Cataract surgery can improve cognitive ability in patients with mild Alzheimer's disease, it has been found.
Researchers at Tenon Hospital, Paris, France, say that patients whose vision improved after cataract surgery also showed improvement in cognitive ability, mood, sleep patterns and other behaviors. Lead researcher Brigitte Girard, MD, will discuss her team's results today at the American Academy of Ophthalmology's 2011 Annual Meeting.
This is the first study to specifically assess whether cataract surgery could benefit Alzheimer's patients, although earlier research had shown that poor vision is related to impaired mood and thinking skills in older people and that cataract surgery could improve their quality of life. Thirty-eight patients, average age 85 and all exhibiting mild dementia due to Alzheimer's disease, completed Dr. Girard's study. All participants had debilitating cataract in at least one eye and were appropriately treated with standard cataract surgery and implantation of intraocular lenses, which replace the eyes' natural lenses in order to provide vision correction. After surgery, distance and near vision improved dramatically in all but one of the Alzheimer's patients.
A neuropsychologist assessed the Alzheimer's patients for mood and depression, behavior, ability to function independently, and cognitive abilities at one month before and three months after cataract surgery. Cognitive status, the ability to perceive, understand and respond appropriately to one's surroundings, improved in 25 percent of patients. Depression was relieved in many of them, and the level of improvement was similar to what commonly occurs after cataract surgery in elderly people who do not have dementia. No changes were found in patients' level of autonomy, that is, their ability to function independently.
Sleep patterns improved and night time behavior problems decreased in most study patients. Other studies have shown that when cataracts are removed, levels of the sleep-regulating hormone melatonin become normalized. Dr. Girard notes that this may have been a key factor in the Alzheimer's patients' improved sleep patterns.
"We wanted to learn whether significant vision improvement would result in positive mood and behavior changes, or might instead upset these patients' fragile coping strategies," said Dr. Girard. "In future studies we intend to learn what factors, specifically, led to the positive effects we found, so that we can boost the quality of life for Alzheimer's patients, their families and caregivers."