BACKGROUND PAPER

June 2016

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SUMMARY

Anosognosia is an awkward term introduced by neurologists a century ago to denote “a complete or partial lack of awareness of different neurological . . . and/or cognitive dysfunctions.” It is not the same as denial of illness. Anosognosia is caused by physical damage to the brain, and is thus anatomical in origin; denial is psychological in origin.

The late, eminent neurologist Oliver Sacks described anosognosia thus:

It is not only difficult, it is impossible for patients with certain right-hemisphere syndromes to know their own problems – a peculiar and specific ‘anosognosia,’ as Babinski called it. And it is singularly difficult, for even the most sensitive observer, to picture the inner state; the ‘situation’ of such patients, for this is almost unimaginably remote from anything he himself has ever known.

Approximately 50% of individuals with schizophrenia and 40% of individuals with bipolar disorder are estimated to have co-occurring anosognosia. It is reported to be the most common reason why individuals with schizophrenia refuse to take medication; since they do not believe that there is anything wrong with them, why should they? Awareness of illness sometimes improves with treatment with antipsychotic medication, especially clozapine.

BACKGROUND

Among neurological patients, anosognosia is seen most commonly in Alzheimer’s disease, Huntington’s disease and traumatic brain injury. Most patients with Alzheimer’s disease, for example, are aware that something is wrong early in the course of their illness but then lose all awareness of their illness as it progresses. Anosognosia is seen less commonly in patients with stroke (especially those involving the right parietal lobe) and Parkinson’s disease. Impaired awareness of illness is not a new idea for psychiatric patients either; in 1604, a character in playwright Thomas Dekker’s The Honest Whore says, “That proves you mad because you know it not.”

ANOSOGNOSIA RESEARCH SUMMARIZED

Since 1992, there have been 22 studies comparing the brains of individuals with schizophrenia with and without anosognosia. In all but two studies, significant differences are reported in one or more anatomical structures. Since anosognosia involves a broad brain network concerned with self-awareness, a variety of anatomical structures are involved, especially the anterior insula, anterior cingulate cortex, medial frontal cortex, and inferior parietal cortex. Three of the positive studies included individuals with schizophrenia who had never been treated with medications, discounting the likelihood that the observed brain changes resulted from treatment.

Earlier anosognosia research is summarized by Xavier Amador, PhD, and Tony David in their 2004 book, Insight and Psychosis: Awareness of Illness in Schizophrenia and Related Disorders.

Following is a summary of 25 studies of anosognosia in psychiatric disease, beginning from the most recent.