Second edition

05.qxd 3/10/08 9:34 AM Page 183
side-effects occur, or one reaches a maximum dose (approximately
5 mg of risperidone or 20 mg or haloperidol). The
patient should then be started on a regular daily dose,
roughly equivalent to the total amount required in p.r.n.
doses, with an order for repeat doses on as needed basis; on
subsequent days, the total daily dose should be adjusted
based on the clinical situation and on the amount required in
p.r.n. doses over the preceding 24 hours. In non-emergent
situations, one may begin with risperidone in a dose of
0.5–1 mg or haloperidol in doses of from 2 to 5 mg, with
subsequent dosage adjustments made on a daily basis. Other
antipsychotics, for example, quetiapine, although not as yet
proven effective in blinded studies, are, in fact, used with
success, and may be considered. Quetiapine may be given in
emergent situations in doses of 25 mg orally every 2–3 hours
until one of the end-points just described, with the maximum
total dose being roughly 200 mg; in non-emergent situations
one may begin with quetiapine in a dose of from
25 to 75 mg, with subsequent daily adjustments. Lorazepam
is often used in general hospital practice; however, as pointed
out in Section 6.4, blinded work suggests that the side-effects
of lorazepam may outweigh any benefits.
In some cases, restraints may be required: one should
not be shy about ordering these, as they may be life-saving.
5.4 AMNESIA
Memory is technically divided into two broad types: memory
for how things are done (known as procedural memory)
and memory for things that have happened in the past
(known as declarative memory). An example of procedural
memory would be one’s ability to remember how to ride a
bicycle or play a piano, and examples of declarative memory
include one’s ability to remember what happened
5 minutes earlier, a day earlier, or years ago. These two types
of memory are quite distinct, and procedural memory may
remain intact in cases of profound deficits in declarative
memory (Cavaco et al. 2004). From a clinical point of view,
disorders of declarative memory are most important, and
this section focuses on these.
Defective memory may or may not be accompanied by
other cognitive deficits, such as confusion or deficits in
abstracting or calculating abilities; when other deficits are
present, consideration, as discussed below under
‘Differential diagnosis’, should be given to a diagnosis of
syndromes such as delirium or dementia. This section
focuses on amnesia as a specific syndrome, characterized
by a more or less isolated and ‘pure’ memory deficit.
Clinical features
New memories are formed on an ongoing basis and this
process may occur either automatically or as a matter of
effort, for example when one ‘pays attention’ to something
in an attempt to ‘commit’ it to memory. Once memories
5.4 Amnesia 183
are formed, and, as it were ‘stored’, they may, with a greater
or lesser degree of difficulty, be recalled. Amnesia may
affect either one of these aspects of memory: when there is
difficulty in forming new memories, one speaks of ‘anterograde’
amnesia, and when there is difficulty in summoning
up memories one speaks of ‘retrograde’ amnesia.
Anterograde amnesia is often also referred to as ‘shortterm’
memory loss, and is tested for, formally, by giving
patients three words to remember, having them repeat
them once, and then, after 5 minutes spent on other items,
coming back and asking patients to recall the three words,
noting how many are accurately recalled: normally, all
three are remembered. Informally, one may find during
the interview that patients with short-term memory loss
repeat the same question they asked minutes earlier, as
they have no recall of the answer that had been provided.
Retrograde amnesia is also referred to as ‘long-term’
memory loss, and is tested for during the interview by a
series of questions, focusing on memories of autobiographic
events successively more distant in the past. Thus,
one may ask patients what they had for breakfast, what
brought them to the hospital, how they had spent the past
few weeks, where they lived, went to school, etc.; long-term
memory for public events may similarly be tested by asking
about current newsworthy events or by asking patients to
name the last four presidents.
There are three different types of amnestic syndromes.
The first is constituted by transient episodes characterized
by anterograde amnesia with a variable retrograde component.
The second type is chronic and characterized not
only by an anterograde component but also by a prominent
retrograde one. The third is quite rare, and is characterized
primarily by a deficit in retrograde memory. Each
of these is now considered in turn.
EPISODIC ANTEROGRADE AMNESIA
Episodes of anterograde amnesia typically begin abruptly
and generally resolve in less than a day. During the episode,
patients are unable to keep track of what is happening, and
are unable to recall three out of three words after 5 minutes.
There may also be a retrograde component, in that patients
may have difficulty recalling what happened in the minutes
or hours (and sometimes months or years) just prior to the
onset of the episode. Once the episode terminates, patients
are once again able to keep track of ongoing events, and are
able to recall three out of three words after 5 minutes; furthermore,
they are able to recall events that happened up
until, or just before, the episode began. Notably, however,
they are unable to recall what happened while they were in
the episode: looking back, it is as if there is an ‘island’ of
amnesia, a period of time for which they have no recall.
CHRONIC ANTEROGRADE AMNESIA WITH A
RETROGRADE COMPONENT
Depending on the underlying cause, as discussed further
on, this type of amnesia may have either a relatively acute