Background:
Subjective cognitive decline (SCD), i.e. the self-perceived feeling of worsening cognitive
function, may be the first symptom of preclinical Alzheimers disease (AD) and other
dementias. However, not all individuals with SCD develop dementia. Stability of SCD,
i.e. repeated reports of SCD, could contribute to identify individuals at risk, as
stable SCD may more likely reflect the continuous neurodegenerative process of AD
and other dementias.
Methods:
Cox regression analyses were used to assess the association between stability of SCD
and progression to mild cognitive impairment (MCI) and dementia in data derived from
the population-based Leipzig Longitudinal Study of the Aged (LEILA75+).
Results:
Of 453 cognitively unimpaired individuals with a mean age of 80.5 years (SD= 4.2), 139 (30.7%) reported SCD at baseline. Over the study period (M= 4.8 years, SD= 2.2), 84 (18.5%) individuals had stable SCD, 195 (43.1%) unstable SCD and 174 (38.4%)
never reported SCD. Stable SCD was associated with increased risk of progression to
MCI and dementia (unadjusted HR = 1.8, 95%CI = 1.2 – 2.6; p < 0.01), whereas unstable SCD yielded a decreased progression risk (unadjusted HR
= 0.5, 95%CI = 0.4 – 0.7; p < 0.001) compared to no SCD. When adjusted for baseline cognitive functioning, progression
risk in individuals with stable SCD was significantly increased in comparison to individuals
with unstable SCD, but not compared to individuals without SCD.
Conclusions:
Our results, though preliminary, suggest that stable SCD, i.e. repeated reports of
SCD, may yield an increased risk of progression to MCI and dementia compared to unstable
SCD. Baseline cognitive scores, though within a normal range, seem to be a driver
of progression in stable SCD. Future research is warranted to investigate whether
stability could hold as a SCD research feature.
