20Q: The Importance of Cognitive Assessment in Audiology Practice

From the Desk of Gus Mueller

It seems that each year, we read more and more about the prevalence of cognitive decline in the general population, and predictions are that the occurrence of these disorders will increase substantially in the near future. This hits home with audiologists who work with fitting hearing aids, as the typical patient is an older individual. Not surprisingly, aging is the most known risk factor for cognitive decline. Another factor, however, further linking cognitive disorders to audiology is that some research has suggested that hearing impairment also is a risk factor.  Whether this can be mitigated through the use of hearing aids is under study.

All in all, it’s clearly important for audiologists to routinely consider the cognitive abilities of their patients. At the least, it will assist in patient counseling, and in some cases, it might influence treatment strategies. This topic is not new to 20Q, as we reviewed the importance of cognitive assessment in clinical audiology in an article back in 2012. That article was written by Pamela Souza, PhD, and she is making a return visit this month to fill us in on all the developments in this important area that have occurred over the past seven years.

Dr. Souza is Professor; Associate Chair, Department of Communication Sciences and Disorders at Northwestern University. She is a Fellow of the American Speech-Language-Hearing Association and serves on the Psychoacoustic and Perception Technical Committee of the Acoustical Society of America (ASA). Her research has been supported by numerous grants from the National Institutes of Health, and her publications are internationally known.

Dr. Souza directs an active laboratory whose members study aspects of aging, cognition, and speech perception, including how individual hearing and cognitive abilities affect response to hearing aid signal processing, communication in adverse (reverberant and noisy) environments, and the benefits of auditory training.

Pam also is active as a clinician and recently has focused on cognitive aspects of hearing aid fitting including listening effort and customized-for-cognition signal processing.  She tells us that she enjoys working with patients who have been unsuccessful users of amplification because of the challenge of tracking down and solving their problems. After reading this excellent article, I suspect that you too will be able to better solve some of the problems of your patients.

Gus Mueller, PhD
Contributing Editor

 

Browse the complete collection of 20Q with Gus Mueller CEU articles at www.audiologyonline.com/20Q

20Q: The Importance of Cognitive Assessment in Audiology Practice 

Learning Outcomes 

After this course, readers will be able to:

• Define abnormal cognition, mild cognitive impairment (MCI), and dementia, and explain how they may interact with hearing loss to impact understanding.
• Explain the rationale for cognitive screening in audiology, and describe a practical, clinic-friendly process for cognitive screening, counseling, and referral.
• Describe the role of working memory in hearing/understanding, and how hearing aids/assistive technology may be best serve patients with hearing loss and low working memory.

           Pamela Souza

1. My patients come to me for help with their hearing! Do I really need to be thinking about cognition?

As clinicians, we spend a lot of time measuring relatively simple abilities (like detecting tones), and less time (or no time) assessing abilities that matter in more complex listening situations. Those abilities include things like focusing on one talker while ignoring the auditory input from talkers in the background, switching attention between talkers in a group conversation, and processing and recalling what you hear. All of these tasks involve “cognitive” rather than “auditory” abilities, at least in the sense that they’re controlled at higher levels in the system.   

2. I still think my patients would find it odd if I suddenly started talking about cognition rather than hearing.

Maybe, but our patients are thinking about cognition, even if we never bring up the topic. In an analysis of topics that were spontaneously raised in conversation by older patients with hearing loss, half of the patients talked about cognitive ability (Preminger & Laplante-Levesque, 2013). Those comments included memory, attention, and effort. And, about a third of older adults report a fear of developing dementia—even those who have no family history or risk factors (Kessler, Bowen, Baer, Froelich, & Wahl, 2012). 

3. Can you give me some examples of situations where my patients might be affected by their cognitive ability, in addition to their hearing loss? 

Sure. Think about a common complaint: conversation in a noisy restaurant. Certainly, background noise can be an issue if it masks the talker, but often the talker is audible and the problem is sorting out a complex auditory scene. This involves a whole set of cognitive abilities: selective attention, inhibition, processing speed, working memory, attention switching, lexical access, and recall. Another example of something patients complain about is listening in a reverberant (echoing) room, such a church, synagogue or auditorium. Very often in reverberant spaces it’s not that it’s noisy as there may be only a single person talking. However, the issue is that the sound is distorted by reverberation. Recent research tells us that when there’s no reverberation, the listener’s ability to detect changes in the speech envelope is closely associated with speech intelligibility. When there is a moderate amount of reverberation, listener age and degree of hearing loss are associated with speech intelligibility. And when there is a lot of reverberation (such as in a large auditorium), listener age and working memory capacity are associated with speech intelligibility (Reinhart & Souza, 2018). We can think of cognition as playing a larger role whenever the listener is trying to perceive a distorted or fragmented signal. 

