Dual-Sensory Impairment: When 1+1=3

Abstract

The American psychologist and architect of Maslow’s Hierarchy of Needs, Abraham Maslow, is credited with the expression, “If all you have is a hammer, everything looks like a nail.” 1 We can extend Maslow’s observation to: “If all you have is a set of headphones, everything looks like a pair of ears.” As hearing care specialists, we are often so focused on the ears that we neglect the other pair of sensory organs staring right at us—the eyes. Indeed, the same demographic that experiences age-related hearing impairment (presbycusis), is likely to also experience age-related vision impairment (presbyopia). This coexistence of hearing and visual impairments is known as dual-sensory impairment, or DSI. Most of us are aware of the growing literature that supports a relationship between hearing loss and other health conditions, such as depression, falls, cognitive impairment, and dementia. Age-related vision impairment has been associated with an increased risk of experiencing some of these same disorders. 2Figure 1: Trajectories of cognition scores by the presence of any sensory impairment in the 2015 China Health and Retirement Longitudinal Study. Source: Rong, H., Lai, X., Jing, R., Wang, X., Fang, H., Mahmoudi, E. (2020). Association of sensory impairments with cognitive decline and depression among older adults in China. JAMA Network Open, 3(9):e2014186. https://doi.org/10.1001/jamanetworkopen.2020.14186HOW COMMON IS DSI? What we know about the prevalence of DSI largely depends on the measures used to identify it. Some prevalence data are based on objective measures such as audiometry or the Snellen chart, while others rely on self-reported or functional measures of hearing and vision impairment. One study conducted in the United States using objective measures 3 estimated the prevalence of DSI in older adults at 3% increasing to 12% among those 85 years of age and older. WHAT ARE THE CONSEQUENCES OF DSI? DSI has been associated with increased risks of dementia, depression, social anxiety, falls, and death. Given that either hearing or vision impairment increases the risks of many of the same disorders, it shouldn’t come as a surprise that DSI, compared with a single sensory impairment, may further increase the risks associated with these conditions. For example, investigators in South Korea followed over 6,500 individuals with DSI as part of a longitudinal study on cognitive aging and dementia. 4 At baseline, DSI was positively associated with dementia prevalence compared with those with normal sensory function. Over the six-year follow-up period, DSI was associated with higher odds of dementia incidence than hearing or visual impairment alone. In a similar study conducted in the United States, researchers followed over 7,500 Medicare beneficiaries who self-reported vision or hearing impairment. 5 Data collected after seven years indicated that those with DSI were at greater risk for developing dementia than those with hearing or vision impairment only. The consequences of DSI extend well beyond cognitive impairment. Pardhan et al. 6 researched the impact of DSI on depression and chronic anxiety among 23,089 adults participating in the Spanish National Health Survey of 2017. The researchers analyzed self-reported vision, hearing, depression, and chronic anxiety and found that vision or hearing impairment was significantly associated with higher odds for depression (OR = 2.37, 95% CI = 2.04 – 2.75 and 2.1, 95% CI = 1.67 – 2.64, respectively) and highest for DSI (OR = 3.86, 95% CI = 2.72 – 5.44). Visual or hearing impairment also increased the odds of chronic anxiety (OR = 1.98, 95% CI = 1.7 – 2.32 and 1.94, 95% CI = 1.54 – 2.46, respectively) and were highest for DSI (OR = 3.38, 95% CI = 2.38 – 4.82). Cosh et al. 7 also found a significant association between DSI and depression and anxiety as part of a longitudinal examination of a Norwegian population-based database. Rong and colleagues examined the effects of vision, hearing, and DSI on both depression and cognition among over 18,000 individuals followed as part of the China Health and Retirement Study. 8 While both vision and hearing impairment were independently associated with greater depression and poorer cognition, the combination of impairments resulted in the poorest outcomes. Figure 18 illustrates the consequences associated with visual impairment only, hearing impairment only, and DSI on global cognition scores as a function of age. DSI was associated with a greater risk of cognitive impairment among individuals of all ages followed in the study until about the age of 85 where hearing impairment alone and DSI posed a similar risk. Gopinath and colleagues 9 collected data from 1,478 participants in the Blue Mountains Eye Study to determine the association between DSI and incidence of falls. Individuals with best corrected visual impairment and mild hearing loss had a greater than twofold risk of falls over the five-year period of the study. DSI also appears to be associated with a greater risk of all-cause mortality than either vision or hearing impairment alone. The AGES-Reykjavik Study 10 involved over 4,900 Icelandic individuals enrolled in a large epidemiological study who received hearing examinations between 2002 and 2006 and who were prospectively followed for mortality through 2009. It turned out that individuals with hearing loss or visual impairment had a higher risk of death resulting from cardiovascular disease than those without hearing or visual impairment; and those with DSI had a higher risk of mortality than those with only hearing or vision impairment. Similarly, Tan et al. 11 conducted a systematic review of studies that examined the relationship between hearing loss and DSI with mortality. The investigators analyzed the results of 27 studies that met their inclusion criteria (14 retrospective and 13 prospective study designs representing a total of 1,213,756 participants). Their analysis revealed that, compared with those with normal hearing and vision, participants with DSI had a significantly higher risk (i.e., hazard ratio; HR) of all-cause mortality (HR = 1.40, 95% CI = 1.30 – 1.51) and, specifically, cardiovascular mortality (HR = 1.86, 95% CI = 1.31 – 2.65). Extending the consequences of multisensory impairment to other modalities (smell and taste, in addition to vision and hearing), Liljas and colleagues 12 found that quality of life decreased, and depression increased as the number of impaired sensory modalities increased among a sample of 6,147 individuals in the English Longitudinal Study of Aging (May 2016 – June 2017). Not surprisingly, those reporting three to four sensory impairments experienced the poorest quality of life. WHAT ARE THE IMPLICATIONS OF DSI FOR HEARING CARE PROFESSIONALS? Your older patients will likely have multiple chronic conditions, so consider the following: Update your intake forms to include questions related to comorbid conditions associated with hearing and vision impairment. Ask your patients when they last had their eyes examined or eyeglass prescription updated. Screen your patients for visual impairment. Ask your older patients to read something out loud (e.g., a sample from one of your patient education brochures or a hearing aid user manual). Develop and build relationships with vision care specialists in your community. Continue to educate yourself concerning chronic conditions associated with hearing, vision, and dual-sensory impairment to include cognitive impairment, depression, anxiety, and falls.