Bilingualism Delays Onset of Alzheimer's Disease

Speaking 2 languages can stall the onset of Alzheimer's disease by 4 years, according to self published research from investigators at Ghent University in Brussels, Belgium.

Between March 2013 and May 2014, the researchers assessed Alzheimer's disease (AD) patients referred to them by neurologists at Ghent University Hospital (82 patients) and Brussels University Hospital (51 patients). General patient data such as age, clinical manifestation diagnosis was based on, initial symptoms, short term memory or other cognitive problems were collected at the hospital. Language history and social background information was obtained from the patients and their caregivers by the researchers through interviews. The patients were asked to evaluate their proficiency using “perfect/native language,” “very good,” “good,” “moderate,” “poor,” and “non existing” labels for various languages. Participants were also asked how often they used those languages, such as early in school years, at work, or now. Scores ranged from 0-5 for proficiency and combined with scores from 5-0 for the age of speaking. A patient was considered bilingual if they rated themselves as “good” or higher in all skills and spoke the language at least weekly before now.

A total of 113 patients had some level of proficiency in a second language, while 9 patients reported a relatively good knowledge of a third or fourth language. There were 69 monolingual patients included, which consisted of 68 Dutch and 1 French speaking patients. There were 65 bilingual patients included in the analysis, which made up 45 Dutch, 18 French, 1 Spanish, and 1 English speaking patients. The English and Spanish speaking patients indicated they were raised bilingually and listed Dutch as their second language. Most patients’ second languages were Dutch or French, though 2 patients reported German and English.

The single language speakers indicated their basic knowledge in another language was learned at school through limited obligatory courses around age 10 years, but did not continue the use throughout their life. In the bilingual group, the ages of acquisition (AoA) ranged from birth to age 25 years, with the breakdown as follows:

- age 0-3 years: 18 patients

- age 3-6 years: 6 patients

- age 6-12 years: 21 patients

- age 12-18 years: 16 patients

- age 18-25 years: 4 patients

Bilingualism delayed the manifestation of AD by 4.6 years, the researchers concluded. The expected age for monolinguists was 71.5 years and 76.1 years for bilinguals. Diagnosis age was delayed in bilinguals by 4.8 years - the expected age for diagnosis in monolinguists was 72.5 years, and 77.3 years for bilinguals.

The researchers also analyzed the factors of occupation (unemployed, unskilled workers/ skilled workers/ professionals, managers), gender, and education, but found no relevant associations.

Their results were aligned with many studies in the current literature, which suggest bilingualism delays the symptoms of dementia. The researchers believe their findings are important not only for the cognitive well being of patients but also shaping healthcare policy.