4. Wait, I think I understand what cognition is, but what is working memory? 

You might remember from your psychology courses that memory includes long-term and short-term storage. New auditory and/or visual information is actively compared and integrated with information in our mental lexicon. In other words, there is an active two-way processing path between stored information (linguistic knowledge) and new information. So, to measure working memory, we need to think about measuring the listener’s ability to temporarily store and manipulate information.

5. Can I measure cognitive ability? Should I measure cognitive ability? And, what do I do with the results?

Not so fast. First, let’s talk about the two ways cognitive ability might play a role in the process of diagnosing and rehabilitating hearing. We can loosely think of this as two separate points where you might consider cognition: how the normal (or age-typical) patient’s cognitive ability affects communication; and screening for abnormal cognition. 

6. What exactly is “abnormal” cognitive ability?

According to the APA (American Psychiatric Association, 2013), abnormal cognition (or “neurocognitive disorder”) is a decline from a previous level of performance in one or more cognitive domains (such as attention, learning or memory). For example, forgetting where you put your keys when you came home yesterday is not concerning, but forgetting that the keys start the car is concerning. Patients with abnormal cognition include those with dementia and mild cognitive impairment (MCI). MCI is a modest cognitive decline from a previous level of performance, but one where the patient is still independent in everyday activities (although may need some new strategies to compensate). Dementia is a significant cognitive decline from a previous level of performance that interferes with independence in everyday activities. MCI sometimes, but not always, progresses to dementia (Langa & Levine, 2014; Winblad et al., 2004). In the typical audiology practice, we are more likely to see patients with MCI than dementia, both because MCI is less likely to have been brought to the attention of the patient’s primary care provider (Chodosh et al., 2004) and because patients with MCI make up a large proportion of some age groups. For example, as many as 20% of patients over 60 years may have mild cognitive impairment (Petersen, 2016)—the very age group that accounts for the majority of patients in most audiology clinics. 

7. Why should I, as an audiologist, be concerned with MCI? Isn’t testing for that the responsibility of the primary care physician?

That depends. Physicians who conduct annual wellness exams with Medicare patients are asked to assess cognition (Medicare Learning Network, 2018) but that directive doesn’t necessarily mean they will conduct formal screening. And a typical physician visit is likely to be short, to focus most of the time on the patient’s primary complaint (such as monitoring an existing health condition), and to leave only a few minutes, at most, for other concerns to be raised (Peckman, 2016). Because audiologists spend more time with their patients over the course of multiple visits (such as a hearing aid evaluation, fitting, and follow-up) this is an opportunity to be alert to cognitive issues requiring a referral.  

8. In that case, what test should I use?

First, let’s remember that all of these “tests” are really screening instruments, not diagnostic instruments. They only identify the need for further assessment (much as a hearing screening done at a health fair would identify the need for a full audiological evaluation). There are many choices, depending on how much time you have. The Montreal Cognitive Assessment or MoCA (https://www.mocatest.org) (Nasreddine et al., 2005) takes about 10 minutes, is well-validated and sensitive to MCI. If you don’t have 10 minutes, the Mini-Cog (https://mini-cog.com) (Borson, Scanlan, Brush, Vitaliano, & Dokmak, 2000) is another well-validated test that takes about 3 minutes to administer. If you don’t have 3 minutes to spare you can get some sense of cognitive ability with a single test item, such as the clock drawing item; or just be alert to referral needs drawn from concerns expressed by the patient, or that you notice yourself. 

9. If someone “fails” the screening, what should I do then?

The first step is a conversation with the patient about the results. In my experience, patients who fail a cognitive screening have often noticed cognitive issues, such as forgetting more than they think they should. One way to begin the conversation is by asking if they have had any concerns about their memory. It’s also important to remind them that the screening is not a complete evaluation or diagnosis, just something that should be explored. Remember that this is a very emotionally charged issue, and the fear of memory loss is powerful. Listen, be empathetic, and don’t discount your patient’s concerns. That conversation should naturally lead to some action, usually in the form of referral to a professional who can do further evaluation. That may be the patient’s primary care physician, a geriatrician, a psychologist, or a neurologist. Which one is appropriate depends on the patient, their existing medical team, and on your practice structure (for example, audiologists who practice within large medical centers may have an established referral pathway for such concerns). Finally, in your referral letter to the physician, treat the cognitive screening results as you would any other information you provide. Provide the details of the screening measure you used, the patient’s score, and any relevant history (such as concerns expressed by the patient or patient’s family members) to support appropriate care after referral. 

