Dementia – Subjective Cognitive Decline
- Subjective cognitive decline indicates a subjective perception of cognitive decline by a patient, in the absence of objective findings on medical evaluation. When cognitive testing is performed, it is normal.
- While variations of the terminology of SCD have been around for decades, this 2014 paper advocated for the use of this terminology and established a framework around which to define and research this entity.
- In this 2014 framework, the exclusion criteria:
- Mild cognitive impairment, prodromal AD, or dementia
- Can be explained by a psychiatric or neurologic disease (apart from AD), medical disorder, medication, or substance use
- SCD is thought to represent an intermediate state between normal cognition and mild cognitive impairment.
- In Alzheimer’s disease, there are pathologic changes in the brain years before the onset of mild cognitive impairment and dementia. It is thought that some people with SCD may be in the “preclinical” stage of Alzheimer’s disease, in which there are already pathologic brain changes, but no objective findings on cognitive tests.
- SCD can resolve, stabilize, or progress.
- In people with SCD, there is a 4.5x risk of progression to MCI (mild cognitive impairment) or dementia over 7 years vs those without SCD.
- Given the lack of curative treatments for dementia, there is increasing focus on SCD and whether treatment at this stage may hold more promise for reversing cognitive decline.