Undiagnosed Pre-Existing Hearing Loss in Alzheimer's Disease Patients?

"Hearing impairment is an invisible handicap, yet its effects upon one's 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 didn't' 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 Alzheimer's disease (AD). Her children were distraught over the diagnoses, but concluded based on their observations and the doctors,' that Alzheimer's 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 Alzheimer's 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 patient's suspected of having Alzheimer's disease, appears non-existent.

Alzheimer's Disease: At Best, a Difficult-to-Diagnose Condition

Alzheimer's disease is a degenerative form of mental illness. Symptoms of Alzheimer's disease (AD) can be caused by many independent and over-lapping factors. Alzheimer's-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, Huntington's 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 (Alzheimer's 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).