Longitudinal study on subjective cognitive complains from patients and informants: Differences between stable and worsening SCD and MCI participants and prediction of cognitive decline

Background Subjective cognitive complaints (SCCs) are a risk factor to dementia. Self‐ and informant‐reports may have different predictive validity along the cognitive decline continuum. We aimed to analyze longitudinal differences between self‐ and informant‐reports in stable(‐s) and worsening(‐w) SCD and MCI participants, and the predictive value of these reports on cognitive worsening at different stages of cognitive decline. Method A total of 216 participants with SCCs from the CompAS study were longitudinally assessed three times (intervals 18‐24 months). SCD (190) and MCI (26) participants were classified as stable or worsening at the last follow‐up. SCCs from participants and informants were evaluated through the QAM, and depressive symptoms through the GDS‐15. SCD participants were classified as Low (L‐SCD=119) and High (H‐SCD=71) complainers (below and above 5%ile in self QAM scores). Mixed‐ANOVAs tested differences between the stable and worsening groups (L‐SCD‐s; H‐SCD‐s; L‐SCD‐w; H‐SCD‐w; MCI‐s; MCI‐w) in the three QAM measurements for participants and informant. Logistic regressions were performed to analyze if QAM scoring of participants and informants at each assessment time predicts worsening. Results Significant main effect of Group [ F (1,5)=40.15, p < .001, ηp 2 =.489] showed QAM self‐reports (Figure 1A) were lower for L‐SCD‐s than for H‐SCD‐s, H‐SCD‐w, MCI‐s, MCI‐w; and higher for H‐SCD‐s than for L‐SCD‐s H‐SCD‐w, MCI‐s, MCI‐w. For QAM informant‐reports (Figure 1B) significant Group*Measurement interaction was found, [ F (10,294)=2.91, p =.002, ηp 2 =.090] indicating (Bonferroni tests) that QAM‐3 was higher than QAM‐1 and QAM‐2 for MCI‐w; and only QAM‐3 was higher for MCI‐w than for L‐SCD‐s, H‐SCD‐s, and MCI‐s. Covariate GDS‐15 score did not alter the results. Neither self‐ nor the informant‐reports predicted L‐SCD‐w. Self‐report‐QAM‐2 [ β =.300; SE =.088; p =.001; 95%CI =1.35(1.13–1.60)] and informant‐report‐QAM‐3 [ β = .314; SE =.119; p =.008; 95%CI =1.36(1.08–1.73)] significantly predicted H‐SCD‐w and MCI‐w [self‐report‐QAM‐2: β =.197; SE =.087; p =.023; 95%CI =1.21(1.02–1.44); informant‐report‐QAM‐3: β =.301; SE =.109; p =.006; 95%CI =1.35(1.09–1.67)]. Conclusions Cognitive complains from informants increased at the end of follow‐up for SCD and MCI participants who worsened compared to those who were stable, although significance was only achieved for the MCI‐w. Neither the self‐ nor the informant‐report showed predictive validity at baseline assessment. Self‐reports predicted progression earlier (QAM‐2) and informant‐reports later (QAM‐3).