The researchers behind the current study believe that vision is the stronger factor in the association and have also said that their study is the first to show this relationship. The true causation behind the correlational decline in vision and cognitive function in the elderly is yet unknown, however.
This study took the form of a prospective longitudinal population-based analysis. The participants for the study consisted of 2,520 community-residing adults in Maryland. They were ages 65 to 84 at the outset of the population sample. On average the participants were 73 years old and 58% were women. The study had a follow up period of 8 years, during which the researchers measured visual acuity and cognitive function.
They noted that cognitive decline increased from 11% at the outset of the analysis to 20.6% at the end of the follow up period. Visual acuity also declined in the participants from the outset of the experiment through the 8-year follow up. The researchers also found a significant correlation between the rates of decline of visual acuity and cognitive function. A lower visual acuity score was correlated with a lower cognitive function score and the worse the decline in visual acuity was, there was an equal decline in cognitive function.
Vision a stronger influence on cognition than vice versa
Through comparisons of the visual acuity score at the beginning of the study with the cognitive function score, as well as scientific calculation, the researchers determined that visual acuity was the more dominant factor in the relationship. Meaning, the decline of visual acuity had a much stronger effect on the associated decline in cognitive function than vice versa. One hypothesis for the causation behind this is that visual impairment limits one’s ability to perform quality-of-life activities that benefit physical, mental, and emotional well-being, naturally causing additional stress to one’s cognition.
The researchers concluded by saying that if visual impairment were the driving factor in the association between the two, protecting vision and preventing vision loss in the elderly could be the most effective method of decreasing rates of vision loss and cognitive decline in this population globally.
They caution medical practitioners, however, that early intervention into vision loss should only be followed through if there is evidence that it will truly prevent further visual impairment or cognitive function. Until there is a fully viable treatment path, it should not be attempted for the sake of the patient. The researchers also note that if a solution for the optimization of vision were achieved, it may in itself stave off cognitive decline as a naturally occurring part of aging.
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