Multisensory loss may up dementia risk
Multisensory dysfunction is tied to an increased risk of developing dementia or Alzheimer’s disease (AD) in older adults, thus underlining the importance of sensory evaluation in this patient subgroup and among those at risk of developing neurodegenerative illnesses, according to studies presented at AAIC 2019.
The link between vision/hearing impairment and risk of all-cause dementia and AD was evaluated using data from the Gingko Evaluation of Memory cohort, which comprised 2,827 adults aged ≥75 years who did not have dementia at enrolment. [AAIC 2019, abstract O1-02-05]
Compared with those without sensory impairment, the risk of all-cause dementia and AD was higher among those with single (adjusted hazard ratio [adjHR], 1.27, 95 percent confidence interval [CI], 1.02–1.59 for all-cause dementia and adjHR, 1.29, 95 percent CI, 1.02–1.62 for AD) and dual sensory impairment (adjHR, 1.70, 95 percent CI, 1.18–2.45 for all-cause dementia and adjHR, 1.69, 95 percent CI, 1.15–2.49 for AD).
Overall, the number of sensory impairments was associated with the risk of all-cause dementia and AD in a graded fashion (p<0.001 for both).
The findings demonstrate the impact of co-occurring hearing and visual impairments in the development of dementia, said study author Phillip Hwang, a doctoral student in epidemiology at the University of Washington in Seattle, Washington, US. “Impairment of more than one sense seems to increase risk of dementia synergistically.”
Another study evaluating the combined effect of multisensory (ie, smell, touch, vision, and hearing) impairment on the development of dementia and AD found a strong association between higher multisensory scores – which signify a greater level of impairment – and an increased risk of dementia in a graded fashion (HRs, 1.20; p<0.05, 1.53; p<0.05, and 1.96; p<0.001 for multisensory score quartiles 5–6, 7–8, and 9–12, respectively). [AAIC 2019, abstract P1-618]
Even a mild multisensory impairment was strongly linked to the risk of developing dementia, as the four-point score difference (out of 12 points) generated a 68 percent increase in dementia risk (adjHR, 1.68, 95 percent CI, 1.31–2.01).
Given the association between dementia/AD and sensory impairment even at mild levels, evaluating alterations in multisensory function is imperative to help identify older adults at high risk of developing dementia, said study author Dr Willa Brenowitz from the University of California, San Francisco in San Francisco, California, US. “Sensory function in multiple domains can be measured during routine healthcare visits using noninvasive or minimally invasive tests.”
Moreover, as some forms of hearing and vision loss are treatable, this opens a channel for intervention, noted Brenowitz. “[M]ore research [is warranted] to determine if treatment or prevention of sensory impairments could reduce risk of dementia,” she added.