Alzheimer’s Disease: Guidelines for Clinical Practice

The need for modifying procedures to accommodate patients with AD

As an industry and as hearing care professionals we usually talk of patients in terms of normal cognitive and intellectual functioning. Although the typical caseload in a dispensing office indicates the majority of our patients to be in full possession of their mental faculties, many, in fact, are not. As society in the United States continues to age, dementias of all forms are increasing. Most notably, the number of people with Alzheimer’s disease (AD) is estimated at nearly 18 million—up from 5 million just a decade ago. Of the age-related dementias that occur, Alzheimer’s disease is by far the most common, and constitutes 50% of known dementias.¹

Alzheimer’s disease is a progressive neurodegenerative disorder characterized by deterioration in both memory and thinking. Although memory loss is a major feature of the clinical presentation, AD often involves a global cognitive decline, with cognitive deficits in language (aphasia), motor skills (apraxia), and perception (agnosia). Disorientation, difficulty with spatial relations, personality changes, and delusional thinking are also common.² Despite the heterogeneity of the clinical and pathological presentation, AD may be tentatively diagnosed if the following criteria are met:

1. There must be gradual and progressive worsening in short-term memory and at least one other major decline in brain function, such as perception, language, reasoning, or motor skills;
2. These deficits must cause significant impairment in social and occupational functioning and represent a decline in previous levels; and
3. Other medical conditions (major depression, pernicious anemia, hypothyroidism, brain tumors, etc) must be ruled out.²

The progression of symptoms occurs slowly and gradually, and involves a decline in thinking and reasoning, followed by motor disturbances, impaired executive function, and alteration of personality.

A variety of factors are known to underlie the occurrence of Alzheimer’s disease. Age, as a risk factor, is clearly most important. As many studies have confirmed, there is an increased chance of getting Alzheimer’s disease as we get older. Researchers at Harvard Medical School have found that the risk of getting AD doubles every 5 years after age 65, and affects nearly half of those 85 and older.³

Family history has also been implicated. It is well established that those who have a first-degree blood relative with AD are far more likely to get the disease. Based on current research, family history of AD increases disease risk 1.5 to 2 times compared to individuals with no family history.

Epidemiologic studies have confirmed that gender plays a role, with a higher percentage of AD identified among females, even when these results are corrected for the increased portion of women in the older at-risk population. The higher prevalence rate of AD in women has not been explained, but may be due to environmental influences, hormonal effects, and the presence of one or more predisposing genes on the X chromosome.²

A major area of study also involves the relation between AD and one’s level of education and occupation. There is convincing evidence that people with low educational and occupational achievement are at greater risk for AD than the general population.

Other possible related factors for AD include head injury, cardiovascular disease, stroke, Parkinson’s disease, Down’s syndrome, and a history of depressive illness prior to onset of AD.³

Pathogenesis

Alzheimer’s disease is understood to unleash a cascade of events resulting in neuronal loss and shrinkage, neuritic plaques, and neurofibrillary tangles. In early-stage AD, nerve cells shrink in size and synaptic connections, which allow proper communication between cells, disappear. Another defining characteristic of the AD brain is the neurofibrillary tangle. Inside the neurons are proteins that give the neurons structure by binding to microtubules in the cell membrane. In a person with AD, these microtubules disintegrate, and cell structure collapses. These protein fragments then bind with themselves causing neurofibrillary tangles, which ultimately results in nerve cell death.⁴

Disease Progression

In mild AD, memory loss is present in virtually every patient. This is because the disease is believed to strike first in the hippocampus, where short-term memories are stored and converted into long-term memories. Research studies suggest that Alzheimer’s patients may exhibit up to 68% fewer neurons in the region of the hippocampus.¹

Patients in early stages of AD typically rationalize or deny their problems. There may also be impairment in following conversation and understanding speech. Routine chores may take longer to perform and patients can become upset or agitated when something unexpected occurs. Motor skills, perceptual abilities, and social functioning are typically not affected or are minimally affected at this point.

