Common Clinical Disorders Affecting Mental Status Testing

Delirium

Delirium is the most common brain-behavior disorder and the most frequent behavioral manifestation of medical disorders or physiological disruptions. It is an acute change in mental status with prominent changes in attention. There is a disturbance in level of awareness and a fluctuating ability to focus, sustain, and shift attention. These difficult additionally impair instrumental cognitive abilities. There is a spectrum of delirium from mild inattention and distraction to a lethargic and poorly responsive state.

Clinicians may fail to diagnose delirium because they fail to recognize and test for this syndrome. The elderly can have a “quiet” or subtle presentation of delirium that may go undetected. Yet, delirium occurs in 10% to 30% of medically ill patients, a clear majority of hospitalized elderly patients, and 80% or more of patients in the intensive care unit. The consequences of delirium include prolonged hospitalizations, increased mortality, high rates of discharge to institutions, severe impact on caregivers and spouses, and more than $4 billion of annual Medicare expenditures in the United States. Of particular importance is distinguishing delirium from dementia, the other common disorder of cognitive functioning. Delirium is acute in onset (usually hours to a few days), whereas dementia is insidious in onset and progressive. Delirium is an acute neurobehavioral decompensation with fluctuating attention, regardless of whether the patient has underlying cognitive deficits or dementia. In fact, the presence of underlying dementia is a major risk factor for delirium.

There are 10 essential characteristics of delirium ( Box 3.1 ):

• 1.

  Acute Onset with Fluctuating Course. Delirium develops over hours or days but sometimes over a week or more. The course progresses to daily fluctuations of attention, arousal, and other symptoms, sometimes interposed with lucid or near normal intervals. Clinicians need to examine these patients at several points in time to get an understanding of the extent and depth of fluctuations.

• 2.

  Attentional Deficits. A disturbance of attention is the defining symptom of delirium. Attention is the ability to focus mental activity on a targeted external or internal stimulus to the exclusion of others. Patients with delirium cannot consistently focus, sustain, or shift their attention to relevant aspects or events, and environmental or internal stimuli, no matter how minor, can easily distract them from the topic at hand.

• 3.

  Confusion or Disorganized Thinking. Patients with delirium cannot maintain a clear and coherent stream of thought. They are unable to perform organized, goal-directed behavior, and their speech reflects this disorganization. Their verbal output is poorly connected, often going from topic to topic in a tangential, circumlocutory, or totally unrelated manner.

• 4.

  Disturbed Arousal. Most patients have alterations in their arousal, or their readiness to react or “alert” to stimuli. This is distinct from attention and the ability to focus mental activity. Arousal refers to the ability to respond or alert; disturbances or arousal range from lethargy to stupor and coma. Most patients with delirium tend to have lethargy and decreased arousal, but some patients with delirium have increased arousal, such as those with delirium tremens. Some patients may have fluctuations that range from hypoarousal to hyperarousal.

• 5.

  Disturbed Perception. A dramatic feature of delirium, when present, are altered perceptions, particularly hallucinations in the visual sphere. These hallucinations are frequently animate, variable, and in color, and they may or may not be frightening to the patient. Other perceptual disturbances include illusions (distorted perceptions or sensations) and misperceptions or misinterpretations. Ultimately, the most common perceptual disturbances are missed perceptions, or failure to appreciate things that are going on around them.

• 6.

  Disturbed Sleep-Wake Cycle. Patients with delirium have disturbances of the normal diurnal or circadian rhythm and experience disruption of their day-night cycle. This most commonly manifests as excessive daytime drowsiness or sleeping, and sometimes wakefulness and alertness at night. There may be “sundowning,” or agitation and restlessness occurring during the night.

• 7.

  Altered Psychomotor Activity. Delirium can be hypoactive, hyperactive, or mixed in their psychomotor activity. The most common are hypoactive with psychomotor retardation and often accompanying lethargy and decreased arousal. The less common hyperactive subtype often has accompanying agitation, perceptual disturbances, and overactivity of the autonomic nervous system.

• 8.

  Disorientation and Memory Impairment. Disorientation is one of the most common findings in delirium. Disorientation is not specific for delirium, however, and it occurs in dementia and amnesia as well. Among patients with delirium, recent memory is disrupted in large part by the decreased registration caused by attentional problems. In delirium, reduplicative paramnesia, a specific memory-related disorder, results from decreased integration of recent observations with past memories. Persons or places are “replaced” in this condition. For example, they tend to relocate the hospital closer to their homes.

• 9.

  Other Cognitive Deficits. Patients with delirium have cognitive deficits in writing and in visuospatial abilities. Writing disturbance result in poorly formed letters and words and a tendency to disturbed spatial orientation or direction of written sentences or phrases. These patients also manifest difficulties with visuospatial constructions, such as drawings, and with complex visual processing, such as visual object recognition and environmental orientation.

• 10.

  Behavioral and Emotional Abnormalities. Patients with delirium may have delusions, or false beliefs, that are poorly systematized and paranoid with a persecutory content. Other patients with delirium exhibit marked emotional lability or may become agitated, depressed, or quite apathetic.