Patients with VVAD experience visual comprehension problems, which cant be fixed with glasses or surgery.
Where are those darn car keys? Why cant I remember her name? Fears of Alzheimers disease have us all second-guessing even the most routine of memory lapses. Indeed, impaired memory is one of the classic early signs of Alzheimers disease.
But in a few people, memory problems arent the first sign of trouble. Instead, the first sign of Alzheimers disease is a problem with vision, or more accurately, a problem with visual comprehension. A person in the early stages of Alzheimer's disease may end up in an ophthalmologists office complaining, "I cant see, or even, "I can see, but I cant read or write. Depth perception may be off, leading to falls and other accidents.
People with these symptoms may have whats known as the visual variant of Alzheimer's disease, or VVAD. While VVAD is relatively uncommon today, it is expected to become more prevalent as the U.S. population ages and more people develop Alzheimers disease. Because the visual comprehension problems come first in VVAD, ahead of those related to memory, people who are affected may consult an ophthalmologist first, thinking that they just need new glasses or even cataract surgery.
Whenever a person claims that he or she "cant see, an ophthalmologist begins by assessing the persons visual acuity and visual fields. While some people with VVAD do show some degree of visual field loss, others have normal eye exams. In a study of eight patients with VVAD, for instance, only half had any visual field loss. Moreover, the persons visual acuity may be as good as 20/20. In other words, the problem is not that people with VVAD cant see whats in front of them, its that their brains arent accurately processing the information.
Once an ophthalmologist suspects VVAD, the individual will be referred to a neurologist for further evaluation and treatment. While the visual symptoms may be the initial -- or in rare cases, the only -- sign of Alzheimers disease, it does appear that most people with VVAD go on to develop the classic symptoms of Alzheimers disease, including impaired memory and personality changes.
Its also important to note that many people with Alzheimers disease who first experience memory problems typically develop visual problems later on. For instance, these Alzheimers disease patients often develop problems with contrast sensitivity or visual attention. Contrast sensitivity involves the ability to detect different shades of gray. Its an important consideration with nighttime driving, for instance, but it also helps us "read complex surfaces.
Visual attention has several components: It refers to our ability to detect and identify objects in space, to pay attention to two things at once, and to tune into one type of information while ignoring other less important types of information. Problems with contrast sensitivity and visual attention play a role in the early stages of Alzheimers disease, such as problems with driving a car. Later on, they contribute to such well-known problems as being unable to recognize faces or navigate familiar places. As with VVAD, its important for family members to understand that the persons visual problems are part of the Alzheimers disease and cant be fixed with glasses or surgery.