Development of a Universal, Multilingual Word Set for Assessing Verbal Memory and Enhancing Cognitive Assessment

Introduction and problem statement

Verbal memory has been researched extensively as a means of differentiating and classifying disease populations from healthy individuals ^1,2. Many of the most common word recall tasks used in clinical practice in the United States are derived from classic neurologic assessments. For example, the Mini-Cog™ is a brief pencil-and-paper screening tool commonly used to assess cognition in populations with known or suspected cognitive impairment ^3,4. It pairs immediate and delayed word recall with a clock drawing task to assess memory, attention, and executive functioning. Traditionally, the Mini-Cog provides six, 3-word sets so that when the test is administered at different time points, different word sets can be used to avoid learning and carry-over effects. However, while appropriate for American English speakers, some of the words used in the recall task have less relevance in other languages or are overly complex, and are subsequently more difficult to remember. This has spurred  the need for a universal word set to drive consistency and enhance the value of word recall in cognitive assessments.

Proposed solution and findings

Linus Health has constructed a new, cross-linguistically applicable set of words for use in word recall sets based on our recently completed research. In addition to being able to use the same sets of words across languages, the goal was to create a set of words that are commonly occurring (as determined by word frequency) and of similar speech sound (phoneme) complexity. To perform more sophisticated speech and voice production analyses, vowel diversity was a secondary focus of the new word set; recently, researchers have examined specific motor speech features extracted from acoustic signals of vowels in words to differentiate disease populations from healthy individuals. These analyses require a diverse set of vowel productions, including both central (produced with the tongue at rest in the center of the mouth) and non-central (requiring some movement of the tongue to produce). Thus, more can be inferred about speech motor ability, cognition, and vocal health and quality. Table 1 describes the important features of the original and new word sets in terms of the average normalized frequency of occurrence, phonemic complexity index, and counts of central and non-central vowels. Words in the Linus Health Universal Word Set have been adapted to six languages: American English, Spanish, Portuguese, Hindi, Persian (Farsi), and German, with several others planned.

Table 1. The six 3-word sets traditionally used in the Mini-Cog and the proposed new Universal Word Set.

Conclusion

Linus Health has adopted a multilingually applicable word recall set using more frequently-occurring words, with decreased phonemic complexity, and increased vowel diversity compared to traditional word sets used in immediate and delayed verbal recall tasks within cognitive assessments. This universal word set will be translated and used across the most spoken languages worldwide to enhance the global usability of cognitive assessments with verbal recall components. Decreased phonemic complexity will increase the generalizability of words and decrease difficulty in pronunciation/reading. Finally, the diversity of speech sounds present in the universal word set will allow for more sophisticated analysis, correlations, and subsequent brain health insights and recommendations.

References

1. Silva D, Guerreiro M, Maroco J, et al. Comparison of Four Verbal Memory Tests for the Diagnosis and Predictive Value of Mild Cognitive Impairment. Dement Geriatr Cogn Disord Extra. 2012;2(1):120-131. doi:10.1159/000336224
2. Di Lorenzo F, Motta C, Bonnì S, et al. LTP-like cortical plasticity is associated with verbal memory impairment in Alzheimer’s disease patients. Brain Stimulat. 2019;12(1):148-151. doi:10.1016/j.brs.2018.10.009
3. Borson S, Scanlan J, Brush M, Vitaliano P, Dokmak A. The mini-cog: a cognitive “vital signs” measure for dementia screening in multi-lingual elderly. Int J Geriatr Psychiatry. 2000;15(11):1021-1027. doi:10.1002/1099-1166(200011)15:11<1021::aid-gps234>3.0.co;2-6
4. Borson S, Scanlan JM, Chen P, Ganguli M. The Mini-Cog as a Screen for Dementia: Validation in a Population-Based Sample: MINI-COG IN MOVIES. J Am Geriatr Soc. 2003;51(10):1451-1454. doi:10.1046/j.1532-5415.2003.51465.x
5. Davies M. Corpus of News on the Web (NOW): 10 billion words from 20 countries, updated every day. Published online 2016.