Delayed Audiovisual Integration of Patients with Mild Cognitive Impairment and Alzheimer's Disease Compared with Normal Aged Controls

Article type: Research Article

Authors: Wu, Jinglong^{a; *} | Yang, Jiajia^a | Yu, Yinghua^a | Li, Qi^b | Nakamura, Naoya^a | Shen, Yong^{c; e} | Ohta, Yasuyuki^d | Yu, Shengyuan^f | Abe, Koji^d

Affiliations: [a] Biomedical Engineering Laboratory, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan | [b] Changchun University of Science and Technology, Changchun, Jilin, China | [c] Center for Advanced Therapeutic Strategies for Brain Disorders, The Roskamp Institute, Sarasota, FL, USA | [d] Graduate School of Medicine, Dentistry and Pharmacological Sciences, Okayama University, Okayama, Japan | [e] Institute of Neuroscience, Beijing Institute of Technology, Beijing, China | [f] Department of Neurology, Chinese PLA General Hospital, Beijing, China

Correspondence: [*] Correspondence to: Jinglong Wu, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan. Tel.: +81 86 251 8052; Fax: +81 86 251 8266; E-mail: wu@mech.okayama-u.ac.jp and Shengyuan Yu, Department of Neurology, Chinese PLA General Hospital, Fuxing Road 28, Beijing 100853, China. Tel.: +86 10 55499118; Fax: +86 10 88626299; E-mail: yusy1963@126.com.

Abstract: The human brain can anatomically combine task-relevant information from different sensory pathways to form a unified perception; this process is called multisensory integration. The aim of the present study was to test whether the multisensory integration abilities of patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) differed from those of normal aged controls (NC). A total of 64 subjects were divided into three groups: NC individuals (n = 24), MCI patients (n = 19), and probable AD patients (n = 21). All of the subjects were asked to perform three separate audiovisual integration tasks and were instructed to press the response key associated with the auditory, visual, or audiovisual stimuli in the three tasks. The accuracy and response time (RT) of each task were measured, and the RTs were analyzed using cumulative distribution functions to observe the audiovisual integration. Our results suggest that the mean RT of patients with AD was significantly longer than those of patients with MCI and NC individuals. Interestingly, we found that patients with both MCI and AD exhibited adequate audiovisual integration, and a greater peak (time bin with the highest percentage of benefit) and broader temporal window (time duration of benefit) of multisensory enhancement were observed. However, the onset time and peak benefit of audiovisual integration in MCI and AD patients occurred significantly later than did those of the NC. This finding indicates that the cognitive functional deficits of patients with MCI and AD contribute to the differences in performance enhancements of audiovisual integration compared with NC.

Keywords: Alzheimer's disease, audiovisual integration, cognitive functional deficits, mild cognitive impairment, performance enhancement

DOI: 10.3233/JAD-2012-111070

Journal: Journal of Alzheimer's Disease, vol. 32, no. 2, pp. 317-328, 2012