Effects of transcranial direct current stimulation on the picture naming and phonemic fluency of aphasics / 中华物理医学与康复杂志

Objective:To observe any effect of transcranial direct current stimulation (tDCS) on the speed and accuracy of picture naming and on the phonological fluency of aphasic stroke survivors.Methods:Twenty-four stroke survivors with aphasia were randomly divided into an observation group and a control group, each of 12. In addition to language training and picture naming training, the observation group received 20 minutes of tDCS over the left dorsolateral prefrontal cortex (DLPFC) daily, 5 days a week for 2 weeks. The control group was given sham stimulation. Before and after the 2 weeks of treatment, both groups were tested for picture naming and phonological fluency.Results:Significant improvement in the number of accurately pronounced high-frequency words and in reaction time was observed in both groups, but the observation group′s average reaction time for high-frequency words was significantly shorter than the control group′s average. The observation group′s average reaction time for low-frequency words had also improved significantly. After the 2 weeks of treatment, the phonological fluency of the observation group was significantly better than before the treatment and better than that of the control group.Conclusions:tDCS applied over the left DLPFC of stroke survivors with aphasia can promote lexical retrieval and strengthen their executive and control functioning.

The Difference of Verbal Fluency Task Performance between Alzheimer's Disease and Subcortical Vascular Dementia: CREDOS (Clinical Research Center for Dementia of South Korea) Study

BACKGROUND: The verbal fluency test consists of two separate tests of semantic fluency and phonemic fluency. The performance patterns of these tests differ with the type of dementia. We studied the patterns of verbal fluency between Alzheimer's disease (AD) and subcortical vascular dementia (SVaD), and assessed the clinical utility of these tests. METHODS: The 1,475 selected participants comprised 73 normal control subjects, 673 patients with amnestic mild cognitive impairment (aMCI), 535 AD patients, 42 patients with subcortical vascular mild cognitive impairment (svMCI), and 152 SVaD patients. We analyzed the z-score for the total number of animal items as a semantic fluency index and the z-score of the phonemic total score as a phonemic fluency index. RESULTS: The performance of semantic fluency was lower than that of phonemic fluency in all groups. The SVaD group showed the worst scores and abnormal performances on both tests, while the AD group presented abnormal performance only for semantic fluency. Dividing the patients with dementia according to severity revealed a different pattern between AD and SVaD for the clinical dementia rating (CDR) stage of 0.5. The performance of the AD group declined gradually with CDR. However, the SVaD group performed very poorly in both tests even for very mild dementia (CDR stage of 0.5). The aMCI and svMCI groups exhibited similar performance patterns. CONCLUSIONS: The pattern of semantic and phonemic fluency was not clinically useful at the MCI stage, but it could be helpful in differentiating AD and SVaD in the early stage of dementia.

Usefulness of Verbal Fluency Performance as Follow-up Screening Tool in Patients With Mild to Moderate Alzheimer's Disease

BACKGROUND: Impaired verbal fluency in Alzheimer's disease (AD) has been well documented. Furthermore, crosssectional studies suggest that semantic fluency is disproportionately impaired relative to phonemic fluency in AD. The aim of this study was to determine the ability of fluency measures as follow-up screening tool for mild to moderate AD. METHODS: Participants were recruited from AD patients in mild to moderate stages. We annually evaluated semantic (animal, supermarket) and phonemic (giyeok, siot, ieung) fluency and tested other extensive neuropsychological measures for two years. RESULTS: A total of 33 AD patients were included at baseline and 1-year follow-up, who were aged 70.18+/-5.97 years at baseline. Eleven patients completed a 2-year follow-up. Phonemic fluency total score was not significantly changed during the study period. However, semantic fluency total score tended to decline annually, and significantly declined at 2-year follow-up compared to baseline. In addition, difference score (semantic fluency minus phonemic fluency) was significantly decreased at every follow-up compared to previous year. In Pearson correlation analyses between changes of verbal fluency and other neuropsychological measures, changes of semantic fluency appeared to be significantly correlated with neuropsychological measures much more than changes of phonemic fluency. CONCLUSIONS: Significant longitudinal declines in semantic fluency compared to phonemic fluency seem to be consistent with previous cross-sectional studies. These patterns of changes in verbal fluency were observed even at an interval of one year follow-up in our study. The verbal fluency might be useful follow-up screening test for mild to moderate AD in the memory clinic setting.