A Guide to the Diagnosis and Assessment of Alzheimer's Disease

Section 3
Alzheimer's disease in primary care ­ the diagnostic process

• Provide a framework to facilitate the diagnosis and management of AD in the primary care setting

The primary care physician (PCP) currently cares for the majority of patients with AD, either at home or in nursing homes. The PCP is in an excellent position to recognize and manage AD within the community (Table 17). The challenge is to establish the diagnosis early in the illness. Standard assessment techniques available give a high level of diagnostic accuracy (85%).

The early diagnosis of AD may:

• Allow early intervention with supportive measures and/or symptomatic treatment
• Lessen the burden for caregivers
• Allow appropriate specialist referral
• Improve the quality of life for both the patient and the caregiver

The diagnosis of AD requires a structured and systematic approach (Figure 8). The process requires proactive case-finding for cognitive impairment. Any changes in cognition or functioning that raise concern for the patient, family or physician working directly with the patient should trigger a preliminary assessment for the possibility of dementia.

Assessment tools

If dementia is suspected, a short assessment battery can be employed to screen for AD (Table 18). This has been discussed in detail in the previous section. These tools can be used easily in the primary care setting, take a relatively short time to conduct and can be carried out by non-physician staff. A picture can be built up of the cognitive and functional status of the patient, both past and present. Using the diagnostic criteria for AD (see Section 1), it is generally possible to make a diagnosis by straightforward clinical assessment methods, including neuroimaging and laboratory tests.

• Define all contributory factors and other illnesses
• Discuss the diagnosis, and differentiate other types of dementia
• Withdraw non-essential drugs that may interfere with cognition
• Treat or manage concomitant illnesses (e.g. depression, hearing loss)
• Discuss the value of symptomatic therapies
• Monitor functional ability (e.g. driving, safety)
• Referral to specialist if appropriate
• Advise on will-making and advance directives
• Refer to local AD association for support

• Help caregivers discover and optimize the patient's preserved function
• Monitor and treat complications
• Facilitate caregiver support (respite and day care programs)
• Be aware of caregiver burden and stress
• Plan institutionalization, if needed
• Assist with end-of-life decisions

• Case-finding
• Clinical history
  - Detailed interview with patient and a reliable informant
• Physical examination
• Laboratory tests
• Functional assessment
  ­ FAQ
• Cognitive status
  ­ MMSE
  ­ CDT
• Neuroimaging
  ­ CT scan without contrast

Clinical history

The first step in the clinical assessment of AD is to take a thorough clinical history. Interviewing both the patient and a reliable informant will help to establish the pattern of deterioration. In addition, it will determine past levels of intellect, functioning and social interaction.  

Physical examination

A complete physical examination and specific laboratory tests will uncover factors that may be contributing to or causing cognitive or functional impairments: thyroid dysfunction, vitamin B₁₂ deficiency and syphilis. Concomitant illnesses and problems must be identified and treated as necessary.

Functional status

A significant decline in functional ability is a characteristic of AD and forms part of the diagnostic criteria. Assessing functional status will:

The informant-based Functional Activity Questionnaire (FAQ) is a rapid way of assessing functional status in primary care.

• Establish the extent of functional disability in IADLs/ADLs
• Determine the amount of assistance that is required
• Enable the planning of future care

Cognitive dysfunction is the hallmark of dementia and must be objectively assessed. It is therefore essential to assess cognitive decline. Combining the Mini Mental Status Examination (MMSE) and the Clock Draw Test (CDT) will establish an objective view of the cognitive functioning of the patient.

Neuroimaging

Neuroimaging is a adjunct in the diagnosis of AD. Brain imaging helps eliminate the possibility of other causes of the dementing illness, such as tumors and infarcts, and can show evidence of cerebrovascular disease. Occasionaly, neuroimaging will be supportive of a diagnosis of AD.

CT scan without contrast may be considered. It provides an inexpensive and widely available opportunity to appraise the medial temporal lobe and assess alterations occurring in other areas of the brain.

This algorithm provides a broad and structured approach to the diagnosis of AD, that can be adapted to meet national and local requirements.

The management of AD

This stepwise approach (Figure 8 Above) will generally allow the clinical diagnosis of AD to be made and to eliminate the possibility of other dementias. If the diagnosis is inconclusive, it may be necessary to refer the patient to a specialist for further evaluation (Table 19 Below).

• Inconclusive diagnosis
• A typical presentation, progression or examination
• Second opinion requested by family or patient
• Behavioral/psychiatric symptoms (e.g. depression) not responding to treatment
• Need for specialized patient care
• Situations where there is family dispute regarding the diagnosis or ongoing management

Initial assessment and full investigation as described above usually requires more than one visit, but once the diagnosis is certain, scheduled follow-up, beginning at short intervals to answer initial questions, will be required. Continuing, scheduled follow-up visits will be needed, in order to implement the proactive, anticipatory approach that will reduce the impact of the illness on the patient and family.

At each follow-up visit, ask about the patient's:

• Cognitive function: patterns of change since their last visit, especially any episodes of acute change
• Functional ability: in particular, alterations in daily living skills essential for independence, such as driving, shopping, traveling
• Behavior: ask about mood and motivation and any difficulties the family has with handling the patient
• General health: always include questions on nutrition, weight, sleep, mobility/gait, balance problems/falls and any bladder (incontinence) or bowel (constipation) problems
• Routine health maintenance: ensure the patient is undergoing routine medical checks (e.g. immunization, cancer checks, etc)

• How they are coping with looking after the patient
• What their level of health is and what efforts they are taking to remain in good shape for the future

AD affects not only the patient but also the caregiver. Caregivers face a tremendous burden, which increases as the disease progresses. Caregivers tend to cope better when they know what to expect. To ensure this, access to information is required either through published materials and/or support organizations such as the Alzheimer's Association. This enables family members to become well-informed and capable of managing the stresses that are inevitable. In the mid stages of the disease, day care programs and respite care can help reduce the caregiver burden and may delay institutionalization.