Although knowing two languages may be able to delay the onset of Alzheimer’s, researchers from Canada’s York University have found that it may also accelerate brain deterioration into severe forms of the disease after it has taken hold.
For their study, the researchers recruited 158 patients diagnosed with mild cognitive impairment and monitored them over five years. Each participant was matched on age, education and cognitive levels and accordingly categorized as either bilingual with a high cognitive reserve or monolingual with a low cognitive reserve.
Over the five-year period, each person’s cognitive abilities were measured at six-month intervals to assess their progression from mild cognitive impairment to Alzheimer’s disease. In the end, while the researchers found that those in the monolingual group took an average of 2.6 years to make this progression, those in the bilingual group took only 1.8 years.
So what accounted for this difference? In their study, the researchers concluded it was likely that the bilingual people had larger neuropathology at the time of their diagnosis of mild cognitive impairment than their monolingual counterparts. This came despite the cognitive levels between the two groups being similar at the beginning of the research.
Lead author of the study, Ellen Bialystok said, “Imagine sandbags holding back the floodgates of a river...At some point the river is going to win. “The cognitive reserve is holding back the flood and at the point that they were when they were diagnosed with mild cognitive impairment they already had substantial pathology but there was no evidence of it because they were able to function because of the cognitive reserve. When they can no longer do this, the floodgates get completely washed out, so they crash faster.”
Although being bilingual may seem like a double-edged sword, it does nevertheless mean that those who are bilingual are better able to stave off Alzheimer’s for longer than those who are just monolingual. Bialystok added, “Given that there is no effective treatment for Alzheimer’s or dementia, the very best you can hope for is keeping these people functioning so that they live independently so that they don’t lose connection with family and friends...That’s huge.”