Differential Impact of Education on Cognitive Performance in Neurological Patients with Progressive Cognitive Decline

BACKGROUND Education has a protective effect toward cognitive decline in advanced age and is an important factor contributing to cognitive reserve. OBJECTIVE To elucidate the interaction effect of education and global mental status on cognitive performance of older patients with progressive cognitive decline. METHODS This retrospective study included 1,392 patients. We performed moderation regressions to examine the interaction between education and global mental status (Mini-Mental State Examination (MMSE) score) on performance in episodic memory, executive functions (EF), language, and constructional praxis tests. Significant interaction effects were further explored through separate linear regressions by MMSE level (inferior: ≤24; intermediate: 25-27; superior: 28-30). RESULTS There was an interaction between MMSE and education for some but not all variables. At intermediate and superior MMSE levels, high-educated people had a clear advantage relative to low-educated people in verbal memory and EF tests. This advantage was not significant at an inferior MMSE level. In object naming, constructional praxis recall, and constructional praxis, high-educated people performed better than low-educated people, independently of MMSE level. CONCLUSION Education has a differential effect on cognitive performance in patients with cognitive decline. While high education is not helpful for episodic memory and EF at low cognitive levels, it is still beneficial for retrieving words or other semantic knowledge. These findings suggest an interaction between global mental status and education on different cognitive domains and have strong clinical implications. Diagnostic judgments should be based on the knowledge of such interaction. This study highlights the beneficial but selective effects of high education.