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Dementia is a common disorder with a prevalence that doubles every 5 years after the age of 60 years, thereby affecting up to 45% of those aged 85 years and older. Dementia is defined as an acquired, persistent, and usually progressive impairment in intellectual function, with compromise in multiple cognitive domains, at least one of which is memory. The deficits must represent a significant decline in function, and must be severe enough to interfere with work or social life for the diagnosis to be formally applied. As the disorder progresses, individuals with dementia often fail to recognize family members, are unable to express themselves clearly and meaningfully, and often undergo dramatic personality changes. Table 30-1 lists some of the more common causes of dementia.
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Despite the high prevalence of dementia, the diagnosis is often missed by clinicians, particularly in the early stages. The primary care practitioner can play an important role in diagnosing and treating dementia. An early diagnosis can offer the opportunity to involve patients in meaningful advance care planning while they are still able to express their preferences clearly. In addition, potentially treatable causes, though rare, are more likely to be partially or fully reversed if diagnosed early. Later in the disease, the practitioner can work with other team members to manage difficult behaviors, ensure that the patient is as comfortable and safe as possible, recognize when referral for specialist care is needed, educate caregivers about the condition, and support caregivers in coping with their situations to the best of their abilities. Furthermore, with several pharmacological treatments available for dementing illnesses, it has become more important for physicians to be proficient in diagnosing specific subtypes of dementia and knowing what therapies may (or may not) be helpful for that syndrome.
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Alzheimer disease (AD) is the most common form of dementia, accounting for about 60–70% of the cases. The age of onset varies considerably, but most commonly symptoms arise after the age of 70 years. Incidence of the disease increases with age. Women may be at a slightly higher risk of developing the disorder than men. The rare patient with early onset of AD (before the age of 60 years) may have a genetic disorder with an autosomal dominant pattern of inheritance, so a thorough family history is important in these cases.
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