Factors that predict cognitive decline in patients with subjective cognitive impairment

Current evidence supports the concept of a preclinical phase of Alzheimer's disease (AD) where pathological and imaging changes are present in asymptomatic individuals. Subjective cognitive impairment (SCI) may represent the earliest point on the continuum of AD. A better understanding of the baseline characteristics of this group of patients that later decline in cognition will enhance our knowledge of the very early disease processes, facilitate preventive strategies, early diagnosis, timely follow-up and treatment.

An observational exploratory study which followed up 62 consecutive patients with SCI presenting to a memory clinic and compared baseline characteristics of SCI patients who declined cognitively with those who did not. Cognitive decline was defined as a progression to a diagnosis of amnestic mild cognitive impairment (aMCI) or dementia at follow-up.

Patients were followed up for a mean of 44 months (range 12-112 months). At the time of follow up, 24% of patients had declined. Patients that declined were significantly older at onset of symptoms and first presentation to memory clinic, and took significantly more medications for physical illnesses. Patients that declined also performed significantly worse on Trail Making Test (TMT) B and Cambridge Cognitive Examination - Revised (CAMCOG-R) at baseline. Survival analysis identified key variables that predicted decline (later age of onset and later age at first assessment).

Patients who present with subjective memory complaints and are over the age of 61 years are at high risk of cognitive decline and warrant an in-depth assessment and follow-up.