Sharpening a Second Language: An Edge Against Alzheimer's Disease

Multilingualism may offer more benefits than simply proficiency with another language. For one, being able to speak more than one language leads to morphological change in the brain - an increased amount of grey matter. Secondly, and of vital importance to the discussion of Alzheimer’s, multilingualism can act as a buffer to the deteriorating effects of this disease.

In order to explore these two lines of research, Duncan et al. (2018) placed a focus on examining differences of tissue density and cortical thickness between monolingual and multilingual mild cognitive impairment (MCI) or Alzheimer’s disease (AD) patients. Additionally, they measured memory performance to find out whether or not grey matter in language and cognitive control (LCC) regions enhance disease-related (DR) cognitive performance, as means to confirm the presence of a cognitive reserve hypothesized to exist for multilingual patients. The authors also made effort to eliminate immigration as a confounding variable, by focusing on native-born Canadians exclusively.

Striking differences were found between the multilingual and monolingual patient groups. First, for the medial temporal DR areas, there was increased tissue density amongst multilingual MCI patients. Notably, when looking at AD patients, there was hardly a difference - either similar or lower densities were found amongst the multilingual patients. Second, for the LCC regions, thicker cortex were found in both multilingual MCI & AD patients. Lastly, cortical thickness was found to be linked with stronger memory functioning as measured in the memory tasks. All of the results highlight the benefits of multilingualism with respect to preservation of cognitive ability upon the advent of Alzheimer’s disease. These findings culminate in a understanding of how for those multilingual patients, increased tissue density and cortical thickness provide a buffer for the brain atrophy underlying Alzheimer’s, and ultimately the deteriorating cognitive capabilities for those with the disease. Additionally, both the lessened tissue densities found in multilingual AD patients and increased LCC region grey matter’s enhancement of cognitive performance provide support for the cognitive reserve hypothesis in that those with Alzheimer’s can still function reasonably well with less, but also benefit from more.

The authors provide valuable new data by utilizing new perspectives in examining differences between multilingual and monolingual groups to provide innovative reasoning towards the value of multilingualism towards Alzheimer's disease by way of beneficial brain plasticity.

---

Source:

• Duncan, H. D., Nikelski, J., Pilon, R., Steffener, J., Chertkow, H., & Phillips, N. A. (2018). Structural brain differences between monolingual and multilingual patients with mild cognitive impairment and Alzheimer disease: Evidence for cognitive reserve. Neuropsychologia, 109, 270-282. doi:10.1016/j.neuropsychologia.2017.12.036