10. Should I be testing everyone for MCI?

That’s one option, but it may be a challenge to allocate enough appointment time, avoid over-referral from false positive results, and counsel all patients appropriately on the need for the test and the results. 

11. That doesn't sound very practical. Are there any other options?

Yes. In a 2008 review paper, Akeroyd (2008) surveyed 20 studies of communication and cognition and found that working memory was the strongest predictor of communication difficulty in noise. Simply put, working memory is the ability to process and store information. But before you decide to measure working memory, let’s talk about why it affects communication, using something called the Ease of Language Understanding (ELU) Model (Rönnberg et al., 2013). Think about a listener having a conversation. That listener is receiving a sequence of auditory cues that include phonology, semantics, syntax, and prosody. Under ideal conditions, such as speech in quiet to a listener with normal hearing, all of the incoming auditory information is clear and audible, and can be rapidly matched to a stored representation in long-term memory. So if you say, "hit the ball" I quickly picture a baseball and bat (or a tennis racket, etc.) and I don't need to work very hard to assign meaning to that statement. Under distorted conditions (such as noise, reverberation, degraded input from an impaired auditory system or all of these at once), the stream of information is incomplete and cannot be easily matched to stored representations. That “mismatch” is what engages working memory. For a listener with high working memory, cognitive resources are readily available to reconcile the mismatch. But when a listener has lower working memory, the pool of cognitive resources may not be sufficient to reconcile the mismatch. And in the meantime, the talker talks on, so more information is arriving that also needs to be processed and matched to stored lexical information. No wonder people with hearing loss say they get tired when listening in noise! 

14. OK, I’ve got it. How do I measure working memory?

There are two “clinic-friendly” options for measuring working memory. One is the Reading Span Test, available in long and short versions (Ng, Rudner, Lunner, Pedersen, & Rönnberg, 2013; Rönnberg, Arlinger, Lyxell, & Kinnefors, 1989). During this test, sentence segments are shown one at a time on a computer screen (for example, “The bottle”, “drank”, “water”). The reader processes information by responding whether the sentence makes sense. After a set of 2, 3, 4, 5 or 6 sentences, the reader recalls either the first or last words of the sentences that were presented. The test score is the percent of words that were correctly recalled. 

The other option is the Word Auditory Recognition and Recall Measure, or WARRM (Smith, Pichora-Fuller, & Alexander, 2016). In the WARRM, recorded monosyllable words are presented in a carrier phrase. The listener repeats the word in the usual way, but also processes information by stating whether the first letter of the word is from the first or second half of the alphabet. After a set of 2, 3, 4, 5, or 6 words, the listener is asked to recall the words from that set. The result is the usual percent correct repetition score, plus a percent correct recall score that measures working memory. The Reading Span Test is a visual working memory test that won’t be suitable for patients with significant vision or reading disabilities. Conversely, the WARRM, which is an auditory working memory test, won’t be suitable for patients whose hearing is so poor that they have substantial difficulty hearing the recording. 

15. If I give a working memory test, how do I interpret the results? Does a patient "pass" or "fail"?

For the Reading Span Test we expect the average score for older adults to be around 40% (Souza & Arehart, 2015), and for the WARRM the average recall score for older adults with hearing loss is around 70% (Smith et al., 2016). Most research studies have divided patients into higher and lower working memory groups according to how they scored on the test. In the clinical setting, we are only going to be concerned with low working memory individuals, because those are the people likely to be at a disadvantage in difficult listening situations. So, one simple way to interpret scores in a clinical context is to consider patients who fall lower than the mean minus one standard deviation (below a score of about 30% for the Reading Span Test, and below 60% for the WARRM) to have low working memory that may impact their communication. One caution: when we give these tests, we've found it sometimes causes patients to worry about memory loss or even dementia. There is no evidence that patients with low working memory scores today are going to develop dementia in the future, so this is an important fear to allay. 

16. Right. OK, suppose I’ve identified one of my patients as having low working memory. What do I do with that information? 

We have two suggestions for how to use the information. One has to do with counseling, and one has to do with device choices. Let’s take the counseling piece first, since it’s easy to do. We all recognize that our patients want the best possible hearing aid for their needs. But they also tend to place a lot of responsibility on the hearing aid; that is, they assume if they get the “right” one they’ll hear well in all or most situations. They may not recognize that there are other aspects of the listening environment or their ability to process information in that environment that are also important. This is where we think working memory can be part of counseling, especially for patients where you expect low working memory to increase communication difficulty. I often use the terms “processing” and “memory” in my conversations, but any phrasing that helps the listener distinguish between difficulty “hearing” (receiving audible sound) and the various cognitive processes (attention, effortful listening, filling in missed information) can be used. Various resources are available to support these conversations, such as the material provided by the Ida Institute (www.idainstitute.com).

