Clinical Manifestations

Area of Science:

• Neuroscience
• Gerontology
• Cognitive Psychology

Background:

• Subjective cognitive decline (SCD) predicts neurocognitive disorders (NCD) but its nature is debated.
• Many individuals with SCD do not progress to NCD, leading to the concept of functional cognitive disorders.
• This study differentiates SCD trajectories in those who do and do not develop NCD.

Purpose of the Study:

• To examine distinct differences in subjective cognitive decline (SCD) trajectories.
• To compare SCD progression in individuals who develop neurocognitive disorders (NCD) versus those who remain cognitively normal.
• To inform early NCD risk identification and public health strategies.

Main Methods:

• A case-control study of 5,167 participants aged ≥50 years with a median follow-up of 8.1 years.
• Cases developed incident NCD; controls had normal cognition throughout ≥10 years of follow-up.
• Mixed-effect logistic regression modeled SCD trajectories using a backward timescale.

Main Results:

• Individuals who developed NCD showed new-onset SCD within 20 years, becoming prominent 13-14 years pre-diagnosis.
• Individuals who did not develop NCD reported SCD from a younger age with constant probability over time.
• These distinct SCD trajectories were consistent across Alzheimer's and non-Alzheimer's diseases and in those with psychiatric conditions.

Conclusions:

• Subjective cognitive decline (SCD) exhibits distinct trajectories differentiating progression to neurocognitive disorders (NCD).
• These trajectories can enhance early NCD risk assessment and guide public health messaging.
• Future SCD assessments may require a 20-year perspective to capture new-onset symptoms effectively.