More than 60 percent of people with Alzheimer's disease will experience a decline in some visual capacity, most commonly in motion blindness, depth perception, color perception and contrast sensitivity.

With motion blindness, people are unable to sense movement. They perceive the world more as still frames rather than fluid movement. Those with depth perception problems see 3-D objects as flat, causing them to see shadows or perceive dark rugs as holes.

Visual capacity in color perception declines with age; however, people with Alzheimer's disease experience a greater deficit of color perception, mostly with colors in the blue-violet range. Contrast sensitivity is also reduced in people with Alzheimer's. They lose the ability to see the color and also the contrast between colors. For instance, they might have difficulty finding a toilet in a bathroom that has the same color toilet as the walls and floors.

A diagnosis at a young age might mean the person has posterior cortical atrophy. This form of dementia, often affecting people in their 50s and 60s, is easy to overlook; key components are usually vision problems without any discoverable eye disease, combined with mild cognitive decline in the beginning stages of Alzheimer's.

First discovered in 1902 by neurologist Arnold Pick, PCA is likely to be present in about one in every 20 people with dementia. The damage with PCA is especially severe in the posterior part of the brain that houses the occipital lobes, which helps us understand what we see.

People experiencing PCA may have trouble distinguishing objects, picking out things from a clutter of other objects. Additionally, people with PCA will show some significant behavioral changes, such as anxiety, irritability, apathy and depression. Though no medications have been proven to be effective for PCA, physicians often prescribe common ones used for Alzheimer's, such as Aricept, Namenda or Exelon.

For those with PCA, home modifications are critical. Clutter should be removed, and bright labels should be applied to objects, windows and glass doors. Adequate lighting, with attention to reducing glare, is also most helpful.

Researchers have found plaques and tangles in the occipital lobes and other brain areas typical for Alzheimer's in autopsies of individuals with PCA as well as oftentimes discovering corticobasal degeneration related to dementia with Lewy bodies. Brain imaging and measuring brain metabolism are important analyses in establishing a definitive diagnosis of PCA.

Questions about Alzheimer's disease or a related disorder can be sent to Dana Territo, the Memory Whisperer, director of services at Alzheimer's Services of the Capital Area at or visit the organization at 3772 North Blvd., Baton Rouge.