It is important to recognize that this impairment may not necessarily translate into altered decisional capacity regarding other health care decisions, such as consenting to surgery or other necessary medical interventions.9
Substance-related disorders that affect decisional capacity
Substance-related syndromes can affect mood, reality testing, and/or cognitive function, thereby directly impacting a patient’s decisional capacity. Substance-related syndromes can be divided into 2 categories: 1) disorders resulting from the direct effects of the substance, and 2) secondary disorders resulting from/or associated with substance use.
Disorders resulting from the direct effects of the substance
- Acute intoxication or intoxication delirium may be the most frequent type of temporary incapacitation. It can result from toxic levels of licit or illicit substances; alcohol is likely the most frequent offending agent. Although some individuals who are intoxicated may appear to be alert, oriented, and able to engage in lengthy conversations, the majority do not possess adequate decisional capacity.10
- Withdrawal delirium, associated with longstanding alcohol, sedative-hypnotic, or barbiturate dependence, is typically prolonged, but usually resolves, either spontaneously or with treatment. Although most deliria resolve once the underlying etiology is corrected, vulnerable individuals may experience irreversible cognitive impairment and permanent decisional incapacitation.11,12
- Severe substance-induced depressive disorders, especially if accompanied by frank psychotic symptoms or severe depressive distortions of reality, may result in decisional incapacity. Substance abuse treatment that incorporates multiple strategies, sometimes in conjunction with pharmacotherapy to manage depression, should lead to sufficient recovery and restoration of decisional capacity.
- Transient psychotic disorders such as those associated with the use of stimulants are often treatable. Patients may recover decisional capacity spontaneously or with treatment.
- Dementia is associated with substance use, particularly alcohol use.13 For a patient who develops dementia, no appreciable recovery can be expected, even with prolonged abstinence.
- Persistent amnestic disorders (eg, Korsakoff syndrome) resulting from undiagnosed or untreated severe thiamine deficiency (Wernicke’s encephalopathy). Although an isolated Korsakoff syndrome consists primarily of anterograde amnesia, these patients may experience additional cognitive impairment resulting from years of alcohol consumption or associated with other neurodegenerative processes, and therefore are sufficiently impaired and lack decisional capacity. Even in the absence of such concomitant cognitive deficits, a very severe anterograde amnestic disorder directly impacts a patient’s capacity to perform the necessary tasks required to give informed consent. The inability to consolidate information about new medical developments, treatments, and procedures, even when they are thoroughly explained by the medical team, can pose serious challenges. For example, a patient may protest to being taken to surgery because he/she does not recall signing a consent form the previous day.
- Enduring severe and treatment-refractory psychotic disorders associated with drug use, specifically stimulants, can result in permanent incapacitation similar to that seen in severe primary psychotic disorders (such as treatment-resistant schizophrenia).
Secondary disorders resulting from/or associated with substance use
- Hepatic encephalopathy may be seen in patients with advanced cirrhosis of the liver (due to hepatitis C resulting from IV drug use, and/or alcohol use). In late stages of cirrhosis, the confusional state patients experience may become severe and may no longer be reversible unless liver transplantation is available and successful. This would therefore constitute a basis for permanent decisional incapacitation.
- Human immunodeficiency virus encephalitis or dementia can result from IV drug use.
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