What is agnosia and what causes it?

Agnosia is a disorder in perception. The person can’t recognize objects, shapes or people. A person with agnosia is not able to comprehend the meaning of what they see and cannot recognize objects, shapes or people. For example, the person may run into furniture, believe a spouse is an impostor, become frightened by ordinary sounds, or fail to recognize their own reflection in a mirror. Agnosia can contribute to inappropriate behavior. It can occur in people with Alzheimer’s disease and other dementias, after a stroke or other less common brain diseases.