Interindividual variability in vocabulary, sentence comprehension and working memory is studied in older people with mild cognitive impairment, very low cognitive impairment and normal state, according to the Mini Examen Cognoscitivo (MEC). In the study participated 71 seniors, aged between 62 to 90 years of age, with low instructional level (from one to five years of regular education). Variability measures were calculated in a test of lexical knowledge, another of working memory, and also in one of sentence comprehension.

The results obtained using a polynomial regression analysis of the absolute residual scores on the MEC, showed that: (a) variability increases in a linear fashion as the MEC score decreases in the case of nouns, and sentences with one proposition that do not follow the canonical order of constituents in Spanish; (b) Performance on the simpler sentences (one proposition and canonical order) and in the most complex ones (two propositions and non-canonical order) variability showed a change in its trend from MEC scores that indicate cognitive deterioration; (c) In relation to performance on the verbs, variability’s change of trend is not linked to cognitive deterioration. We discuss the results in terms of the utility of these measures as potential indicators of cognitive impairment.