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Undiagnosed Pre-Existing Hearing Loss in Alzheimers Disease Patients?

Hearing impairment is an invisible handicap, yet its effects upon ones personal health, happiness, and personal well-being are very real.

Vignette:

The adult children of 87 year-old Anna Smith were concerned about her mental health. She lived alone. Although no major mishaps occurred, they were concerned she was becoming reclusive and depressed. At family gatherings she kept to the side and didnt participate in conversations. Family members attempted to include her, but her responses were inappropriate and off-subject. Family members were embarrassed to keep trying. Her family physician placed her on anti-depressant medication. The medication caused her to be anxious and she stayed awake all hours. Anti-anxiety medication was added. She was soon referred to a local psychiatrist. The psychiatrist administered the Mini Mental State Examination (MMSE) battery, on which she scored 10 errors, indicating moderate Alzheimers disease (AD). Her children were distraught over the diagnoses, but concluded based on their observations and the doctors, that Alzheimers was apparent. Plans were made to take Power of Attorney for her real and personal assets and she was admitted to a nearby nursing home.


Introduction:

An ongoing and pervasive lack of public and professional awareness regarding the importance of ruling out hearing loss and auditory disorders prior to diagnosing Alzheimers disease is apparent.

For example, in The Caregiver Handbook (Area Agency on Aging, 2004), an otherwise excellent publication regarding management advice and related information for those suffering with dementia, there is no mention of audiology, audiologists, hearing aids, hearing specialists, hearing impairment or the cognitive effects of undiagnosed and uncorrected hearing loss. The section titled Communicating with someone who has dementia reads just like instructions for communicating with someone with severe hearing impairment.

Likewise, graduate-level textbooks dealing with memory, cognition, geriatrics and eldercare fail to relate the link between cognitive function in older adults and auditory disorders (Schultz & Salthouse, 1999; Matlin, 2002). From public to professional, from diagnosis to treatment, and from government regulatory agencies to research institutions, the likely and reasonable examination and exploration of hearing loss, as an undiagnosed, pre-existing condition in patients suspected of having Alzheimers disease, appears non-existent.

Alzheimers Disease: At Best, a Difficult-to-Diagnose Condition

Alzheimers disease is a degenerative form of mental illness. Symptoms of Alzheimers disease (AD) can be caused by many independent and over-lapping factors. Alzheimers-like symptoms can be attributed to disease-causing genetic mutations, subdural hematoma, chronic hypothermia, vitamin B-12 deficiency, adverse drug interactions, mercury or manganese poison, Huntingtons disease, alcoholism, and Mad Cow disease (Rait et al, 2005; Adviware, 2005; Blackwell et al, 2004; Lawrence et al, 2003) and hearing impairment.

AD is enormously difficult to diagnose for even the best trained professionals. In 1996, researchers at Columbia-Presbyterian Hospital, in a post-mortem investigation of patients previously diagnosed with AD, found a 45% misdiagnosis rate (Alzheimers Foundation, 2005). In addition, normal age-related cognitive changes have been implicated in cases of misdiagnosis and overdiagnosis of AD, signaling the need for better, more accessible, cost-effective diagnostic methodologies (National Institute on Aging, 2002).

But, just as an auditory evaluation was lacking in the vignette above, it is absent in most cases of AD (Chartrand, 2001b; Ullman et al, 1989; Peters, Potter, and Scholar, 1988). Other cognitive conditions, such as depression, anxiety and anti-social behaviors caused by previously undiagnosed and uncorrected hearing loss have been documented in the literature (Chartrand, 2001a).

In the above vignette, which represents a typical scenario, hearing status was not considered, or was disregarded by family and health professionals, each of whom made decisions critical to the well-being of Mrs. Anna Smith.

The most commonly used screening examinations, the Mini Mental State Examination (MMSE), the Sternberg Memory Scan and California Verbal Learning Test, are all administered verbally (i.e. using spoken words) to older adults (Dumont and Hagberg, 1994). These tests assume normal hearing acuity and normal central auditory processing abilitytwo separate and distinct areas of concernin a demographic age-group fraught with auditory disorders.

The thesis of this paper is that any/all thorough and comprehensive clinical assessments regarding cognitive function in older adults must begin with a thorough and comprehensive audiometric evaluation, by a licensed audiologist. Furthermore, if an auditory deficit is found, aural rehabilitation should be facilitated before a true and valid assessment of cognitive function can be rendered (see Figure 1).

