Abstract
Purpose: :
Vision function and some ocular disorders have been suggested to be markers of risk of dementias and cognitive decline. The purpose of this paper was to evaluate the associations between several measures of vision function, ocular disease and cognitive function in two cohorts.
Methods: :
The Mini-Mental State Examination (MMSE) was obtained in 1998-2000, 2003-05 and 2009-10 as part of the follow-up examinations of the Epidemiology of Hearing Loss Study (EHLS). During the 2009-10 visit additional measures of cognitive function (Trail Making Test (TMTA and TMTB) and the Auditory Verbal Learning Test (AVLT)) were obtained. Monocular visual acuity (VA, impaired= 20/40 or worse), Pelli-Robson Contrast Sensitivity(CS, impaired<1.55 log units), and cataract and age-related macular degeneration (AMD) were measured in the 1998-2000 Beaver Dam Eye Study (BDES) examinations. There were n=2361 participants with normal cognition in 1998-2000 and vision data. As part of the Beaver Dam Offspring Study (BOSS; n=3285; mean age 49 yrs) similar measures of vision and cognitive function (MMSE, TMTA, TMTB, and the Grooved Pegboard (GP)) were obtained in 2005-08.
Results: :
In the EHLS/BDES cohort, impaired CS was significantly associated with the 10-yr incidence of cognitive impairment (Hazard Ratio = 1.79, 95% Confidence Interval=1.24,2.58), adjusting for age, sex and education. VA, cataract and AMD were not associated with risk of cognitive impairment. CS was associated with age-sex-education-cataract adjusted performance ten years later on TMTA and TMTB (but not with AVLT scores). CS was associated with the score on non-vision-dependent items of the MMSE (p<0.006) ten years later. In the BOSS, VA, CS and cataract were associated with longer times on TMTA, TMTB and GP (p<0.001) but not with MMSE score.
Conclusions: :
There are strong cross-sectional and longitudinal associations between vision measures and cognitive dysfunction suggesting they may be markers of brain changes in aging or shared risk factors. However, these associations may partially reflect the vision-dependent nature of many cognitive tests. The utility of visual system changes as early markers of risk of cognitive impairment remains to be determined.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • aging