Psychiatric Consultation in Long-Term Care: A Guide for Health Care Professionals

4 Delirium

Delirium is a classic geriatric psychiatric syndrome that occurs commonly among elderly people who are frail or have dementia, that is, those who make up most of the residents in a long-term care facility (Inouye 2006; Eeles and Rockwood 2008). When screened, up to 15 percent of the people admitted to a postacute facility are delirious (Kiely et al. 2003). Among LTC residents older than age 85, up to 60 percent may have delirium at some point during their stay (Fann 2000). The prevalence of delirium in an LTC setting may be increasing as a result of the pressure to reduce the length of hospital stays (Lyons 2006). Delirium in elderly people is also called acute confusion , acute confusional state, and cognitive/mental status change. Central features of delirium are an acute onset and a fluctuating course, a disturbance of consciousness (hyperalert or drowsy), and inattention (a reduced ability to focus, sustain, or shift attention). Disturbances of the sleep-wake cycle, of perception, and of thinking (disorganization, incoherence) and a reduced awareness of one’s environment generally accompany delirium. Although the onset of these symptoms is typically described as acute (often within hours or one to two days), a subacute onset of delirium over days to weeks is not uncommon in LTC populations. Psychosis can accompany delirium, irrespective of the latter’s cause. At the cellular level, delirium is considered to be a reversible dysregulation of neuronal membrane function. This involves the selective vulnerability of certain populations of neurons (e.g., the reticular activating system) and neurotransmitter dysfunction (e.g., acetylcholine and gamma-aminobutyric acid). There are four subtypes of delirium: C H A P T E R 4 Delirium D E L I R I U M 107 •฀ Agitated฀(hyperactive)฀delirium฀is฀characterized฀by฀agitation,฀hallucinations , hyperalertness or vigilance, and inappropriate behavior. It accounts for 25–30 percent of the cases of delirium. •฀ Quiet฀(hypoactive)฀delirium฀is฀characterized฀by฀somnolence฀(the฀resident tends to sleep all the time), apathy, sluggishness, lethargy, and withdrawn behavior. It accounts for 50–55 percent of the cases of delirium . Quiet delirium is more likely to be overlooked or to be misdiagnosed as depression, and it may carry a higher risk of mortality than agitated or mixed delirium. Often, quiet delirium goes unrecognized until the resident becomes stuporous (difficult to arouse) or comatose (unarousable). •฀ Delirium฀with฀normal฀psychomotor฀activity฀carries฀the฀lowest฀risk฀of฀ mortality, compared with other types of delirium. •฀ Mixed฀delirium฀is฀characterized฀by฀a฀pattern฀of฀fluctuating฀symptoms,฀ including periods of agitation and times when the resident is quietly confused and withdrawn. Risk Factors and Etiological Factors In LTC populations, dehydration and infection are the two most common causes of delirium. Constipation and drug-induced delirium are also common . Table 4.1 lists risk factors for delirium in LTC populations (Flaherty and Morley 2004). Although all LTC residents have at least one risk factor for delirium , many have several, and these residents are at highest risk of delirium. Table 4.2 lists some of the common causes of delirium in LTC populations (Inouye 2000; Flaherty and Morley 2004). Although typically one or two of the common causes of delirium can be identified as precipitating, delirium is multifactorial in most residents. Thus solving one factor alone is unlikely to resolve the delirium. In high-risk residents, a relatively benign insult, such as the addition of a sleeping pill or sleep aids containing diphenhydramine (e.g., Tylenol PM), may be sufficient to precipitate delirium. Diagnosis and Work-Up Recognizing delirium may be difficult, but its diagnosis can be improved through a cognitive assessment and the use of simple diagnostic tools (Lyons 2006). Chapter 2 contains clinical pearls to detect delirium early and tools to identify delirium. Delirium is often noticed in an agitated or noisy resident, but it is easily missed in a quietly confused, apathetic resident or a resident 108 P S y C H I AT R I C C O N S U L TAT I O N I N L O N G - T E R M C A R E with psychomotor retardation who is staying in his or her room. Underlying dementia, impaired vision, and being older than 80 have also been associated with the underdiagnosis of delirium (Inouye et al. 2001). For many residents, delirium may be the only manifestation of a serious medical problem (e.g., the sudden onset of a change...