Because cognitive and behavioral changes characterize all three D’s, it can be difficult to diagnose delirium, delirium superimposed on dementia (DSD), or depression. Inability to concentrate, with resulting memory impairment and other cognitive dysfunction, can occur in late-life depression. The term pseudodementia has been used to describe the cognitive impairment that may accompany depression in older adults (see Chapter 22).

Delirium is characterized by an acute or subacute onset, with symptoms developing over a short period of time (usually hours to days). Symptoms tend to fluctuate over the course of the day, often worsening at night. Symptoms include disturbances in consciousness and attention and changes in cognition (memory deficits, perceptual disturbances). Perceptual disturbances are often accompanied by delusional (paranoid) thoughts and behavior. In contrast, dementia typically has a gradual onset and a slow, steady pattern of decline without alterations in consciousness (Voyer et al., 2010).

Dementia, delirium, and depression represent serious pathology and require urgent assessment and intervention (Fletcher, 2012). However, changes in cognitive function in older adults are often seen as “normal” and not investigated. Any change in mental status in an older person requires appropriate assessment. Knowledge about cognitive function in aging and appropriate assessment and evaluation are keys to differentiating these three syndromes. Table 21-1 presents the clinical features and the differences in cognitive and behavioral characteristics in delirium, dementia, and depression.

It is important to attend to these concerns by establishing rapport and developing a therapeutic relationship, ensuring comfort, accommodating for physical impairments such as hearing and vision loss, creating an environment free of distractions, and putting the person in the best environment to ensure that performance is truly reflective of ability. The challenge is to stress the importance of the assessment without creating undue anxiety. Timing is also important, and cognitive assessments should not be conducted immediately upon awakening from sleep, or immediately before and after meals or medical diagnostic and therapeutic procedures (Braes et al., 2008). It is wise to remember that what seems to be a routine procedure to health professionals can be very intimidating for an older person, especially one who is ill or frail.

The development of delirium is a result of complex interactions among multiple causes. Delirium results from the interaction of predisposing factors (e.g., vulnerability on the part of the individual due to predisposing conditions, such as cognitive impairment, severe illness, and sensory impairment) and precipitating factors/insults (e.g., medications, procedures, restraints, iatrogenic events). Although a single factor, such as an infection, can trigger an episode of delirium, several coexisting factors are also likely to be present. A highly vulnerable older individual requires a lesser amount of precipitating factors to develop delirium (Inouye et al., 1999; Voyer et al., 2010).

The exact pathophysiological mechanisms involved in the development and progression of delirium remain uncertain, and further research is needed to understand its neuropathogenesis. Delirium is thought to be related to disturbances in the neurotransmitters in the brain that modulate the control of cognitive function, behavior, and mood. The causes of delirium are potentially reversible; therefore accurate assessment and diagnosis are critical. Delirium is given many labels: acute confusional state, acute brain syndrome, confusion, reversible dementia, metabolic encephalopathy, and toxic psychosis. The correct terminology is delirium.

Delirium is a prevalent and serious disorder that occurs in elders across the continuum of care. Estimates are that delirium may affect up to 42% of hospitalized older adults and as many as 87% of older adults in intensive care units (ICUs) (Marcantonio et al., 2010; Sweeny et al., 2008). Older people who have undergone surgery and those with dementia are particularly vulnerable to delirium. The prevalence of delirium is as high as 65% after orthopedic surgery, particularly hip fracture repair (Rigney, 2006). Among older people experiencing cardiac surgery, as many as 20% to 25% experience delirium, affecting even those without any documented preoperative cognitive impairments (Clarke et al., 2010). A 16% delirium rate in patients newly admitted to subacute care has been reported (Marcantonio et al., 2010).

The incidence of DSD ranges from 22% to 89% (Tullmann et al., 2008). Older patients with dementia are three to five times more likely to develop delirium, and it is less likely to be recognized and treated than is delirium without dementia. DSD is associated with high mortality among hospitalized older people (Bellelli et al., 2008). Changes in the mental status of older people with dementia are often attributed to underlying dementia, or “sundowning,” and not investigated. This is particularly significant because about 25% of all older hospitalized patients may have AD or another dementia (Voelker, 2008). Delirium can accelerate the trajectory of cognitive decline in individuals with AD. Despite its prevalence, DSD has not been well investigated, and there are only a few relevant studies in either the hospital or community setting.

Delirium is a medical emergency and one of the most significant geriatric syndromes (Waszynski & Petrovic, 2008). However, it is often not recognized by physicians or nurses. Studies indicate that delirium is unrecognized in 66% to 84% of patients (Pisani et al., 2006; Balas et al., 2007). A comprehensive review of the literature suggested that “nurses are missing key symptoms of delirium and appear to be doing superficial mental status assessments” (Steis & Fick, 2008, p. 47). Cognitive changes in older people are often labeled confusion by nurses and physicians, are frequently accepted as part of normal aging, and are rarely questioned. Confusion in a child or younger adult would be recognized as a medical emergency, but confusion in older adults may be accepted as a natural occurrence, “part of the older person’s personality” (Dahlke & Phinney, 2008, p. 46).

