Cognitive impairment in common, noncentral nervous system medical conditions of adults and the elderly

Abstract

Common, noncentral nervous system medical conditions linked with cognitive impairment in adults and the elderly include: acute respiratory distress syndrome; cancer; chronic kidney disease; chronic obstructive pulmonary disease; coronary heart disease; hypertension; obesity (bariatric surgical candidates); obstructive sleep apnea; and type 2 diabetes. Cross-condition comparison of the nature and frequency of cognitive impairment is difficult as these conditions often coexist, and there exists no consensus as to the definition of cognitive impairment, nor the optimal number and type of neuropsychological tests required for evaluation. There is as yet no clear evidence for condition-specific profiles of cognitive impairment. Rather, a generalized profile consisting of subclinical levels of impairment in attention, processing speed, executive, and memory functions from bilateral frontal–subcortical ischemia fits across all conditions. This profile: occurs only in subgroups of patients; is inconsistently related to measures of illness severity; is unrelated to patient self-report or level of functional independence; is exacerbated by very high levels of emotional distress; and is reversible in some cases but can also progress to frank neurological disease (dementia) in others, especially the elderly, when multiple conditions coexist, and/or when medical condition severity progresses.