17. You mentioned device choices. How can knowing the listener’s working memory help with that?

There are accumulating data that working memory affects the way an individual responds to hearing aid processing. So far, researchers have studied three types of processing, separately and in combination: wide dynamic range compression (WDRC) speed; frequency lowering; and omnidirectional digital noise reduction. All of these are intended to improve speech sound audibility and recognition, but to do that they have to modify the signal. Fast-acting WDRC, for example, improves audibility by increasing gain for soft speech sounds. Frequency compression improves audibility by compressing higher-frequency speech sounds to a lower frequency range. Getting back to the Ease of Language Understanding model we talked about earlier: many researchers think working memory plays a role in response to signal processing whenever the signal processing modifies the speech enough to create a lexical mismatch. What the hearing aid and working memory studies showed was that, in general, listeners with lower working memory didn’t receive as much benefit as listeners with higher working memory for any processing that incidentally created a lot of signal modification (Foo, Rudner, Rönnberg, & Lunner, 2007; Lunner, 2003; Ohlenforst, MacDonald, & Souza, 2015; Souza, Arehart, Kates, Croghan, & Gehani, 2013; Souza, Arehart, Shen, Anderson, & Kates, 2015; Souza & Sirow, 2014). Greater signal modification occurs with faster WDRC speeds, higher frequency compression ratios, lower frequency compression cutoffs, or all three. Digital noise reduction is probably a special case. It is designed to remove noise components while retaining speech components, but because it can’t perfectly classify the signal, some noise components are accidentally retained and some speech components are accidentally removed. But, while aggressive digital noise reduction can distort the target speech, it also removes noise – and removal of that noise should help listeners with low working memory. That balance of mostly positive effects mixed with a few negative effects is probably why digital noise reduction was only weakly related to working memory (Souza, Arehart, & Neher, 2015). Anyway, the take-away from this research may be that, especially for listeners with low working memory, you should reduce noise whenever possible (i.e., use good directional microphone technology and a reasonable amount of digital noise reduction), then use the slowest compression speed and the least amount of frequency lowering that will accomplish your fitting goals. 

18. Weren’t these all research studies? Do they really apply to the things I do every day in the clinic?

Most of the studies either used wearable hearing aids (Anderson, Rallapalli, Schoof, Souza, & Arehart, 2018; Gatehouse, Naylor, & Elberling, 2006; Lunner & Sundewall-Thoren, 2007; Souza & Sirow, 2014) or at least designed their processing to closely mimic wearable aids, so we should be able to generalize the results to clinical use. But there are a few qualifications. In some studies, the listeners had a chance to acclimatize to the hearing aids, but in others they didn’t. At least one study has suggested that the strength of working memory as a factor declines with longer-term use of new processing (Ng et al., 2014). It may be that getting accustomed to new processing reduces the lexical mismatch and allows the listener to take better advantage of the improved audibility that the signal processing is supposed to provide in the first place. Finally, some of this work was done with first-generation technology with a small number of compression channels and without digital noise reduction or directional microphones. We know that working memory is more of an issue under adverse listening conditions, so hearing aid features that make listening easier might reduce the role of working memory. 

19. If working memory is more of an issue under adverse listening conditions, should assistive technology also be considered?

Sure. Because we know that low working memory is associated with difficulty understanding speech in noise (Akeroyd, 2008), this is also a good time to plan for technology that will improve signal-to-noise ratio. In that category we would suggest good directional microphone technology and that you consider recommending remote microphones, which can dramatically improve SNR (Wolfe et al., 2015). 

20. That is a lot of information, and I’ll have to think about how best to incorporate it into my practice. What can I expect to happen next in this area?

There are a number of researchers in both the audiology and psychology domains who are working to better define the consequences of reduced cognition and how it should direct clinical choices. In general medical research, the U.S. Preventative Services Task Force has called for studies of the consequences of broader cognitive screening, such as over-referral or increased stress on patients and families (Moyer, 2014). Watch for more convenient and time-efficient cognitive tests and also for more research to confirm whether patients with particular cognitive profiles should be fit with different hearing aid processing. It's an exciting time for audiologists as we improve our focus on the whole patient - two ears plus brain - and gain the diagnostic tools to do it.

Acknowledgments

The author thanks Jing Shen, Angela Roberts, Fernanda Heitor, Thomas Lunner and Elaine Ng for many helpful conversations about cognition and communication. Work that contributed to this article was supported by the National Institutes of Health (R01 DC006014 and R01 DC012289). 

References

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