Figure 1. Symptom analysis and comparison between moderate Alzheimers disease and untreated hearing loss.

chartrand_alz_fig1.gif

Figure 2 (below) demonstrates the prevalence of hearing impairment in the different age-groups. Hearing impairment becomes quite concentrated in the older population. For example, 36% of the population between 65 and 84 years of age have hearing loss, whereas 66% or more of those age 85 years and above have hearing loss (Aural Rehab Concepts, 2000). The aging of America continues unabated, with those 85 years and older making up the fastest growing demographic age group (U.S. Census Bureau, 2005).

Figure 2. Prevalence of hearing impairment across age-group populations.

chartrand_alz_fig2.gif

The prevalence of hearing loss and AD in the general population track similarly in age-group distribution (see Figure 3 below).

Figure 3. Prevalence of AD in the various age-groups.

chartrand_alz_fig3.gif

Co-Morbidity Probability:

As is evidenced above (see figures 2 and 3) as aging occurs, the probability and incidence of AD and hearing loss increase. Importantly, these are not mutually exclusive factors. The probability that the two conditions are co-morbid contributors to an individuals possible disability increase with age.

Mental health professionals should ascertain the auditory status of the older adult before deriving a diagnosis or proceeding with treatment of/for cognitive/memory disorders.

Possible Referral Path:

To accomplish a thorough and comprehensive audiometric evaluation on suspected Alzheimers disease patients, the following steps may serve as a template:

  1. Possible AD suspicion by family member.
  2. Family member urges primary care physician (PCP) evaluation.
  3. PCP evaluates overall health and refers to audiologist for comprehensive
    audiometric evaluation (acuity tests and auditory processing analysis).
  4. Audiologist reports findings to PCP and initiates amplification and aural rehabilitation for appropriate patients (hearing aids, assistive listening devices, alerting devices, classroom or group AR sessions with family members and significant others).
  5. Patient is re-evaluated by PCP after appropriate audiologic management and after adaptation period (60 to 90 days).

Figure 4. Though AD patients come through varying referral doors the ultimate pathways for assessment and treatment should vary little.

chartrand_alz_fig4.gif

Summary:

Each situation and each patient is unique and no one model serves to address all possible presentations, management options and outcomes.

However, the point has been made that many potential AD patients, particularly the most aged, are highly likely to have demonstrable hearing loss requiring diagnostic audiology tests and audiologic intervention. Attending to audiologic issues prior to diagnosing AD, makes intuitive sense and potentially leads to far better outcomes for all concerned.

chartrand-pic.gifAbout the author
Max Stanley Chartrand serves as managing director for DigiCare Hearing Research & Rehabilitation. He is profoundly deaf and utilizes a cochlear implant. As a widely published author and educator in the hearing field he brings unique insights into the assessment and treatment of the hearing impaired. Contact: (719)676-3277 or by email at www.digicare.org


Selected Audiology Online HYPERLINKS to information on Alzheimers Disease:

http://www.audiologyonline.com/interview/displayarchives.asp?interview_id=293

www.audiologyonline.com/articles/arc_disp.asp?id=400

www.audiologyonline.com/news/displaynews.asp?id=1233

www.audiologyonline.com/news/displaynews.asp?id=778

www.audiologyonline.com/articles/arc_disp.asp?id=352

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Alzheimers Foundation, (2005). Cognitive Impairment Common in Older People and a Risk Factor for Dementia. Retrieved on May 29, 2005, from www.alzfoundation.com/news2.htm

Area Agency on Aging, (2004). Caregiver Handbook: For caregivers of older adults in Fremont, Chaffee, Custer, and Lake Counties. Upper Arkansas Area Council of Governments, provided by Aging Services Division of the Denver Regional Council of Governments.

Aural Rehab Concepts, (2000). Prevalence of hearing loss by age-group in the United States. Retrieved on May 27, 2005, from www.digicare.org

Blackwell, A.D., Sahakian, B.J., Vesey, R., Semple, J.M., Robbins, T.W., and Hodges, J.R., (2004). Detecting Dementia: Novel Neuropsychological Markers of Preclinical Alzheimers Disease. Dementia and Geriatric Cognitive Disorders, 17: 42-48.

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Chartrand, M.S., (2001B, November). Hearing Health Care and Alzheimers Disease: The role of hearing healthcare in treating patients with Alzheimers disease. The Hearing Review, pp.26-29.

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