Comorbidity of Schizophrenia and Cocaine Abuse: Phenomenology and Treatment

Marc L. Copersino, MA, Mark R. Serper, PhD


Medscape Psychiatry & Mental Health eJournal. 1998;3(2) 

In This Article

Effect of Cocaine on the Cognitive Function of Schizophrenic Patients

Since initial recognition of the disorder, schizophrenia patients have been observed to show marked cognitive dysfunction. Researchers have consistently found that patients with schizophrenia manifest significant deficits in attention and memory. Similarly, chronic cocaine abuse is associated with attention and memory dysfunction. The neurocognitive deficits associated with chronic cocaine abuse have thus far received only modest attention. Recent evidence, however, points to sustained brain perfusion deficits and consequent neuropsychological compromise among chronic cocaine abusers. The severity of cognitive impairment caused by cocaine abuse has been positively correlated to its frequency and intensity of use. However, research suggests that, like patients with schizophrenia, chronic cocaine users show neurocognitive deficits that remain stable over time, and may be observed regardless of the duration of abstinence.[2] It therefore appears likely that cocaine exacerbates existing cognitive impairment in schizophrenia.

To date, the effects of cocaine abuse on cognitive functioning in schizophrenic individuals remain largely unexplored. Preliminary results from our laboratory suggest that comorbid patients manifest cognitive impairment on a task requiring sustained attention and concentration (using the Continuous Performance Test, or CPT), and difficulties with attention and long-term recall (as measured by the California Verbal Learning Test).[7]

To summarize, evidence suggests that cocaine use among comorbid patients worsens the severity of hallucinations and delusions, and deepens anxiety and depression. The psychostimulant properties of cocaine appear to temporarily diminish negative symptoms. Negative symptoms refer to a constellation of symptoms reflecting a diminution of normal functioning. This may include, but is not limited to, symptoms of anxiety and depression. This may be differentiated from positive symptoms that reflect an excess of functioning, beyond what may be considered normal. However, acute cocaine administration appears to have no attentional or memory benefits, with the results of a preliminary study suggesting that comorbid patients demonstrate impaired attentional and memory performance, as compared to cocaine abuse or schizophrenia patients alone.


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