The state of cognitive functions and diffusion processes in the white matter of the cerebral hemispheres in healthy middle-aged and elderly people

Abstract

Background. The growing number of patients with dementia in aging population of developed countries significantly increases the relevance of differential diagnosis of cognitive impairment and age-associated cognitive disorders. The purpose of the study was to determine the criteria for physiological changes in cognitive status and diffusion processes in brain’s white matter in healthy middle-aged and elderly people. Material and ­methods. Thirty-nine healthy middle-aged (45–59 years, n = 19) and elderly patients (60–75 years, n = 20) were examined. Neuropsychological testing was performed using the following scales: Montreal Cognitive Assessment, Mini-Mental State Examination, Frontal Assessment Battery, Semantic Verbal Fluency (SVF) and Phonemic Verbal Fluency (PVF). Molecular diffusion in brain’s white matter was investigated by diffusion tensor imaging (Ingenia 3.0T, Philips). Results. Moderate positive correlations were found between age and the Frontal Assessment Battery score (rs = –0.443), memory (rs = –0.444) and executive function (rs = –0.542). Cognitive functions in middle-aged and elderly patients didn’t differ in cognitive domains of naming (II), memory (III), language (VIII), delayed reproduction (X), orientation (XI), semantic and phonemic verbal fluency. At the same time, differences in attention (IV, VI, AIS: p = 0.038; 0.043; < 0.001), language (VII, LIS: p < 0.001), abstraction (IX: p = 0.008) and visuospatial function (VIS: p = 0.002) were significant. Physiolo-gical age-related changes of molecular diffusion in the white matter of the cerebral hemispheres are characterized by a decrease of 21.0–37.0 % (p = 0.02 — < 0.001) in anisotropic and an increase of 16.3–29.5 % (p < 0.001) in free diffusion of water molecules in the conductive tracts and beyond them.