COWAT Performance of Persons with Alzheimer Dementia, Vascular Dementia, and Parkinson Disease Dementia According to Stage of Cognitive Impairment.

BACKGROUND

The Controlled Oral Word Association Test (COWAT) evaluates frontal lobe and executive function. Therefore, it can be helpful in differentiating cognitive deficits. However, there are no studies comparing the COWAT performance according to the type and stage of cognitive impairment.

OBJECTIVE

To compare performance among persons with Alzheimer dementia (AD), vascular dementia (VaD), and Parkinson disease dementia (PDD) on the COWAT according to stage of cognitive impairment.

DESIGN

Retrospective chart review.

SETTINGS: University hospital rehabilitation psychology center.

PATIENTS: We reviewed the medical records of 246 persons diagnosed with mild cognitive impairment (MCI) or dementia using the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the Korean-Instrumental Activities of Daily Living (K-IADL). Patients were divided into a control group, Alzheimer groups (amnestic mild cognitive impairment [aMCI] + AD), Vascular groups (vascular mild cognitive impairment [VaMCI] + VaD), and Parkinson groups (Parkinson disease-mild cognitive impairment [PD-MCI] + PDD).

METHODS

Total scores (ie, total number of words produced in 60 seconds on the semantic and phonemic fluency tests of the COWAT) were analyzed. Secondary analysis included calculating percentage scores of words produced during each of the four, 15-second segments from the total number of words produced in each trial.

RESULTS

All MCI groups scored significantly lower than the control group on both semantic and phonemic fluency tests. Among the dementia groups, the VaD (mean ± SD, 5.6 ± 5.1) and PDD (5.5 ± 5.5) groups' scores were significantly lower and worse than that of the AD (11.0 ± 8.8) group on the phonemic test (P < .001). The difference in percentage scores was most marked between the PD-MCI (17.0 ± 2.2) and PDD (1.2 ± 3.1) groups, followed by the VaMCI (13.3 ± 1.9) and VaD (5.6 ± 1.8) groups on the latter phonemic test (P = .007).

CONCLUSIONS

The COWAT is a sensitive test of frontal-lobe and executive function impairment in persons with MCI. Decreased verbal output in the last 15 seconds of phonemic fluency test is significantly decreased and impaired in persons with VaMCI and PD-MCI compared to persons with aMCI as they progress to dementia.

LEVEL OF EVIDENCE: III.