Reversible dementias.

With so many conditions that can manifest in dementia, the question arises as to how extensive an evaluation need be done on the individual patient presenting with dementia. Thorough physical, neurologic, and psychiatric examinations are the cornerstones of the work-up, with special attention paid to the history, use of medications, and mental status of the patient. Laboratory tests recommended by the National Institutes of Health Consensus Conference on Differential Diagnosis of Dementing Diseases include a complete blood count, electrolyte and metabolic screen, thyroid panel, vitamin B12 and folate levels, syphilis serology, urinalysis, chest radiograph and electrocardiogram, and head CT scan. These evaluations are sufficient to diagnose the majority of treatable dementias. Other evaluations including magnetic resonance imaging, electroencephalography, cerebrospinal fluid examination, cerebral blood flow and metabolism measures (rate of cerebral blood flow, single photon emission computed tomography, and positron-emission tomography), and brain biopsy all can be of additional assistance in diagnosing the cause of the dementia when justified by the clinical setting. When the appropriate diagnosis is made, therapy is directed at the primary disorder. Successful treatment of the primary condition may result in stabilization or partial or complete reversal of the cognitive disturbance. In some instances, judicious pharmacologic management of the accompanying behavioral disturbance may be required.