Objective: To determine whether the phonemic verbal fluency test is a purely cognitive measure or involves cognitive-motor interaction, if related to TMT.

Background: Two of the most used tests in clinical evaluation and scientific studies with PD patients are the Trail Making Test (TMT) and the VF. However, these tests are frequently interpreted as only providing executive function measures. Few studies consider them as cognitive-motor measures. Therefore, the motor component, which may be impaired, is overlooked. For TMT some extrapolations have been carried out, because part A involves mainly motor aspects and part B adds cognitive overload. The delta (part B – part A) isolates the cognitive performance. In the interpretation of VF, motor aspects are not considered. Therefore, a motor dysfunction (due to bradykinesia of phonoarticulatory muscles) can be interpreted as cognitive impairment.

Methods: Forty patients diagnosed with PD (Hoehn & Yahr 2-3) from the Movement Disorders clinic at the Hospital das Clinicas and twenty-seven healthy elderly controls participated. They had normal performance on Mini Mental State Examination (score above 24). Groups were similar in age and education. Evaluation consisted of TMT and phonemic VF. As the groups showed non-normal distribution, Spearman correlation tests were used to test relations between the variables for both groups separately. Significance level was set at alfa<0.05.

Results: Table 1 shows the correlations between VF and TMT. The scatterplots in figures 1 and 2 show the performance on part B and VF of both groups

Spearman correlation tests results for both groups

Phonemic fluency test	TMT A	TMT B	TMT delta
PD patients	-0,631	-0,733	-0,481
Healthy elderlies	-0,185	-0,249	-0,249

“. Healthy elderlies showed less variability in TMT performance. As manual dexterity and executive function are not affected in this group, no correlation was found. Considering the PD patients, the ones with higher cognitive reserve (as evidenced by faster performance on part B of TMT) also show less severe clinical manifestation of PD (assessed by part A of TMT). It is noted in the table, that VF and part B of TMT have strong correlation. The correlation between part A of TMT (motor performance) and phonemic VF was stronger correlation than the correlation between the delta (cognitive component) and VF.

Conclusions: Verbal fluency is a cognitive-motor test and, in PD patients, the interpretation of results as only cognitive assessment should be done with caution.

« Back to 2016 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/executive-function-and-verbal-fluency-in-patients-with-parkinsons-disease/