Factors contributing to the lack of recognition of delirium among health care professionals include inadequate education about delirium, a lack of formal assessment methods, a view that delirium is not as essential to the patient’s well-being in light of more serious medical problems, and ageist attitudes (Kuehn, 2010a; Waszynski & Petrovic, 2008). Failure to recognize delirium, identify the underlying causes, and implement timely interventions contributes to the negative sequelae associated with the condition (Tullmann et al., 2008; Kuehn, 2010a). Clearly, education and attitudes about older people must be addressed if we want to improve care outcomes for the growing number of older adults who will need care.

The risk of delirium increases with the number of risk factors present. Identification of high-risk patients, risk factors, prompt and appropriate assessment, and continued surveillance are the cornerstones of delirium prevention. More than 35 potential risk factors have been identified for delirium. Among the most predictive are immobility, functional deficits, use of restraints or catheters, medications, acute illness, infections, alcohol or drug abuse, sensory impairments, malnutrition, dehydration, respiratory insufficiency, surgery, and cognitive impairment. Unrelieved or inadequately treated pain significantly increases the risk of delirium (Irving & Foreman, 2006). Medications account for 22% to 39% of all delirium, and all medications, particularly those with anticholinergic effects and any new medications, should be considered suspect. Invasive equipment, such as nasogastric tubes, intravenous (IV) lines, catheters, and restraints, also contribute to delirium by interfering with normal feedback mechanisms of the body (Box 21-1).

Delirium is categorized according to the level of alertness and psychomotor activity. The clinical subtypes are hyperactive, hypoactive, and mixed. Box 21-2 presents the characteristics of each of these clinical subtypes. In non-ICU settings, approximately 30% of delirium is hyperactive, 24% hypoactive, and 46% is mixed. Because of the increased severity of illness and the use of psychoactive medications, hypoactive delirium may be more prevalent in the ICU. Although the negative consequences of hyperactive delirium are serious, the hypoactive subtype may be missed more often and is associated with a worse prognosis because of the development of complications such as aspiration, pulmonary embolism, pressure ulcers, and pneumonia. Increased hospital stays, longer duration of delirium, and higher mortality have been associated with hypoactive delirium.

Delirium has serious consequences and is a “high priority nursing challenge for all nurses who care for older adults” (Tullmann et al., 2008, p. 113). Delirium results in significant distress for the patient, his or her family and significant others, and nurses. Delirium is associated with increased length of hospital stay and hospital readmissions, increased services after discharge, and increased morbidity, mortality, and institutionalization, independent of age, coexisting illnesses, or illness severity (Witlox et al., 2010).

Recent research indicates that older adults are vulnerable to the development of accelerated cognitive decline irrespective of the severity of their illness or the length of their hospital stay, making accurate cognitive assessment and prevention and treatment of delirium a priority (Wilson et al., 2012). Delirium is also associated with lasting cognitive impairment and psychiatric problems that may persist after discharge and interfere with the ability to manage chronic conditions (Cole & McCusker, 2009; Hain et al., 2012; Lindquist et al., 2011). Screening all older adults before they leave the hospital may help to identify those in need of specific transitional care (see Chapter 3) with more frequent follow-up after hospitalization (Lindquist et al., 2011). Further research is needed to determine the reasons for the long-term poor outcomes, whether characteristics of the delirium itself (subtype or duration) influence prognosis, and how the long-term effects might be decreased.

Several instruments can be used to assess the presence and severity of delirium. To detect changes, it is very important to determine the person’s usual mental status. If the person cannot tell you this, family members or other caregivers who are with the patient can be asked to provide this information. If the patient is alone, the responsible party or the institution transferring the patient can provide this information by phone. Do not assume the person’s current mental status represents his or her usual state, and do not attribute altered mental status to age alone or assume that dementia is present. All older patients, regardless of their current cognitive function, should have a formal assessment to identify possible delirium when admitted to the hospital (see the Evidence-Based Practice box).

The Mini-Mental State Examination, 2nd Edition (MMSE-2) is considered a general test of cognitive status that helps identify mental status impairment. Although the MMSE-2 alone is not adequate for diagnosing delirium, it represents a brief, standardized method to assess mental status and can provide a baseline from which to track changes (see Chapter 7). Several delirium-specific assessment instruments are available, such as the Confusion Assessment Method (CAM) (Inouye et al., 1990), NEECHAM Confusion Scale (Neelon et al., 1996), and the CAM-ICU (Ely et al., 2001), an instrument specifically designed to assess delirium in an intensive care population.

Assessment using the MMSE-2, CAM, and NEECHAM should be conducted on admission to the hospital, throughout the hospitalization for all patients identified at risk for delirium, and for all patients who exhibit signs and symptoms of delirium or develop additional risk factors (Steis & Fick, 2008). Results of a study (Waszynski & Petrovic, 2008) suggested that the CAM was useful in identifying delirium in hospitalized adults, and nurses found it very helpful in identifying changes in cognitive functioning. As a result of these findings, the CAM was made a customary part of the daily flow sheet.

When a patient is identified as having delirium, reassessment should be conducted every shift. Documenting specific objective indicators of alterations in mental status rather than using the global, nonspecific term confusion will lead to more appropriate prevention, detection, and management of delirium and its negative consequences. Findings from assessment using a validated instrument are combined with nursing observation, chart review, and physiological findings. Delirium often has a fluctuating course and can be difficult to recognize, so assessment must be ongoing and include multiple data sources.