Delirium history and symptoms
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vishal Khurana, M.B.B.S., M.D. [2]
Overview
History and Symptoms
- Thorough history including:
- Incoherent speech
- Memory difficulties
- Disorientation
- Level of attention
- Conversations with family and/or caregivers of patient
- Performance of abbreviated mental exam
Risk Factors
- Age
- Cognitive impairments
- Psychiatric conditions
- Severe chronic medical illness
Commonly co-occurring mental symptoms, with a note on severity
Since delirium may occur in very many grades of severity, all symptoms may occur with varying degrees of intensity. A mild disability to focus attention may result in only a disability in solving the most complex problems. As an extreme example, a mathematician with the flu may be unable to perform creative work, but otherwise may have no difficulty with basic activities of daily living. However, as delirium becomes more severe, it disrupts other mental functions, and may be so severe that it borders on unconsciousness or a vegetative state. In the latter state, a person may be awake and immediately aware and responsive to many stimuli, and capable of coordinated movements, but unable to perform any meaningful mental processing task at all.
Inability to focus attention, confusion and disorientation
The delirium-sufferer loses the capacity for clear and coherent thought. This may be apparent in disorganised or incoherent speech, the inability to concentrate (focus attention), or in a lack of any goal-directed thinking.
Disorientation (another symptom of confusion, and usually a more severe one) describes the loss of awareness of the surroundings, environment and context in which the person exists. It may also appear with delirium, but it is not required, as noted below. Disorientation may occur in time (not knowing what time of day, day of week, month, season or year it is), place (not knowing where one is) or person (not knowing who one is).
Cognitive function may be impaired enough to make medical criteria for delirium, even if orientation is preserved. Thus, a patient who is fully aware of where they are and who they are, but cannot think because they cannot concentrate, may be medically delirious. The state of delirium most familiar to the average person is that which occurs from extremes in pain, lack of sleep, or emotional shock.
Because most high level mental skills are required for problem solving, including ability to focus attention, this ability also suffers in delirium. However, this is a secondary phenomenon, since problem-solving involves many sub-skills and basic mental abilities, any of which may be impaired in a delirious patient.
Memory formation disturbance
Impairments to cognition may include temporary reduction in the ability to form short-term or long-term memory. Difficult short-term memory tasks like ability to repeat a phone number may be continuously disrupted during a delirium, but easier short-term memory tasks like repeating single words, or remembering simple questions long enough to give an answer, may not be impaired. Reduction in formation of new long-term memory (which by definition survive withdrawal of attention), is common in delirium, because initial formation of (new) long-term memories generally requires an even higher degree of attention, than do short-term memory tasks. Since older memories are retained without need of concentration, previously formed long-term memories (i.e., those formed before the period of delirium) are usually preserved in all but the most severe cases of delirium (and when destroyed, are destroyed by the underlying brain pathology, not the delirious state per se).
Abnormalities of awareness and affect
Hallucinations (perceived sensory experience with the lack of an external source) or distortions of reality may occur in delirium. Commonly these are visual distortions, and can take the form of masses of small crawling creatures (particularly common in delirium tremens, caused by severe alcohol withdrawal) or distortions in size or intensity of the surrounding environment.
Strange beliefs may also be held during a delirious state, but these are not considered fixed delusions in the clinical sense as they are considered too short-lived (i.e., they are temporary delusions). Interestingly, in some cases sufferers may be left with false or delusional memories after delirium, basing their memories on the confused thinking or sensory distortion which occurred during the episode of delirium. Other instances would be inability to distinguish reality from dreams.
Abnormalities of affect which may attend the state of delirium may include many distortions to perceived or communicated emotional states. Emotional states may also fluctuate, so that a delirious person may rapidly change between, for example, terror, sadness and jocularity.