Anosognosia in neurodegenerative disease

Patients with neurological disorders are often partially or completely unaware of the deficits caused by their disease. This impairment is referred to as anosognosia, and it is very common in neurodegenerative disease, particularly in frontotemporal dementia. Anosognosia has significant impacts on function and quality of life for patients with neurodegenerative disease and their caregivers, but the phenomenon has received little formal study, especially in non-Alzheimer's (non-AD) dementias. Furthermore, few studies have attempted to systematically verify the potential role of specific cognitive impairments in producing anosognosia. As a result, the mechanisms underlying this phenomenon are poorly understood. Episodic memory likely plays an important role. In addition, the frontal lobe systems are important for intact self-awareness, but the most relevant frontal functions have not been identified. Motivation required to engage in self-monitoring and emotional activation marking errors as significant are often-overlooked aspects of performance monitoring that may underlie anosognosia in some patients. The present review offers a working model that incorporates these functions and stipulates specific processes that may be important for awareness of changes in one's abilities. Specification of the specific processes whose potential failure results in anosognosia can establish a roadmap for future studies.