Is There an Association between Macular Degeneration and Alzheimer’s Disease or Dementia?

Photograph of retina with wet age-related macular degeneration

A team of British researchers has determined that there is no positive association between age-related macular degeneration (AMD) Alzheimer’s disease (AD) or dementia. The study findings do indicate, however, that people in England with dementia may be less likely to receive treatment for AMD.

The research, entitled Associations between Age-Related Macular Degeneration, Alzheimer Disease, and Dementia: Record Linkage Study of Hospital Admissions, was published in the November 14, 2013 issue of JAMA Ophthalmology (formerly Archives of Ophthalmology). JAMA Ophthalmology is an international peer-reviewed journal published monthly by the American Medical Association.

The authors are Tiarnan D. L. Keenan; Raph Goldacre; and Michael J. Goldacre, who represent the following institutions: the Centre for Hearing and Vision Research, University of Manchester; and the Department of Public Health, University of Oxford.

About the Research

From Age-Related Macular Degeneration, Alzheimer’s, Dementia Not Linked in Older People in

Alzheimer’s disease (AD), dementia and … age-related macular degeneration (AMD) are all strongly associated with advancing age. A very large study of patients in England has determined, however, that there is no association between having AMD and then developing dementia or AD.

Several previous studies have reported an association between AMD and cognitive impairment, based on mental state examination or word fluency scores.

AMD and AD are diseases that share environmental risk factors, including cigarette smoking, high blood pressure, and high cholesterol and other features such as the depositing of plaques in the brain. But the genetic risk factors for AMD and AD seem to be different, according to the report published by JAMA Ophthalmology, a JAMA Network publication.

A group of 65,894 patients with AMD was constructed from data in the English National Health Service. A dementia group (168,092 patients) and a reference group (more than 7.7 million people) were assembled in similar ways. Researchers measured the risk of AD or dementia following AMD and the risk of AMD following AD or dementia.

The study indicates that risk of AD or dementia after AMD was not elevated. However, the study findings indicate that patients in England with dementia may be less likely to receive treatment for AMD and several factors may contribute to this, including that patients with dementia may be less likely to get their eyes examined.

More about the study from JAMA Ophthalmology

From the article abstract:

Importance: The potential association between age-related macular degeneration (AMD) and Alzheimer disease (AD) is uncertain and has implications for understanding disease pathogenesis [i.e., development], referral, and treatments.

Objectives: To determine whether individuals admitted to the hospital with AMD were significantly more or less likely to develop AD or dementia in the following years, as well as to assess whether people with AD or dementia were significantly more or less likely to be admitted to the hospital for AMD treatment in the years following diagnosis of dementia.

Design, Setting, and Participants: An AMD cohort of 65?894 people was constructed from English National Health Service, linked hospital episode statistics from January 1, 1999, through February 28, 2011, by identifying computerized record abstracts for all people with an admission or day case care for AMD. A dementia cohort (168, 092 people) and a reference cohort (>7.7 million people) were constructed in similar ways.

Results: The risk of AD or dementia following AMD was not elevated. The rate ratio was 0.86 for AD and 0.91 for dementia. The likelihood of being admitted for AMD following AD or dementia was very low: the rate ratio was 0.04 for people with AD and 0.07 for those with dementia.

Conclusions and Relevance: These neurodegenerative conditions may share environmental risk factors and histopathologic features [i.e., microscopic examination of tissue in order to study disease]. However, considering AD and other dementia after AMD, their coexistence at the individual level is no different from that expected by chance. Our data also suggest that patients in England with dementia may be substantially less likely to receive AMD treatment. Further research is required to determine whether people with dementia receive appropriate investigation and treatment for AMD, as well as identify and address potential barriers.

VisionAware will continue to provide updates on macular degeneration and dementia research as they become available.

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