The influence of deep brain stimulation on verbal learning in Parkinson’s disease

• Published in: Higher Brain Function Research Vol. 33; no. 2; pp. 245 - 252
• Main Authors: Tsuboi, Rika, Shirokawa, Tetsuya, Horiba, Mitsuya, Yamashita, Yutaka Yutaka, Wada, Ikuo, Umemura, Atsushi, Mimura, Masaru
• Format: Journal Article
• Language: English; Japanese
• Published: Japan Society for Higher Brain Function 30.06.2013
• Subjects: attention; deep brain stimulation; Parkinson's disease; subthalamic nucleus; verbal learning
• ISSN: 1348-4818; 1880-6554
• DOI: 10.2496/hbfr.33.245

Subthalamic nucleus deep brain stimulation(STN-DBS)is known to improve motor functions of individuals with Parkinson's disease but some adverse effects may also have been reported including cognitive and/or affective dysfunction. In the present study, the effect of STN-DBS on verbal learning was investigated in Parkinson's disease. The participants were 45 patients with Parkinson's disease who received bilateral STN-DBS. The mean age of the participants was 62.8 ± 8.9 years. The motor function of the patients significantly improved and the dosage of dopaminergic agents successfully decreased postoperatively. Scores on the Rey Auditory Verbal Learning Test(RAVLT)were measured and compared pre-and postoperatively as well as those on the Digit Span, MMSE, and Modified Stroop Test. Verbal learning activities as indexed by delayed recall scores and recognition scores of RAVLT were equivalent pre-and postoperatively. However, close observation of the serial learning curve of RAVLT demonstrated dullness of improvement in the 4th and 5th trials following STN-DBS, which suggests impaired learning efficacy postoperatively. In addition, Digit Span, overall MMSE scores, Modified Stroop Test particularly in the condition with response inhibion, also showed deterioration following STN-DBS. The results suggest that STN-DBS did not impair long-term verbal learning capacity per se, but did impair learning efficacy in mnemonic activities as well as simple and complex attention caused by STN-DBS.