Differentiating between age-associated memory impairment and dementia resulting from a medical condition invokes a process of systematic elimination. Doctors often start by looking for conditions that are most readily correctable. If these possibilities can be eliminated, then more serious, irreversible dementias, such as Alzheimer's disease, are considered. In addition, the presence of reversible disorders can complicate the irreversible forms of dementia. In these cases, diagnosing and treating concurrent depression, for example, make it possible to gain a clearer view of any conditions that may persist.
The first step in diagnosis is a thorough medical history and physical examination to identify any vision, hearing, cardiovascular, or other disorders. Although checking for these condtions might seem unnecessary, they often go unrecognized in older adults and can have an important effect on memory.
Tests of mental status--for example, the Mini-Mental State Examination, the Short Test of Mental Status, or the Cognitive Capacity Screening Examination--are also given to check for any basic cognitive impairment. These tests, which take 5 to 15 minutes to complete, offer a baseline for comparison should further testing be necessary.
A history should also include an interview with a family member or close friend. Such an interview can be crucial, because someone close to the patient knows that patient's former level of functioning and therefore is able to help the physician determine whether deterioration has occurred.
The American Academy of Neurology recommends the following tests in the routine evaluation of a patient with dementia:
- complete blood cell count
- serum electrolytes (potassium, sodium, and chloride)
- blood glucose (sugar), blood urea nitrogen, and creatinine
- serum vitamin B12 levels
- depression screening
- a brain scan such as computed tomography (CT) or magnetic resonance imaging (MRI)
