Clouding of Consciousness - Psychopathology

Psychopathology

In the 1817 German treatise Der Traum und des fieberhafte Irreseyn, translated as "The Dream and the feverish Insanity", Greiner first pioneered the concept of a clouding of consciousness (Verdunkelung des Bewusstseins) as the pathophysiological abnormality responsible for delirium. Clouding of consciousness is conceptualized in terms of a part of the brain regulating the "overall level" of the consciousness part of the brain responsible for awareness of oneself and of the environment. Various etiologies can "funnel" in on and disturb this common regulating part of the brain, which in turn disturbs the "overall level" of consciousness. The key idea here is an abnormality in the "regulation" of the "overall level" of consciousness, referred to also as wakefulness or arousal, as opposed to an abnormality in specific or focal parts of consciousness. Arousal may be too low, too high, or it may oscillate between the two resulting in a hypoactive, hyperactive, or mixed clinical presentation respectively. The term "wakefulness" apparently has two contradictory definitions. On one hand, it is said that wakefulness is the degree of sensory stimulation required to keep the patient awake and vigilant. On the other hand, it is said that it is possible for sufferers to be "awake" yet to still have a clouded consciousness. Paradoxically, sufferers declare that they are "awake but, in another way, not".

Performance on virtually any cognitive task may be affected. As one author put it, "It should be apparent that cognition is not possible without a reasonable degree of arousal." The most important cognitive impairment, however, is inattention. The relationship between attention and consciousness is a matter of intense debate among scholars. The subject matter of the debate, apparently, is whether one needs to be conscious (aware) of something to pay attention to it or whether one needs to pay attention to something to be conscious (aware) of it. Accordingly, some doctors say that delirium is a disorder of consciousness whereas other doctors say that delirium is a disorder of attention. Academic musings aside, the DSM-IV-TR simply links consciousness, awareness, and attention together on the same line in its description of delirium.

The sufferer's experience is apparently more profound or abstract than simply having difficulty performing cognitive tasks. Sufferers describe a "spaced out" feeling. The subjective sensation of mental clouding, described in the patient's own words as feeling "foggy", is the single most disliked component. According to the sufferer's perception, time stands completely still. Sufferers compare their overall experience to that of a dream because like in a dream consciousness, attention, orientation to time and place, perceptions, and awareness are disturbed. Barbara Schildkrout, MD, a board-certified psychiatrist and clinical instructor in psychiatry at the Harvard Medical School described her subjective experience of clouding of consciousness, or what she also called "mental fog", after taking a single dose of the antihistamine chlorpheniramine for her cottonwood allergy while on a cross-country road trip. She described feeling "out of it" and being in a "dreamy state". She described a sense of not trusting her own judgment and a dulled awareness, not knowing how long time went by.