Your 83-year-old grandmother is walking on uneven ground past a park. Instead of stopping to observe the park, she continues walking while her attention is drawn to the children playing on a swing set. Your grandmother, who has significant visual and hearing impairments, suddenly finds herself losing her balance and falling to the ground. Imagine yourself in that same situation, would you have fallen? Most likely, you would have carried out the two tasks (i.e., walking and maintaining balance) simultaneously without hesitation. So why then did your grandmother not have the same experience as you? The following article will discuss how the different aspects of aging work with one another and contribute to fall risk among older adults.

The process of aging is most often accompanied by reduced mobility, poorer sensory functioning, and poorer cognitive functioning. Most alarming, however, is that nearly 20-30% of older adults fall each year and falls remain the leading cause of injury-related hospitalizations among Canadian seniors [1]. A great deal of research has emphasized how each of the three factors affects fall risk on their own, but little emphasis has been placed on how interrelated these factors truly are. For example, sensory function, balance, and cognitive function all influence one another and fit together like the pieces of a puzzle. Understanding how these factors influence each other is crucial in working toward reducing fall risk among older adults.

The Impact of Sensory Loss on Balance

Sensory loss is a very important puzzle piece when understanding fall risk and balance ability among older adults. Sensory loss, specifically hearing loss, is extremely prevalent in old age, with approximately 78% of older adults between the ages of 60 to 79 years old experiencing at least mild hearing loss [1]. Of interest, older adults with hearing loss are more likely to demonstrate greater instability and an increased risk of falling [2]. This relationship also appears to be stronger with more impaired hearing. Researchers have highlighted that with every 10 dB increase in hearing loss, an individual was 1.4 times more likely to have reported a fall within the 12 preceding months [2]. Therefore, older adults with a greater degree of hearing loss are more likely to fall as they cannot safely rely on external cues. In terms of vision loss, older adults with impaired vision are much more likely to report instability and falls than their normal vision counterparts [3]. Multisensory loss is also very common in old age, with nearly 1 in 5 older adults having at least two sensory impairments (e.g., hearing and vision loss) [3]. When considering fall risk, having a greater number of impairments, such as hearing and vision loss, as well as more severe impairments, increases an older adult’s risk of falls [3].

The Impact of Sensory Loss on Cognitive Functioning

It is also important to understand the relationship between sensory loss and cognition in older adulthood. Both hearing and vision loss have been found to negatively impact cognition, whereby older adults with significant sensory impairment perform more poorly on measures of cognitive functioning [4, 5]. Why is this? Well, sensory loss appears to add a significant cognitive load, which can be thought of as an added burden or obstacle in achieving a desired goal.

The Impact of Cognitive Decline on Balance

Lastly, it is important to understand the role of cognition on balance performance. It is well known that with age, older adults have fewer cognitive resources [4]. To further understand the idea of cognitive resources, let’s consider a jar of tokens. As we get older, we have fewer tokens in the jar than we did in young adulthood. As a result, we have fewer tokens to distribute evenly among multiple tasks, creating a greater difficulty in completing seemingly simple tasks that are otherwise overlooked by younger adults. Older adults also face normal-age related decline in their cognitive functioning. As a result, you may notice that older individuals in your lives may not have as sharp a memory as they used to, may struggle with dividing their attention, and even performing two tasks simultaneously without compromising one of the performances. However, you may not attribute these memories and attentional changes to an increased risk of life-threatening falls. There is evidence to support that individuals who have a greater degree of cognitive decline are more likely to face instability and have a greater risk of falling [6]. Additionally, often as a result of normative age-related decline, older adults have a less efficient ability to effectively divide their attention between two tasks. Difficulty in dividing attention can help explain why older adults who undergo a cognitively stimulating task while simultaneously balancing often demonstrate increased postural sway (i.e., greater instability) and a greater likelihood of falling [7, 8]. Cognition directly impacts balance, meaning that older adults are less likely to perform two tasks effectively, as they must choose whether to preserve their cognition or their balance.

