Anosognosia: clinical and ethical considerations

This review considers recent findings on classical forms of anosognosia and less dramatic disturbances in self-awareness observed in various brain disorders. It also addresses issues of clinical management and ethical treatment. The study of anosognosia for hemiplegia, Anton's syndrome, and less dramatic disturbances in self-awareness in conditions such as Alzheimer's disease, mild cognitive impairment, and severe traumatic brain injury suggests its 'multifactorial' nature. Lesions in various regions of the brain may contribute to different forms of anosognosia. Animal and human studies suggest that the insular cortex plays an important role in subjective awareness of feeling states, and may be implicated in various forms of anosognosia. Also, right frontal lobe lesions have been implicated, but typically in patients who have bilateral cerebral dysfunction. These patients require careful clinical management in light of their reduced awareness of their neurological and neuropsychological functions that impact daily activities. The study of anosognosia and disorders of self-awareness has expanded greatly over the past 20 years. Various patient groups may show different levels of impaired awareness or anosognosia. Guidelines for the clinical management and ethical treatment of these patients are needed, but beginning efforts have been made.