Verbal fluency performance in alzheimer's disease

Alzheimer's Disease is a common type of dementia; characterized as progressive deterioration of semantic memory structure. The verbal fluency tests are tools frequently addressed with regard to evaluate cognitive functions such as language, attention and memory. However, the results are most usually measured by calculating the total word production, whereas the qualitative attributes of the test are being neglected. Lighting the way for a better understanding of functions of the different brain parts, the qualitative analysis of the test allows a more comprehensive interpretation of dementia types. This study examines two groups, one consisting of individuals suffering dementia and the other consisting of healthy people, via verbal fluency tests, and with the qualitative and quantitative evaluation of outcomes it compares the results derived from each group. In terms of quantitative analysis the total numbers of the words produced by each group have been evaluated and as for qualitative analysis clustering, switching, category intrusions and perseverations have been examined. The study group is consisting of the 20 participants who scored between 20-24 in the mini mental-state examination, and diagnosed with probable dementia by Osmangazi University Dementia polyclinic and Bezmialem University Dementia polyclinic. The control group is composed of 20 volunteers with no diagnosed neurological or psychiatric disorders. The groups are paired in accordance with age and education level factors, and the volunteers between the age of 69-82 and received educations of 0 to 5 years were included. In the study, both groups were examined with phonemic fluency and semantic fluency tests, and the areas in which the study group underperformed compared to the control group have been determined. In both phonemic fluency test total number of words produced, clustering (the word ratio in the selected sub-category) and switching (the frequency of switching between clusters) scores have been determined and the scores of two groups have been analogized. In addition, perseveration and category intrusion errors made by groups have been compared. The study concludes that, in comparison with the control group, Alzheimer group underperformed in each verbal fluency test, having lower scores of both tests in terms of total number of words produced. Regarding phonemic fluency test lower switching scores are observed, for semantic fluency the Alzheimer group's cluster size scores were significantly lower. In the aspect of the error patterns of control and Alzheimer groups, a significant difference is marked only for phonemic fluency test, in which Alzheimer group was observed having a higher number of category intrusions. Keywords: Verbal fluency, clustering, switching, Alzheimer's disease