Posterior cortical atrophy (Benson's syndrome) is a rare condition that is considered a variation of Alzheimer's disease. It is known as a visual variant, meaning it primarily affects an individual's vision, and it may impact cognitive function as it progresses as well. Approximately five percent of Alzheimer's disease patients have posterior cortical atrophy. In addition to Alzheimer's disease, posterior cortical atrophy may occur with Lewy body dementia and some other progressive neurological conditions. Typically, the first symptoms begin in patients in their fifties and sixties. Since the initial symptoms are subtle, proper diagnosis is often delayed. To diagnose posterior cortical atrophy, doctors begin with a physical examination, mental status exam, and a neurological exam. Patients may also have an ophthalmic exam, blood tests, and MRI, PET, or SPECT scans. Although posterior cortical atrophy cannot be cured, treatments are available to slow the progression of the disease and improve quality of life. Medications, physical and occupational therapy, support groups, and home modifications are all recommended to help patients with this condition.
Some of the most common symptoms seen in patients with posterior cortical atrophy are discussed below. Many of these symptoms are often attributed to less serious conditions, so it is important that patients who notice any of these signs receive a prompt medical evaluation.
Blurred vision generally begins in the early stages of posterior cortical atrophy, and it is often the first symptom patients notice. As the condition progresses, vision may become increasingly blurry for prolonged periods. Patients might have trouble reading street signs, newspaper articles, or messages on the computer, and they may have particular trouble reading fine print. Blurry vision may cause patients to struggle to identify objects and faces, both in real life and in photographs. For patients with posterior cortical atrophy, receiving stronger glasses or contacts does not alleviate the blurred vision; this is because it is not the eyes that are damaged. Rather, the blurred vision is caused by the changes posterior cortical atrophy creates in the brain itself. To help make life with blurry vision easier, patients may need to change the lighting in their homes to make sure it is bright enough, and particular attention should be paid to reducing glare. Placing stickers or signs on glass windows and doors can allow patients to see these more clearly.
Sensitivity To Light
Sensitivity to light is another early symptom of posterior cortical atrophy. In the beginning, patients may be more sensitive to bright lights, including flashlights, lights in the bathroom, and bright sunlight. Doctors can evaluate the degree of a patient's sensitivity to light with a comprehensive eye exam. As posterior cortical atrophy advances, patients may have a reduced tolerance for other types of light that are not particularly bright. For some individuals, light sensitivity may be accompanied by headaches. To reduce this sensitivity, patients may wish to wear sunglasses (both outdoors and inside the home), and they might want to install lights with dimmer systems to adjust brightness. Curtains may be helpful as well. In addition to light, some patients may be sensitive to shiny objects, and choosing items with a matte finish may be beneficial.
Visual agnosia was first identified in 1890, and it refers to the patient's inability to recognize people and objects using sight alone. Some patients may have a total loss of visual recognition, and others may be only partially affected. The type of visual agnosia associated with posterior cortical atrophy is known as secondary visual agnosia. Patients with this form of agnosia may be unable to recognize pictures of identical objects taken from different angles, and they may have difficulty drawing a picture of a familiar object. Some patients might be unable to state how objects they see in photos are normally used. Patients with this ailment often use touch, smell, or sound to identify objects, and they may identify others based on how they walk or talk. Medications used to treat Alzheimer's disease may help patients with posterior cortical atrophy in identifying objects and people more easily. Sometimes, patients might choose to have rehabilitation that re-teaches them about commonly used objects, and therapy used to restore lost memories may also be beneficial.
Depth Perception Issues
Depth perception issues frequently cause posterior cortical atrophy patients to have trouble with driving. In most cases, trouble with depth perception can make it too dangerous for these individuals to drive safely, and many choose to give up their driver's licenses voluntarily. Depth perception problems are often accompanied by double vision, and some patients may have trouble telling the difference between whether an object is moving or stationary. An inability to perceive more than one object at a time is also common. Some posterior cortical atrophy patients may feel disoriented, and hallucinations have been reported as well. Since depth perception difficulties may affect an individual's ability to maintain an active and independent lifestyle, patients can experience mood changes, including irritability and anxiety. To minimize difficulties and hazards associated with reduced depth perception, patients with posterior cortical atrophy should be very careful when using stairs, and throw rugs in the home may need to be removed or reinforced with non-skid padding to reduce the risk of falls.
Decline in Literacy Skills
The vision issues and cognitive changes that are part of advanced posterior cortical atrophy may lead to a decline in literacy skills. Patients may have trouble reading, and spelling difficulties might also develop. The patient's ability to work with numbers and perform mathematical calculations may be reduced. Individuals with posterior cortical atrophy could also experience trouble with finding familiar words. To assist patients who have declining literacy and numeracy skills, caregivers may wish to read texts to them, and they can also assist with reading the mail and with writing checks and paying bills. Posterior cortical atrophy patients may need help with counting money while shopping as well. Medications that reduce cognitive decline and other treatments that ease anxiety and depression may help patients with this symptom feel better.