Pathophysiology of cognitive dysfunction and the role of combined brain/heart magnetic resonance imaging (Review).

Normal cognitive function depends on a continuous and optimally regulated blood supply, and any pathology that further reduces cerebral blood perfusion in addition to that caused by aging could damage or destroy vulnerable neurons of the brain. Furthermore, glucose serves a crucial role as the primary fuel source for the mammalian brain and any disturbance in its circulating concentrations could directly affect brain function. The term cognitive dysfunction (CD), known also as 'brain fog', refers to deficits in attention, verbal and non-verbal learning, short-term and working memory, visual and auditory processing, mathematic problem solving, processing speed, focusing on a specific topic, and motor functioning. CD is the end-point of various cardiovascular, neural, metabolic and immune function impairments. Although CD has a serious impact on patient survival and quality of life, usually it is clinically underestimated. CD is currently assessed using cognitive tests (questionnaires), which have important limitations in their diagnostic capacity, specifically in the preclinical forms of CD. Cognitive tests may not identify subclinical cases of CD but diagnose CD only when symptoms are clinically overt. Furthermore, these tests do not provide information regarding the underlying pathophysiologic background of CD. The aim of the present review is to summarize the existing literature on CD and emphasize the role of combined brain-heart magnetic resonance imaging (MRI) in its early diagnosis, before CD questionnaires are abnormal. Combined brain/heart MRI has the potential to identify patients with CD at an early stage, facilitating risk stratification and early intervention. Furthermore, in parallel with brain assessment, it provides valuable information regarding the effect of the underlying disease on the myocardium. Equipment availability, physician familiarity and cost/effectiveness should be considered before wide clinical application of combined brain/heart MRI is recommended.