Visual field defects as early symptoms of Alzheimer's disease.

Abstract

Visual variant Alzheimer's disease (vvAD) is a subgroup of progressive degenerative dementia that begins with visual behavioral function. Unlike typical AD, visuospatial symptoms manifest before cognitive impairment in vvAD. 5% of AD are categorized as vvAD and right hemisphere is more affected than left. We report two patients presented with visual blur in near vision and right homonymous hemianopsia as initial symptoms who were diagnosed visual variant AD. 61-year-old man and woman presented with progressive visual disturbance. They reported persistent difficulty in reading letters in books and difficulty to take lane position while driving. Both patients showed right sided homonymous hemianopsia by visual field test. Neuropsychological test revealed impairment in general cognitive function, especially in visuospatial function, visual and verbal memory. Brain MRI did not show asymmetry but brain SPECT and FDG-PET showed hypoperfusion and hypometabolism more pronounced on left parieto-occipital area. Both patients showed β-amyloid deposition on PET scanning. Neurodegenerative disorders such as visual variant AD should be considered in patients with unexplained visual complaints. Early differential diagnosis of vvAD can lead to a better prognosis and help with early treatment.