Background Our objectives were (1) to test the association between the report of subjective cognitive decline (SCD) and prospective objective cognitive performance in high age individuals and (2) to study the course of longitudinal cognitive performance before and after the first report of SCD. Methods Cognitively normal elderly participants of the German Study on Ageing, Cognition, and Dementia study (N = 2330) with SCD (subjective decline in memory with and without associated concerns) and without SCD at baseline were assessed over 8 years with regard to immediate and delayed verbal recall, verbal fluency, working memory, and global cognition. Baseline performance and cognitive trajectories were compared between groups. In addition, cognitive trajectories before and after the initial report of SCD (incident SCD) were modelled in those without SCD at baseline. Results Baseline performance in the SCD group was lower and declined more steeply in immediate and delayed verbal recall than in the control group (no SCD at baseline). This effect was more pronounced in the SCD group with concerns. Incident SCD was preceded by decline in immediate and delayed memory and word fluency. Conclusions SCD predicts future memory decline. Incident SCD is related to previous cognitive decline. The latter finding supports the concept of SCD indicating first subtle decline in cognitive performance that characterizes preclinical Alzheimer's disease.

Our results indicate a link between the gray matter atrophy pattern of patients with AD and the presence of SMI. Furthermore, multivariate pattern recognition approaches seem to be a sensitive method for identifying subtle brain changes that correspond to future memory decline in SMI.

The feature binding task detects subtle cognitive impairments in participants with SCD, who are unimpaired in traditional neuropsychological testing. This corroborates the use of feature binding tests in preclinical AD studies and suggests that specific cognitive deficits can be found in SCD. Future studies incorporating AD biomarkers and longitudinal follow-up are needed to further establish the clinical utility of feature binding.

High prevalence of biomarker abnormality and clinical progression, together with the predictive value of CSF biomarkers, in memory clinic patients with SCD support the validity and usefulness of this condition as a "pre-MCI" at risk stage of AD.

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Our longitudinal observations suggest that dementia risk may be reduced by some but not all types of mental work demands.

In MCI, specific aspects of SCD severity and quality are related to CSF biomarkers indicative of AD. This extends findings in pre-MCI samples and calls for an improved operational assessment of SCD in MCI. This might be useful for sample enrichment strategies for increased likelihood of AD pathology.

Associative memory is substantially impaired in memory clinic patients with SCD and correlates specifically with memory complaints at this putative preclinical stage of AD. Further studies will need to examine the predictive validity of the FNART in SCD patients with regard to longitudinal (i.e., conversion to MCI/AD) and biomarker outcomes.