Vol 5 n° 1 - Dementia
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4 4 Posters & images in neuroscience Diagnostic decision tree in dementia Diagnostic   criteria   for   dementia   include   memory impairment plus impairment in at least one other cog- nitive function, including aphasia, apraxia, agnosia, or disturbance  in  executive  functioning.4 These  deficits must represent a decline from a previous level of func- tioning and be sufficiently severe to cause significant impairment in social or occupational performance. The diagnosis of dementia begins with a patient presenting with memory difficulties or other complaints. These can include  apathy  or  lack  of  initiative,  disorientation, sleep–wake cycle disturbance, aggression, disinhibition, agitation, depression, anxiety, or psychotic symptoms, as well as impairment in cognitive domains such as atten- tion and concentration, language, motor coordination, recognition of objects, visuospatial skills, insight, and judgment. The patient may be self-referred or brought to the clinician’s attention by concerned family mem- bers, friends, neighbors, or health care professionals. While several decision trees for dementia exist,5,6 the process of differential diagnosis can be summarized in three questions (Table I): • Does the patient have dementia? • Does the patient have dementia alone or dementia comorbid with some other condition(s)? • What is the etiology of the patient’s dementia? A comprehensive work-up for dementia includes a thor- ough history, with reports from informants as well as the patient, a mental status evaluation, and physical, neuro- logical, and neuropsychological examinations.7 Neuro- imaging and specific laboratory tests are recommended, depending upon findings from the history and physical examination. Does the patient have dementia? The first question requires the diagnostician to distin- guish dementia from depression, delirium, intoxication, and other conditions such as mental retardation, schizo- phrenia, bipolar disorder, and malingering. Important issues for the clinician to consider at this stage include whether  objective  findings  of  impairment  support  a diagnosis  of  dementia,  because  memory  complaints unaccompanied by objective impairment may indicate depression.8 Additionally, a cognitive profile suggestive of depression may include decreased working memory, psychomotor slowing, and responses that suggest lack of motivation or effort, as well as prominent mood symp- toms or somatic complaints.9 Clear consciousness and a stable course would tend to rule out delirium, a poten- tially fatal condition that is often reversible when the cause  (eg, medication  or  substance, nutritional  defi- ciency, infection) is remedied. Substance use history, including use of alcohol and prescription medications, could suggest intoxication.An impairment of recent ori- gin with a history of good premorbid functioning would likely  rule  out  mental  retardation  and  serious  psy- chopathology, although new onset of psychotic disorders in middle to late life is more common than previously thought.10 Finally, the presence of secondary gain and inconsistent performance on neuropsychological testing (eg, poorer performance on easier items than on more difficult items) might suggest malingering. Approximately 4 million Americans over the age of 65 have a dementing illness severe enough to interfere with daily functioning.1 As the US population ages, the number of demented individuals is expected to expand dramatically. Thus, accurate differential diagnosis of dementia is increas- ingly important. Moreover, the advent of medications that slow cognitive decline has added impetus to the need for early detection and intervention.2,3