAS; F(1,172)=36.97; p<.001 |
Gender | NS | NS | NS | NS |
Schooling (years) | NS | NS | NS | CIMA-Q>CompAS; F(1,172)=20.74; p<.001 |
Prof. qualification | NS | NS | CIMA-Q>CompAS; χ24=18.18; p=001 | CIMA-Q>CompAS; χ24=33.95; p<001 |
Cognitive reserve (quartiles) | NS | NS | CIMA-Q>CompAS; χ23=13.57; p=004 | CIMA-Q>CompAS;χ23==42.56; p<001 |
Memory familiar antecedents | NS | NS | NS | CIMA-Q>CompAS; χ21==15.03; p<001 |
Neuropsychology |
Subjective complaints* | SCD>Control; F(1,119)=147.17, p<.001) | SCD>Control; F(1,177)=192.87, p<.001 | NS | NS |
Charlson Index* | SCD>Control; F(1,115)=5.29, p=.023 | NS | CIMA-Q>CompAS; F(1,123)=394.96; p<.001 | CIMA-Q>CompAS; F(1,168)=335.98; p<.001 |
General cognition | NS (MoCA) | NS (CAMCOG-R) | -- | -- |
GDS-15* | SCD>Control; F(1,119)=8.60, p=.004 | SCD>Control; F(1,176)=11.97, p<.001 | NS | NS |
TMT-A (secs.)* | NS | NS | NS | NS |
TMT-B (secs.)* | NS | NS | CompAS>CIMA-Q; F(1,118)=12.56; p<.001 | CompAS>CIMA-Q; F(1,163)=21.74; p<.001 |
Verbal fluency | NS | NS | NS | NS |
Semantic fluency | NS | NS | NS | NS |
Boston test | NS | NS | NS | NS |
NPI-Q | NS | NS | CompAS>CIMA-Q; F(1,119)=16.68; p<.001 | CompAS> CIMA-Q; F(1,162)=24.46; p<.001 |
Immediate recall (RAVL test) | NS | NS | NS | NS |
Short delay (RAVL test) | NS | NS | NS | NS |
Long delay(RAVL test) | NS | NS | NS | NS |
Intrusions (RAVL test) | NS | NS | NS | NS |
IAVD* | NS | NS | NS | NS |
Note: *On these measures, higher scores denote worse cognition or health condition. TMT: Trail Making Test (A and B forms); NPI-Q: Neuropsychiatric Inventory-Questionnaire; RAVL: Rey Auditory Verbal Learning; IAVD: Instrumental Activity of Daily Living.