Cataract Surgery May Slow Cognitive Decline

Abstract

Cataract surgery not only improves visual acuity in individuals with Alzheimer's disease and other dementias – it also appears to slow cognitive decline and improve neuropsychiatric symptoms, according to preliminary results from an ongoing study. An initial analysis comparing 28 surgical and 14 nonsurgical patients – about a third of whom were nursing home residents – is currently being expanded. “If these results hold up (with a larger study population), we will definitely see changes in practice,”Alan Lerner, MD, professor of neurology at Case Western Reserve University School of Medicine, who presented the findings at the Alzheimer's Association International Conference 2014, told Caring for the Ages. Currently, there is “tremendous reluctance and ambivalence” toward treating comorbidities in patients with Alzheimer's and other dementias,” he said. Yet the findings – including improvements on the Mini-Mental State Exam (MMSE) and the Neuropsychiatric Inventory (NPI) among surgical patients – demonstrate that “improving vision is a clear quality-of-life issue” for these individuals, said Dr. Lerner. “Yes, Alzheimer's is a brain disease, but we have to look at the whole person. There are other factors, including vision, that affect cognition,” he said. “And the effect of visual improvement on [behavior] – it's huge.” Cataracts can be even more troublesome in individuals with Alzheimer's than in those without the disease. Grover C. Gilmore, PhD, professor of psychology and social work, and dean of the Jack, Joseph and Morton Mandel School of Applied Social Services at Case Western Reserve, has shown in other research that patients with Alzheimer's disease commonly experience significant declines in contrast sensitivity in as little as 6 months after their diagnoses – impairments that he said may result from cellular disease-related changes in the vision system. “When you put a cataract on top of this, it becomes [even more serious],” said Dr. Gilmore, the study's lead investigator. Patients included in the current study of cataract surgery met the criteria for Alzheimer's disease or other neurodegenerative dementias and had at least one visually significant cataract. They either had surgery following enrollment and baseline testing (intervention group), or refused or delayed surgery (the control group). At 6 months, scores on the MMSE had improved by a mean of 0.39 points in the intervention group and declined by a mean of 2.31 points in the control group. The average annual rate of change in MMSE scores in this population is 2–3 points, Dr. Lerner said. As important – if not more – was a decline in the NPI, which assessed anxiety, confusion, depression, and other symptoms. The mean change in the NPI was −4.91 among individuals who had cataract surgery and +3.92 among those who declined or delayed the surgery. Caregivers also benefited from cataract surgery. Caregiver distress as measured by the NPI Caregiver Distress scale declined in the intervention group and increased in the control group. Cognitive function was assessed with the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) as well as the MMSE, but the investigators found only “trending” differences in the 6-month ADAS-cog scores rather than a clear reduction in cognitive decline after surgery – a finding that Dr. Lerner attributed to the small size of the study. Unease with cataract surgery in patients with Alzheimer's disease and other dementias often involves concern about anesthesia and the general stress of undergoing a procedure, but consideration of safety and risks must be better balanced with attention to the benefits, Dr. Lerner said. “In Alzheimer's disease,” said Dr. Gilmore, “hidden visual deficits can masquerade as hidden cognitive deficits. One reason (individuals with the disease) do poorly in neuropsychological tests is that they can't see very well. “If you want to know what the world looks like to patients with Alzheimer's disease, put on two pairs of heavy sunglasses and squint,” he said. When cataracts are diagnosed, surgical intervention can “benefit vision, cognition, and quality of life,” Dr. Gilmore said. Other ocular comorbidities that can affect vision – such as macular degeneration and end-stage glaucoma – should be ruled out by an ophthalmologist before cataract surgery is seriously considered, Dr. Lerner noted. The study was funded by the National Institute on Aging. Participants were recruited from the University Hospitals Case Medical Center and MetroHealth Medical Center.