Sex-, age-, and education-adjusted norms for Cambridge Neuropsychological Test Automated Battery in literate Sri Lankan adults

Objective: Neuropsychological test batteries validated for Sri Lankan population are extremely scarce. Cambridge Neuropsychological Test Automated Battery (CANTAB) is a language-independent test battery used in many countries, but the original UK norms may not be representative in the local setting due to sociocultural differences. Our aim was to generate age-, sex-, and education-adjusted norms for the CANTAB for Sri Lankan adults.

Method: Three-hundred and eleven healthy, community-living adults aged 20–64 years completed CANTAB subtests of visual attention (Reaction Time and Rapid Visual Information Processing), visual memory (Paired Associates Learning and Delayed Matching to Sample); and executive functions (Stockings of Cambridge, Stop Signal Task, and Spatial Working Memory). We conducted multiple linear regression analyses with sex, age and years of education fitted as predictors to model the CANTAB outcome variables.

Results: Younger age and longer education were associated with better performance in most CANTAB measures. Men outperformed women in few measures of psychomotor speed and visuospatial skills, but sex explained only a small proportion of test variance. We report regression equations to predict CANTAB norms based on sex, age and years of education; and the test variances accounted by these factors.

Conclusions: We propose sex-, age- and education-adjusted CANTAB norms for Sri Lankans aged 20–64 years and supplement the regression formulae with a calculator that produces predicted and standard scores of a given test subject. These norms would help in interpreting the results of clinical samples in future studies, taking into account the variability introduced by sex, age and education.