Central Nervous System (CNS) Medications and Delirium
Delirium is a condition of acute and reversible confusion characterized by fluctuation, inattention, disorganized thinking, and an altered level of consciousness. The instrument most commonly used to assess delirium in the acute setting is the confusion a
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Delirium is a condition of acute and reversible confusion characterized by fluctuation, inattention, disorganized thinking, and an altered level of consciousness. The instrument most commonly used to assess delirium in the acute setting is the confusion assessment method or CAM. The CAM has been validated against geriatric psychiatrists’ ratings using DSM-III-R (Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised; American Psychiatric Association [APA] 1987) criteria and has been shown to have sensitivity between 94% and 100% and specificity between 90% and 95% (Inouye et al. 1990). It is based on DSM-III (APA 1980) and DSM-IV (APA 1994) criteria for delirium (Table 1) and assesses four features of delirium: 1. Acute and fluctuating, 2. Inattention, 3. Disorganized thinking, and 4. Altered level of consciousness. Delirium is common in older adults, ranging from 13% to 89% depending on the care setting (Fick et al. 2002). Although delirium has many causes (see partial list in Table 2), it is often related to CNS-active medication use, which is reversible, treatable, and preventable. Certain groups are more vulnerable to drug-induced
D.M. Fick (*) School of Nursing, The Pennsylvania State University, University Park, PA 16802, USA e-mail: [email protected]
delirium, most notably older adults and persons with dementia who already have a decreased cognitive reserve (Kolanowski et al. 2010). While the mechanism for drug-induced delirium is not well understood, evidence points to the major roles of anticholinergic failure and GABAergic function (Inouye and Ferrucci 2006). Older adults also are more susceptible to delirium due to age-related changes such as a decrease in total body water and lean body mass, an increase in body fat, and a decrease in glomerular filtration rate and albumin (Cassell et al. 2003). Drug-induced delirium may result from several different agents—these include drugs with anticholinergic properties such as antihistamines (diphenhydramine), tricyclic antidepressants (amitriptyline), narcotics, sedative-hypnotics, and antipsychotics. Benzodiazepines have been found to be associated with delirium in several studies with older adults across all care settings. Another drug category shown to sometimes cause delirium is antibiotics. Several such medications in the Beer’s criteria have been found to trigger delirium (Stockl et al. 2010). Although delirium is often caused by drug toxicity, it also may stem from drug withdrawal if not properly tapered—as in the case of benzodiazepines. Finally, central nervous system (CNS)-active medications, which are widely prescribed to older adults for the management of behavior problems and other chronic conditions, are sometimes inappropriately given. Older adults with
M. Wehling (ed.), Drug Therapy for the Elderly, DOI 10.1007/978-3-7091-0912-0_20, # Springer-Verlag Wien 2013
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Table 1 DSM-IV-TR criteria for delirium A. Disturbance of consciousness (i.e., reduced clarity of awareness of the environment) with reduced abili
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