Lower semantic verbal fluency at baseline indicates future decline in subjective cognitive decline

Subjective cognitive decline (SCD) refers to a condition in which older adults are concerned that they are experiencing a decline in cognitive function. The risk of developing Alzheimer's disease (AD) is significantly higher in older adults with SCD, as a proportion of them will go on to develop the disease over the years. Despite overall normal function on cognitive tests, evidence suggests that some SCD individuals may have circumscribed deficits in specific cognitive domains or tests. This study aimed to investigate semantic function in SCD, specifically by comparing the performance of SCD progressors (SCDp) - who fulfilled MCI criteria at follow-up, and SCD non-progressors (SCDnp) - who either remained stable or reverted to normal cognition. The main hypothesis was that the SCDp group would show significantly lower semantic performance than the SCDnp group at baseline. We also expected the SCDp group to decline faster on semantic tests at the two-year follow-up assessment than SCDnp. Data from the CIMA-Q cohort were analyzed. The SCDp and SCDnp groups were formed by precisely matching 25 participants from each group based on age and education levels. Both groups were compared in terms of neuropsychological performance at baseline and follow-up. Independent samples t-tests or ANCOVAs were used to measure baseline performance in the semantic domain and other cognitive domains. To study longitudinal changes in cognitive performance at follow-up, two-factor ANOVAs were performed. At baseline, SCDp participants performed significantly worse than SCDnp participants on the Category (semantic) fluency test, although this difference was not maintained at follow-up. No difference was found in other cognitive domains at baseline. Longitudinal analyses showed that a significant decline in MoCA score was observed in the SCDp group only. The results of this study suggest that reduced verbal semantic fluency in older people with SCD may indicate a higher risk of future cognitive decline.