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Understanding Dementia


This is an excerpt from the book Understanding Dementia, which is meant to be a practical manual for primary care physicians and other health care professionals. Delirium is discussed briefly in Chapter 5, where causes of cognitive impairment other than dementia are considered. It is also described in more detail in chapter 8, where it is considered with other 'atypical illness presentations', such as falls. An illustrative case is also described in chapter 10, where the point is to discourage inappropriately large doses of neuroleptic medications, such as haloperidol.

Delirium is usually identified by the acute onset of new cognitive problems, with prominent attention deficits and a coexisting medical illness. Once the underlying cause is treated most of the cognitive findings should slowly improve. About half of elderly hospitalized patients with delirium have a coexisting dementia, and many supposedly normal individuals will have a progressive cognitive decline after an episode of delirium. In retrospect, families often identify pre-existing problems. Some research in delirium has demonstrated that subtle cognitive impairment may persist long after the acute event has resolved, and that the relative risk of developing dementia is increased roughly threefold in otherwise well elderly patients who experience delirium.

Delirium is recognizable by its abrupt onset and characteristic fluctuation through the course of the day. The history of a change in behaviour or function rarely encompasses more than a few days. Serial evaluations will most commonly reveal varying degrees of dysfunction, almost always accompanied by a disordered sensorium. Although agitation, often with hallucinations, misperceptions and delusions, is a common component of the delirium syndrome this 'agitated delirium' is not always seen. Not infrequently patients display what is known as an 'apathetic delirium'; sometimes referred to as being 'quietly confused'. This second presentation of delirium is more difficult to recognize, and in our experience goes almost universally unrecognized in academic acute care settings. Primary care physicians, having the benefit of frequent contact with, and an intimate knowledge of their patients, are in a much better position to identify that a change has occurred, and suspect that an apathetic delirium may be present.

Unfortunately, when the physician is not familiar with the patient, delirium can sometimes be difficult to distinguish from dementia, as was discussed in Chapter 5. The history provided by the patient's family is invaluable in the attempt to separate the two. Even if specific symptoms cannot be described the family can often provide a sense that a change has occurred. A characteristic finding in delirium which is helpful in distinguishing it from dementia is decreased attention. Despite a lack of detail and paucity of content a patient with Alzheimer's disease can carry on a conversation and attend to the interviewer. When someone is with them they will attempt to interact. Even patients in stage 6 of the FAST, who may be nearly mute and pacing , will stop long enough to be fed or changed. In contrast, the delirious patient often manifests severely impaired attention, being unable to attend to the interviewer for any period of time. The physician can quickly become frustrated as the patient appears to be paying little attention to questions or directions, and sometimes, as in patients with depression , the feelings experienced by the physician can be important clues to the patient's diagnosis . Clues from the clinical interview, other than a rapid decline in function, can be elicited from observations about aspects of attention. For example, when trying to feed the patient, do they now constantly reach past the feeder and fidget or look away? Is the patient distracted by each new sound or movement in the environment? Do they pick at themselves, or their clothes, or the physician?

Conditions to consider in the differential diagnosis include medications (prescription or over-the-counter, especially anticholinergics and sedative/hypnotics), infections (especially urinary tract or pneumonia ), congestive heart failure , metabolic causes (especially hyponatremia) or some combination of these as outlined in Table 8.3. The investigations we recommend are presented in Table 8.4.

Rockwood & MacKnight, 2001. p. 130

Rockwood & MacKnight, 2001. p.131

Treatment of delirium and other atypical illness presentations must first be preceded by the question, "Is treatment of this condition now likely to do more harm than good?" Even if the answer is yes adequate care is still required, and often the hospital is the only practical site in which to provide this care. The treatment chiefly focuses on the underlying cause. While waiting for the specific therapy to take effect supportive care, in terms of nutrition, hygiene, safety, and the avoidance of complications such as pressure sores and hip fractures, is necessary. Heavy involvement of the family in the process of hospital care is most helpful in meeting the supportive needs. The third arm of therapy (predominantly for delirium) is sedative. We only use sedatives when the delirious patient is a risk to themselves or others (not just an annoyance), recognizing that many sleepless hours constitutes a risk for the patient. The management of sedative therapy is outlined in Chapter 10.

A key concept in the evaluation of new problems occurring in dementia is that of stage congruence. The Global Deterioration Scale, similar to the FAST, gives the expected profile of patients with Alzheimer's as the disease progresses. Those who experience, early in the course of their dementia, symptoms (such as hallucinations or incontinence ) which are typically found late in Alzheimer's disease are said to have stage incongruence. Stage incongruence is most often due to another illness presenting atypically. Occasionally it is a sign that the diagnosis of Alzheimer's disease is wrong. This idea of stage congruence, while of great importance in Alzheimer's disease, has less application in the other dementias, although it mostly holds true that sudden changes are more likely due to a second problem, not the underlying dementia.

Chapter 10: Case 1
Dr Y was a 74-year-old retired professor, recently diagnosed with Alzheimer's disease. He had been started in an open-label trial of acetyl cholinesterase inhibitor and had shown a promising early response. An elective orthopaedic procedure was planned. Care was taken to optimize his medical status ahead of time. The operation proceeded uneventfully and eighteen hours postoperatively he was doing very well. In the early hours of the morning following surgery, he suddenly became confused and called out. Despite explicit consultant suggestions, he was given 5 mg of haloperidol. In the view of the housestaff and nurses who were caring for him the drug was found ineffective, as his confusion and agitation worsened. He was therefore given another 5 mg of haloperidol. A brief consultation was urgently requested the following morning.
Examination showed an extremely agitated, restless man in considerable psychologic distress. He was in four point physical restraint.

This patient is acutely confused and meets the criteria for delirium. Delirium should not be considered a psychiatric illness in which the psychotic symptoms can be treated with no further evaluation. Rather it is a sensitive sign of illness, particularly in patients who have underlying dementia.

Dr Y was transferred to our service where all psychoactive medications were stopped and his medical condition investigated. At the time of transfer he was confused and agitated, did not recognize his wife, and was incontinent of urine . The MMSE score was 0/30.

Hyponatremia was found. Treatment of this, along with the stopping of the psychoactive medications, is expected to improve his mental status, which will then allow him to participate in a rehabilitation program with the ultimate goal being discharge home with independent function.

Dr Y's mental status improved. By discharge, 12 days later, he was lucid with only minimal abnormalities on cognitive exam. Other than difficulty with stairs and the bathtub, he was independently mobile and required no assistance in activities of daily living.

This is a successful outcome of delirium, a common post-operative problem. If he had continued to be treated symptomatically without addressing the underlying causes of delirium, he may well have ended up with a permanently worsened cognitive status and more medical complications, such as pressure ulcers , aspiration and pneumonia, and falls with fractures. Not considering the medications used to treat delirium as potentially adding to the problem is, in our experience, one of the most common management errors made in hospitals.

Taken from Understanding Dementia: A Primer of Diagnosis and Management
Kenneth Rockwood & Chris MacKnight, 2001
Chapter 5, pp 93-94; Chapter 8, pp129-131; Chapter 10, pp 173 - 174


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About Dementia > Types of Dementia > Delirium
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Last updated April 17, 2014
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