Visual symptoms in neurodegenerative dementias

Yoshiyuki Nishio¹⁾, Wataru Narita²⁾

¹⁾Department of Psychiatry and Neurology, Tokyo Metropolitan Matsuzawa Hospital
²⁾Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine

Visual deficits and false visual perception differ in their underlying pathophysiology, which is associated with functional impairment of visual cortices and aberrant cortical states, respectively.　Visual deficits are categorized into two types of symptoms that have distinct neuroanatomical correlates:visuoperceptual deficits, which arise from damage to the ventral visual pathway, and visuospatial deficits, which arise from damage to the dorsal visual pathway.　Neurodegenerative conditions whose primary clinical manifestations are visuoperceptual and/or visuospatial deficits are called posterior cortical atrophy (PCA).　Alzheimer's disease is the most common underlying neuropathology of PCA.　False visual perception, including visual hallucinations and illusions, are diagnostic signposts of Lewy body dementia.　The Pareidolia Test, which is a neuropsychological task to evoke and quantitate visual hallucination-like illusions, is a promising surrogate indicator of visual hallucinations.

Address correspondence to Dr. Yoshiyuki Nishio, Department of Psychiatry and Neurology, Tokyo Metropolitan Matsuzawa Hospital (2-1-1 Kamikitazawa, Setagaya-ku, Tokyo 156-0057, Japan)