Whenever the primary care physician suspects cognitive dysfunction, he or she should perform a cognitive mental status examination. Such an examination serves several purposes: it determines whether there is a deficit in cognitive performance, it identifies the aspects of cognition that are impaired, and it quantifies the degree of impairment. The evaluation should also include an assessment of noncognitive phenomena (e.g., mood, illusions, hallucinations, delusions) because a variety of psychiatric disorders can impair cognition and cause distress in the patient or caregiver, or both.
Chapter 1 discusses the Mini-Mental State Examination (MMSE) and suggests ways to determine the presence of abnormal mood, illusions, hallucinations, and delusions. A dementia due to major depression is often accompanied by delusions that are characteristic of depression, such as hypochondriacal beliefs (e.g., no bowel movements for many weeks without evidence of constipation), ideas of poverty (e.g., complaints of no money, insurance, or clothing when that is not the case), or guilt and self-blame (e.g., unfounded beliefs that the person has harmed others). Because depressed patients often feel unwell, with insomnia, anorexia, and lethargy, they may present to their primary care physicians with somatic complaints.
A thorough history and physical examination (including neurologic examination) should be carried out. This is important because most curable causes of dementia are revealed by their characteristic symptoms (e.g., cold intolerance in hypothyroidism) and signs (e.g., hyporeflexia).
A screening laboratory evaluation consists of a complete blood count (CBC), full chemistry panel, thyroid function tests, a serologic test for syphilis, and a B12 level. If the history or physical examination suggests a particular disorder, the physician should request appropriate tests. Thus, exposure to a heavy metal or the finding of a peripheral neuropathy indicates the need for a heavy-metal screen, and exposure to risk factors for HIV necessitates an HIV test.
Indications for head imaging are not well established. Several consensus conferences have concluded that a head-imaging study is not required in all cases of forgetfulness. I recommend that an imaging study be done when the history is of less than three years' duration, the patient is under the age of 70, the neurologic examination identifies a focal abnormality or suggests a specific syndrome (e.g., the gait disorder of hydrocephalus), or the cognitive examination reveals a focal syndrome. In most circumstances a noncontrast head CT is adequate. Many clinicians order a head MRI when they suspect vascular dementia, but the cost is approximately twice that of a CT scan.
A lumbar puncture should be performed after a head-imaging study has been done when the onset of illness is acute or subacute (hours to months), if the history or physical findings are compatible with meningitis or encephalitis, or when the serum fluorescent treponemal antibody (FTA) is positive. An electroencephalogram should be ordered when the level of consciousness is impaired (i.e., when delirium is suspected) or if a seizure disorder or Creutzfeldt-Jakob disease is in the differential diagnosis. The pri mary care physician should request neuropsychological testing when he or she is not sure whether a cognitive deficit is present, when symptoms are atypical, when the patient is young, or when clinical and laboratory findings do not point to a specific syndrome.
If the initial clinical assessment confirms that a cognitive impairment is present, the physician should inform the patient and any accompanying family members that he or she is concerned about the patients memory. The physician should explain the planned laboratory and radiologic evaluations and schedule a follow-up appointment. The majority of patients with Alzheimer disease are unaware that they have a problem and often deny that their impairment is significant (e.g., "I know my memory is not so good, but that's true of everyone my age"). Trying to convince such individuals that they have an impairment when they adamantly deny it is usually unsuccessful. Therefore, I do not recommend confronting the patient with the diagnosis; I merely tell them that there are further tests to order. I sometimes give the family a prescription that states "Dr. Rabins ordered the following tests on February 10th" and suggest that the family show this if the patient resists.
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