Beyond memory: neuropsychologic features in differential diagnosis of dementia.

Although the term ‘‘dementia’’ is sometimes used as a synonym for memory loss in general or Alzheimer’s disease (AD) in particular, dementia is an umbrella term that describes a constellation of symptoms rather than a specific etiology or disease process. As it is most commonly defined, dementia denotes memory impairment combined with disturbance in at least one other area of cognition (DSM-IV) [1]. This definition best describes patients with medial temporal lobe involvement and may exclude those with pathology in other brain areas. The currently accepted definition of dementia is likely to be revised as understanding of cognitive dementia syndromes and their underlying pathology becomes more sophisticated. Memory difficulty is among the most common cognitive complaints from patients and caregivers alike when describing patients’ cognitive difficulties. Patients are often inexact and attribute difficulties to memory when subsequent cognitive testing reveals that the deficits are in other cognitive domains. Furthermore, although current diagnostic criteria specifically select for memory deficits among those diagnosed with dementia, neuropsychologic testing often reveals significant deficits in other areas of cognition. Using current guidelines (DSM-IV, ICD-9) [1,2], individuals without memory difficulty but with deficits in nonmemory cognition would not be diagnosed with dementia, yet these deficits may have significant impact on everyday functioning and may indicate disease processes. As noted in a previous article in this issue, dementia does not present with just one profile. Although individual differences in presentation exist, individuals with common underlying dementia pathology most often have striking similarities in presentation. Different dementias have different ‘‘signatures’’ that provide important information regarding the etiology and clinical course of the disease. In