In moderate AD, more neurons in greater areas of the brain are affected, which increases the presentation of deficits already noted while extending into other areas. Patients typically deny the true nature of their illness, and may make up stories to fill in the gaps in their memory. Spatial disorientation in familiar areas is common. Patients demonstrate less concern for appearance, manners, and hygiene. Confusion over the identity of familiar objects and people may be present. Difficulties with organized thoughts and logical explanations make tasks like planning increasingly difficult.

In final-stage AD, vital areas of the cognitive apparatus are drastically diminished, while others disappear entirely. The most essential tasks of day-to-day living require assistance, with the patient unable to recognize themselves or others. Memory loss is often complete, with the patient exhibiting total dependency and requiring institutional care. The patient may become psychotic or delusional, experience hallucinations, and demonstrate aggressive behaviors. Speech is incomprehensible, or the patient may become mute. Patients may be too weak to stand alone unassisted, or they may experience frequent falls. Total assistance is required for all activities, such as toileting, bathing, dressing, and eating.⁵

Current Treatments

Although there is no cure, Alzheimer’s medications can temporarily slow the onset of symptoms and improve the quality of life for patients as well as their caregivers.

The FDA has approved five medications to treat AD:

• Donepezil,
• Galantamine,
• Rivastigmine,
• Tacrine, and
• Memantine.

These drugs are designed to delay symptoms of AD, but do not treat the underlying disease.

Hearing Loss and Dementia

We have already seen that aging is a major determinant in the diagnosis of AD. Given the prevalence of hearing loss among this population, it is not surprising that current research has begun to establish a connection between hearing loss and dementia. Given the likelihood that these conditions may coexist, it is important for the clinician to understand the relationship between these two variables. Specifically, older adults with dementia are more likely to have significant hearing loss than those without dementia⁶ (for a review, see the article by Beck and Flexer in the February 2011 HR ⁷).

Furthermore, hearing loss, when not treated, may exacerbate symptoms of dementia and confound an accurate diagnosis. When dementia is combined with hearing loss, the outcome is worse than the additive sum of the two factors.⁷ Beck and colleagues^8,9 recently noted this “negative synergy”—an effect that results in confusion about spoken words, meaning, and intention. They point out that, when signal quality is degraded due to sensorineural hearing loss (SNHL), greater cognitive effort is required by the listener for sentence comprehension to occur. If cognitive function is undermined by dementia, however, the “reserve capacity” required for sentence comprehension is no longer available. Failure of the cognitive apparatus results in a loss of synthetic ability for the patient (ie, an inability to “fill in the blanks” given distorted or degraded signal quality).^7-9

Thus, a unique interdependence between auditory and cognitive function exists. As the magnitude of the hearing loss increases, greater demands are placed on cognition, and vice-versa. When the cognitive apparatus is impaired by dementia or Alzheimer’s disease, however, a synergy between the two conditions is created. To paraphrase Beck et al: Audition matters more as cognition declines; cognition matters more as audition declines; so when both decline, the patient needs as much assistance in both areas as possible. The bottom line: it’s important for dispensing professionals to realize that speech comprehension difficulties for the AD patient are considerably greater than for patients with normal cognitive function.

Rehabilitative management depends on accurate assessment in both domains. Even the instruments designed to evaluate cognitive function can be undermined by preexisting hearing loss. For this reason, it has been suggested that any evaluation of cognition should be preceded by an evaluation of hearing. Since earlier research has already demonstrated that the use of amplification may actually slow the rate of decline in select patients, the need to evaluate this facility under conditions that ensure optimal audibility should be obvious.

Furthermore, dispensing professionals should be aware that, if the necessary rehabilitative support services are in place, patients with dementia can do well with amplification. Recent developments in hearing aid technology—including sophisticated noise reduction algorithms and wireless communication—may be particularly suitable for this population.

It is unfortunate that, for a variety of reasons, most dementia patients do not receive treatment for their hearing losses. This undoubtably relates to a host of factors (difficulty with testing, perceived need and benefit, etc) that are beyond the scope of this discussion. Hearing care professionals should be aware of the complex nature of these interactions and be prepared to advocate effectively for the rehabilitative needs of their patients. Inasmuch as the symptoms of hearing loss, dementia, and affective disorders may overlap, it is important for us to inform health care providers of the need for audiological evaluation and rehabilitative services.

