Affiliations: [a] Kyung Hee University, Research Group of Pain and Neuroscience, Seoul, Republic of Korea
| [b] Department of Communication Sciences and Disorders, Long Island University, Brooklyn, NY, USA
| [c]
Psychiatric Research Group, LVR-Klinik Bedburg-Hau, Bedburg-Hau, Germany
| [d] Department of Medicine, Neurology, University of Fribourg, Fribourg, Switzerland
| [e] Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
Correspondence:
[*]
Correspondence to: Maurits van den Noort, Research Group of Pain and Neuroscience, Kyung Hee University, #1 Hoegi-Dong, Dongdaemun-gu, Seoul 130-701, Republic of Korea. Tel.: + 49 2821 7114743; E-mail: info@mauritsvandennoort.com.
Abstract: In a recent article of the Journal of Alzheimer’s Disease, Hack et al. (2019) argue that linguistic ability rather than multilingualism is a significant predictor of dementia. In their longitudinal study, they investigated 325 religious sisters who were older than 75 years of age. Self-reports were used in order to determine multilingualism. They found that speaking two or three languages did not delay the onset of dementia. However, they did find that individuals speaking four or more languages were less likely to suffer from dementia than those speaking only one language and concluded that having linguistic ability was a more significant predictor of dementia than being multilingual. However, more research is needed in order to identify the characteristics of multilingualism most salient for the risk of dementia. In this commentary, we raise several important methodological and statistical issues that are likely to have affected the findings of Hack et al.’s study. As a result, although their study makes an important contribution to the research field, drawing a conclusion at this time that linguistic ability is more a predictor of dementia than multilingualism would be premature; moreover, their preliminary results cannot be generalized to the general population.
Keywords: Dementia, idea density, linguistic ability, longitudinal, multilingualism, risk
