To determine the validity and reliability of a rapidly administered neurocognitive screening battery consisting of 4 brief tests (Enhanced Cued Recall, Temporal Orientation, Verbal Fluency, and Clock Drawing) to distinguish between patients with probable Alzheimer's disease (AD) and healthy control subjects.
Sixty successive referrals to the Memory Disorders Clinic at Southwestern Vermont Medical Center, Bennington, who were diagnosed as having probable AD and 60 community-dwelling volunteers of comparable age, sex distribution, and education.
Interrater and test-retest reliability, intergroup comparisons between patients with AD and control subjects on the 4 individual tests, and determination of probability of dementia for patients with AD and control subjects using the entire battery of tests.
Main Outcome Measure
Comparison of the probability of dementia on the 7 Minute Screen with the criterion standard of clinical diagnosis established by examination and laboratory studies.
Secondary Outcome Measures
Test-retest and interrater reliability (correlation coefficients), time for administration.
Mean time of administration was 7 minutes 42 seconds. Mean scores for patients with AD and control subjects on all 4 individual tests were significantly different (for each, P<.001). When the 4 tests were combined in a logistic regression, the battery had a sensitivity of 100% and a specificity of 100%. A series of 1000 repeated random samples of 30 patients with AD and 30 control subjects taken from the overall sample of 60 patients with AD and 60 control subjects had a mean sensitivity of 92% and a mean specificity of 96%. The battery was equally sensitive to patients with mild AD as demonstrated by correctly classifying all 13 patients with AD using Mini-Mental State Examination scores of 24 or higher. Neither age nor education was a statistically significant factor when added as a covariate. Test-retest reliabilities for individual tests ranged from 0.83 to 0.93. Test-retest reliability for the entire battery was 0.91. Interrater reliability for the entire battery was 0.92.
The 7 Minute Screen appears highly sensitive to AD and may be useful in helping to make initial distinctions between patients experiencing cognitive changes related to the normal aging process and those experiencing cognitive deficits related to dementing disorders such as AD. It has reasonable interrater and test-retest reliability, can be administered in a brief period, and requires no clinical judgment and minimal training.