from full text JK:
1.1.3 Clinical Significance The prevalence
of delirium in older people
on admission to hospital ranges from 10 to 24%, and delirium develops in a
further 5 to 32% of older patients after admission.[9-11] Advanced age,
dementia and severe illness are important predisposing factors for
delirium. Delirium is associated with a high mortality rate, prolonged
duration of hospital stay and a high rate of discharge to institutional
care.[9,10] Many patients subsequently develop dementia, although it is unclear
whether delirium itself contributes to chronic cognitive impairment or is just
a marker of a subclinical dementing process.. . .
confusion is among a number of potentially treatable causes of dementia.
I. Drugs associated with delirium in prospective medical studies Study Drug No.
and Lavan Tricyclic antidepressants 6 Levodopa 2 Oxybutynin 2 Benzatropine 1
Pethidine 1 Phenytoin 1 Digoxin 1
et al. Narcotics 9 Benzodiazepines
7 Anticholinergics 7 Methyldopa 3 NSAIDs 3
toxicity accounts for between 2 and 12% of cases of dementia in a number of
studies.[19-21] For example, Larson et al. found drug induced confusion in
35 of 308 patients with suspected dementia. Furthermore, the relative odds of
developing drug-induced confusion increased from 1.0 when 0 to 1 drugs were
used to 9.3 when 4 to 5 drugs were used.
[That is a 9 fold increase].
with delirium, there are a number of difficulties in establishing a causal
relationship between dementia and drugs [Yes when a physician sees over 1,000
patients a year, with 15 minute window of which 2.3rd of time spent
is on the computer.]
with anticholinergic compounds is common in nursing home residents, a
population which has a high prevalence of Alzheimer’s disease. For example,
Blazer et al. noted that 60% of almost 6000 nursing home residents (and 23%
of ambulant elderly controls) received drugs with anticholinergic properties,
while up to 32% of nursing home residents and 13% of controls were taking 2 or
more anticholinergic drugs simultaneously
Clinical Features of Anticholinergic Toxicity The CNS effects of
anticholinergic medications include subtle neuropsychological deficits,
especially involving memory and attention, and delirium. Anticholinergic
delirium is characteristically associated with agitated behaviour and florid
visual hallucinations. Signs of peripheral autonomic anticholinergic
toxicity may or may not be present. Anticholinergic medications may also cause
chronic cognitive deficits and mimic Alzheimer’s disease.
drugs used in PD, such as trihexyphenidyl or benzatropine, often cause
cognitive impairment or hallucinations in elderly patients. The high
prevalence of dementia in elderly patients with PD adds to the risk of
anticholinergic induced confusion. De Smet et al. reported that delirium
developed in 93% of patients with dementia and PD compared with 46% of patients
with dementia on drug regimens which did not include anticholinergic agents.
Oxybutynin is used to reduce uninhibited bladder contractions in patients with
increased urinary frequency or urinary incontinence. It has recently been shown
that oxybutynin can cause cognitive deficits in elderly people, and
delirium has also been reported.
et al. studied the antimuscarinic effects of the 25 most commonly
prescribed drugs for elderly patients in the radio-receptor assay. Fourteen
drugs produced detectable anticholinergic effects, and 10 produced levels of
anticholinergic activity, expressed as atropine equivalents, that have been
shown to produce significant cognitive impairment in elderly people.
Cognitive Impairment Due to Psychoactive Drugs Psychoactive drugs are the
commonest causes of drug-induced cognitive impairment.[11,19,41,42] CNS
toxicity with these agents is usually dose-related, although it also depends
greatly on the vulnerability of the individual patient.
Cognitive Impairment Due to Nonpsychoactive Drugs Drug-induced confusion with
the agents discussed in the following sections is often idiosyncratic in
nature, and the diagnosis is easily missed unless clinicians maintain a high
index of suspicion.
II. Drugs associated with cognitive impairment Drug Class Examples Risk Comment
Anticholinergics Atropine Scopolamine High Glycopyrronium bromide is a safer
agent for anaesthetic premedication Benzodiazepines Nitrazepam, Flurazepa,
Diazepam Temazepam High Medium Cognitive impairment is more common with
long-acting agents. Withdrawal delirium also occurs Opioid analgesics Pethidine
(meperidine) High Risk may be highest with pethidine Antipsychotics
Thioridazine Chlorpromazine Risperidone Medium Low Although often used in the
treatment of delirium, antipsychotics with significant anticholinergic activity
can worsen confusion Antiparkinsonian drugs Trihexyphenidyl Benzatropine
Bromocriptine Levodopa Selegiline (deprenyl) High Medium Risk is highest in
drugs with anticholinergic activity Antidepressants Amitriptyline Imipramine
Nortriptyline Desipramine SSRIs High Medium Low Risk is highest in drugs with
anticholinergic activity Anticonvulsants Primidone Phenytoin Medium Low Risk
may be lowest with valproic acid and newer anticonvulsants H2 Antagonistsa
Cimetidine Ranitidine Low Proton pump inhibitors may be less likely to cause
delirium H1 Antagonistsa Chlorphenamine Low Antihistamines are available in
many over-the-counter preparations Cardiovascular drugs Quinidine Digoxin
Methydopa β-Blockers Diuretics ACE inhibitors Medium Low Digoxin toxicity is
dose-related, but in elderly people confusion may occur with normal serum
concentrations Corticosteroids Prednisolone Medium Risk is dose-related NSAIDs
Indomethacin Ibuprofen Medium Low Paracetamol is a safer alternative for short
term use Antibiotics Cephalosporins Penicillin Quinolones Low Although delirium
has been reported with many antibiotics, this may be more related to the effect
of the underlying infection