Returning to the previously mentioned scenario, we can conclude that visual and hearing impairments directly increased the risk of instability in your grandmother. This example illustrates that cognition can directly affect fall risk, but that sensory impairment indirectly affects fall risk by burdening the cognitive resources [4]. Cognition also indirectly played a role, as her sensory impairments added a significant cognitive load, or burden, which placed her ability to balance effectively in jeopardy. Lastly, her age alone meant that she may be experiencing normative age-related cognitive decline and decreased executive functioning. This may have been why she struggled to observe the playground while simultaneously walking. Ultimately, it is nearly impossible to pinpoint a single reason for the fall, as it was most likely the result of a culmination of interrelated factors. Additionally, within this area of research, several other factors may influence cognition among older adults. For example, an individual’s level of education is a strong predictor of the maintenance of cognitive functioning over time [9]. Understanding what factors contribute to fall risk among older adults can be extremely important in working toward interventions to reduce their danger. Indeed, assistive devices such as hearing aids, exercise, and cognitive training programs may all work cohesively to combat the normative struggles associated with the typical aging processes and decrease the risk of life-threatening falls among older adults.

References

1. Statistics Canada. (2016). Hearing loss of Canadians, 2012 to 2015, https://www150.statcan.gc.ca/n1/pub/82-625-x/2016001/article/14658-eng.htm

2. Lin, F. R., & Ferrucci, L. (2012). Hearing loss and falls among older adults in the United states. JAMA Internal Medicine, 172(4), 369-372.

3. Alfaro, A.U., Guthrie, D.M., McGraw, C., & Wittich, W.(2020). Older adults with dual sensory loss in rehabilitation show high functioning and may fare better than those with single sensory loss. PLOS ONE, 15(8). https://doi.org/ 10.1371/journal.pone.0237152

4. Guerreiro, M.J., & Van Gerven, P.W.M. (2017). Disregarding hearing loss leads to overestimation of age-related cognitive decline. Neurobiology of Aging, 56, 180-189. https://doi.org/10.1016/j.neurobiolaging.2017.05.001

5. Liu, C., & Lee, C.T. (2019). Association of hearing loss with dementia. Neurology, 2(7).https://jamanetwork.com/journals/jamanetworkopen/article-abstract/2740068

6. Tangen, G.G., Engedal, K., Bergland, A., Moger, T.A., & Mengshoel, A.M. (2014). Relationships between balance and cognition in patients with subjective cognitive impairment, mild cognitive impairment, and Alzheimer’s disease. Physical Therapy, 94(8), 1123-1134. https://doi.org/10.2522/ptj.20130298

7. Doumas, M., Smolders, C., & Krampe, R.T. (2008). Task prioritization in aging: effects of sensory information on concurrent posture and memory performance. Experimental Brain Research, 187, 275-281. https://doi.org/ 10.1007/s00221-008-1302-3

8. Huxhold, O., Li, S., Schmiedek, F., Lindenberger, U. (2006).Dual-tasking postural control: Aging and the effects of cognitive demand in conjunction with focus of attention. Brain Research Bulletin, 69(3), 294-305. https://doi.org/10.1016/j.brainresbull.2006.01.002

9. Van Hooren, S. A. H., Valentijn, A. M., Bosma, H., Ponds, R. W. H. M., Van Boxtel, M. P. J., & Jolles, J. (2007). Cognitive functioning in healthy older adults aged 64–81: a cohort study into the effects of age, sex, and education. Aging, Neuropsychology, and Cognition, 14(1), 40-54. https://doi.org/10.1080/138255890969483

About the Author

Alyssa Stevenson is an undergraduate student in Honours Psychology at Concordia. She recently completed her thesis on the impact of multisensory loss and cognitive load on older adults’ balance performance, under the supervision of Dr. Karen Li. Following graduation, Alyssa hopes to pursue graduate studies.