Improving Prediction of Dementia in Primary Care

Abstract

Purpose: The Mini-Mental State Examination (MMSE) is one of the most widely used instruments to screen for cognitive deficits; however, this instrument alone is not sensitive enough to detect early symptoms of dementia. We aimed to investigate whether additionally using the Visual Association Test (VAT) improves the predictive value of the MMSE score for development of dementia.

Methods: Analyses were based on data from 2,690 primary care patients aged 70 to 78 years who participated in the Prevention of Dementia by Intensive Vascular Care (preDIVA) trial. We assessed change in the 30-point MMSE score over 2 years and the VAT score at 2 years-dichotomized as perfect (6 points) or imperfect (≤5 points)-and evaluated the predictive values of these tests for a diagnosis of dementia in the subsequent 4 to 6 years. Data were analyzed with logistic regression analysis.

Results: Patients having a decline of 2 points or more in total MMSE score over 2 years had an odds ratio of 3.55 (95% CI, 2.51-5.00) for developing dementia. Patients having the same decline in MMSE score plus an imperfect VAT score had an odds ratio of 9.55 (95% CI, 5.89-15.41) for developing dementia. A 1-point decline in MMSE score increased odds of dementia only when the VAT score was imperfect. Dementia risk for patients with a 2- or 3-point decrease in MMSE score and a perfect VAT score did not differ significantly from the average risk of the cohort as a whole.

Conclusions: Administering the VAT in patients with a small decline on the MMSE over a 2-year period has substantial incremental value for identifying those at elevated risk for developing dementia. This simple test may help distinguish older adults who need further cognitive examination from those in whom a watchful waiting policy is justified.

Keywords: cognition; dementia; family practice; neuropsychological tests; practice-based research; primary care.

Figure 1

Example of cue and target cards used in the Visual Association Test. Note: Cue card on the left and target card on the right. First, patients are shown the cue cards one at a time and asked to name the object(s) (eg, “an ape”). Next, patients are shown the target cards and again asked to name the object(s) (eg, “an ape holding an umbrella”). Finally, patients are shown the cue cards again one at a time and asked to name the missing object (eg, “an umbrella”). Patients are not told to remember any objects, so the test requires incidental learning.

Figure 2

Incident dementia according to change in MMSE score alone (A) and according to change in MMSE score combined with VAT score (B). MMSE = Mini-Mental State Examination; VAT = Visual Association Test. Note: Left of center, patients who improved in total MMSE change score over 2 years; right of center, patients who had decline in MMSE change score over 2 years. ^a VAT score dichotomized as perfect (6 points) or imperfect (≤5 points).

Figure 2

Incident dementia according to change in MMSE score alone (A) and according to change in MMSE score combined with VAT score (B). MMSE = Mini-Mental State Examination; VAT = Visual Association Test. Note: Left of center, patients who improved in total MMSE change score over 2 years; right of center, patients who had decline in MMSE change score over 2 years. ^a VAT score dichotomized as perfect (6 points) or imperfect (≤5 points).