Second edition

05.qxd 3/10/08 9:34 AM Page 174
174 Syndromes of cognitive impairment
more of the common causes of dementia, most notably
Alzheimer’s disease. Given this, it may be just as accurate
to refer to these patients as being in the prodromal stage of
a dementia.
Clinical features
Cognitive impairments seen in MCI include deficits in
short-term memory, calculating ability, abstracting ability,
visuospatial ability, etc. Of all these deficits, short-term
memory loss is the most common and, when this is seen in
isolation, one speaks of the ‘amnestic’ type of MCI. When
two or more deficits are present (which may or may not
include difficulty with short-term memory), the term
‘mixed domain’ MCI is used; when memory is intact but
some other deficit is present, one speaks of ‘single-domain
non-memory’ MCI.
Cognitive impairment typically occurs gradually, and
should be present for roughly a year before the diagnosis is
made. In all three types, although patients or others report
the cognitive impairment, which in turn is demonstrable
on clinical evaluation, there is nevertheless no significant
disruption to the patients’ routine daily functioning.
Although most cases of MCI demonstrate a gradual
progression over the years, in a minority the impairment
remains stable or undergoes improvement.
Etiology
In autopsy studies (Bennett et al. 2005; Guillozet et al. 2003;
Jicha et al. 2006; Petersen et al. 2006; Storandt et al. 2006), the
most common findings are changes typical of Alzheimer’s
disease in medial temporal structures; other pathologies
found include infarcts and diffuse Lewy body disease.
There is also an association with pre-existing depression
(Barnes et al. 2006; Geda et al. 2006) and with chronic use
of medications with anticholinergic properties (Ancelin
et al. 2006).
Differential diagnosis
MCI must be distinguished from dementia and amnesia.
One differential feature that distinguishes MCI from both
of these is the severity of the cognitive deficits and their
effect on activities of daily living. As noted earlier, in MCI
the deficits are mild and tend to have little or no effect on
day to day functioning; in contrast, in dementia and amnesia
the deficits are of sufficient severity to cause obvious
difficulties in patients’ abilities to function. Importantly, in
many, if not most, cases, long-term follow-up reveals a
progression of both the severity and number of cognitive
deficits to the point when a diagnosis of dementia is justified
(Tschanz et al. 2006).
Delirium is immediately distinguished from MCI by the
presence of confusion, which, by definition, is absent in MCI.
Treatment
The overall treatment of patients with MCI should begin
with a thorough diagnostic evaluation, as discussed in the
chapters on dementia and amnesia, with every attempt
being made to determine the underlying cause; treatment
should then proceed as for that cause. In cases of amnestic
MCI, most of which represent ‘incipient’ Alzheimer’s disease,
donepezil may be given (Petersen et al. 2005); in cases
preceded by depression wherein depressive symptoms persist,
a case may be made for treatment with an antidepressant;
and when toxic factors are present, for example
anticholinergic medications, these, obviously, should be
discontinued.
5.3 DELIRIUM
Delirium is one of the most common neuropsychiatric disorders
seen in general hospital practice and is especially
common among the hospitalized elderly (Francis 1992).
Prompt diagnosis is critical as, in many cases, the underlying
cause of the syndrome, untreated, carries a grave prognosis
(Cameron et al. 1987; Pompeii et al. 1994; Rabins and
Folstein 1982).
Clinical features
Delirium, as reviewed by Lipowski (1983, 1987, 1989), is
characterized by confusion, disorientation, memory loss,
and often other symptoms such as hallucinations and delusions.
The syndrome is typically of acute or subacute onset,
and most patients develop the full syndrome within a day
or two (Levkoff et al. 1992).
Confusion, or, as it is also known, ‘clouding of the sensorium’,
is the cardinal symptom of delirium and is present
in all cases. Patients may appear dazed, their attention
wanders, and they often seem to drift off. In most cases, a
varying degree of incoherence will also be seen (Johnson
et al. 1992; Sirois 1988). Disorientation, found in almost all
cases (Morse and Litin 1971) may be for both place and
time together, or merely in one of these spheres. Memory
loss is typically of the short-term or anterograde type:
patients are unable to remember all of three words after
5 minutes and consequently have grave difficulty in keeping
track of what happens around them. Retrograde amnesia
may also be present but is generally less prominent:
patients may have trouble recalling clearly what happened
in the days or weeks prior to the onset of the delirium.
Hallucinations are seen in about one-half of all cases
(Morse and Litin 1971) and may be either visual or, less
commonly, auditory (Cutting 1987; Sirois 1988). Patients
may see family members in the hospital room, and bugs or
small animals may hide in the sheets. Auditory hallucinations
range from such simple phenomena as bells or sirens
to hearing voices.