The BIOCARD Index: A Summary Measure to Predict Onset of Mild Cognitive Impairment

Abstract

Background: Changes in neuropsychological testing, neuroimaging, and cerebrospinal fluid may precede mild cognitive impairment (MCI). However, these markers are not routinely performed in outpatient clinical visits.

Objective: To evaluate whether a simple clinical index, consisting of questions given to patients and their informants, could predict the onset of symptoms of MCI among cognitively normal individuals.

Materials and methods: Two hundred twenty-two participants in the BIOCARD study received a detailed history, physical examination, and neuropsychological testing annually. An index was calculated by including questions about memory problems, depression, age, education, history of cerebrovascular disease risk factors, and brain injury, family history of dementia, and the Mini-Mental State examination score. Cox regression analyses were used to determine if this index score was related to diagnosis of MCI.

Results: The BIOCARD Index score mean for individuals who progressed to MCI was 20.3 (SD=2.9), whereas the score for individuals who remained normal was 24.8 (SD=2.3) (P<0.001) [hazard ratio, SE for subsequent diagnosis of MCI=0.75 (0.67 to 0.84); P<0.001].

Conclusions: Lower BIOCARD Index score predicted symptoms of MCI several years before the MCI diagnosis. The BIOCARD Index can be easily used in clinics to identify cognitively normal older individuals who are at risk for deterioration.

Figure 1

BIOCARD Index

FIGURE 2

Survival curve for the Cox regression model for individuals with a BIOCARD Index score above the median compared to individuals with a BIOCARD Index score below the median