Similarly, dispensing professionals should be prepared to evaluate the mental status of their patients by asking informal questions to assess a patient’s memory and orientation, or perhaps to administer a screening instrument such as the Mini Mental State Exam,¹⁰ or the Short Portable Mental Status Questionnaire.¹¹

Suggestions for Enhancing Communication

Research studies indicate that AD patients undergo a progressive deterioration in linguistic competence, which results in overall inability to speak their minds and to express their feelings effectively. The following guidelines may be used by the professional to facilitate communication with these patients.

1. Get the patient’s attention before speaking to them. Touch them on the arm or shoulder to focus their eyes on you. If the person does not care to be touched, speak in a louder voice than usual. Speak only when visible to the person.
2. Establish eye contact and maintain it throughout the conversation. Situate yourself on the same positional level as the patient. Always face the listener when you are speaking so that visual cues can be utilized.
3. Speak slowly and allow patients plenty of time to respond. It may sometimes be necessary to repeat a sentence more than once. Take twice as long to form your words as you usually do.
4. Because AD patients are easily distracted and confused, the quieter and simpler the environment, the better. Patients do best in one-on-one conversational situations, and many AD patients cannot converse with several people in the room.
5. Speak simply and stay on one topic at a time. Do not assume that patients can follow rapid conversational transitions. If the listener has a problem with a particular word or phrase, find a different way of saying it rather than repeating the original word over and over again.
6. When initiating a conversation, begin by introducing the topic to be discussed. Move in an unhurried manner and use body language that conveys understanding and empathy.
7. Learn the limits of a person’s attention span and do not exceed it. Short, quiet rest periods between speaking efforts will be welcomed by the patient. Phrase sentences in the present tense, as these are more easily understood by the patient.¹²

Future Directions

There are a variety of treatment options in various stages of development and approval for Alzheimer’s patients. For additional information, visit the Alzheimer’s Association at www.alz.org.

Acknowledgement

The author thanks Barbara LaCoppola for her assistance with preparation of this manuscript.

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Correspondence can be addressed to HR or Carl Chiasson, AuD, at .

Referneces

1. Hearing Loss Association of America. Support HLAA’s Campaign to Make Hearing Aids Affordable. Available at: www.hearingloss.org/SpringAppeal_2011.asp. Accessed June 10, 2011.
2. Donahue A, Dubno JR, Beck L. Accessible and affordable hearing health care for adults with mild to moderate hearing loss. Ear Hear. 2010;31(1):2-6.
3. Kochkin S. MarkeTrak VII: Obstacles to adult non-user acquisition of hearing aids. Hear Jour. 2007;62(4):24-50.
4. Amlani AM. Will federal subsidies increase the US hearing aid market penetration rate? Audiology Today. 2010;22(3):40-46.
5. Callaway SL, Punch JL. An electroacoustic analysis of over-the-counter hearing aids. Am J Audiol. 2008;17(1):14-24.
6. Ramachandran V, Stach BA, Becker E. Reducing hearing aid cost does not influence device acquisition for milder hearing loss, but eliminating it does. Hear Jour. 2011;64(5):10-18.
7. Beck DL, Flexer C. Listening is where hearing meets brain…in children and adults. Hearing Review. 2011;18(2):30-35. Accessed November 28, 2011.
8. Beck DL, Clark JC. Audition matters more as cognition declines; cognition matters more as audition declines. Audiology Today. March/April 2009:48-59.
9. Schum D, Beck D. Negative synergy: hearing loss and aging. Available at: www.audiologyonline.com/articles/article_detail.asp?article_id=2045. Accessed November 28, 2011.
10. Instructions to the Administration of the Mini-Mental State Exam. Available at: geriatrics.uthscsa.edu/tools/MMSE%20(english-spanish).pdf. Accessed December 2, 2011.
11. The Short Portable Mental Status Questionnaire (SPMSQ). Available at: www.npcrc.org/usr_doc/adhoc/psychosocial/SPMSQ.pdf. Accessed December 2, 2011.
12. Carroll DL. When Your Loved One Has Alzheimer’s. New York City: Harper and Row; 1989.