Ayahuasca and Schizophrenia

One of the primary motivations for research into hallucinogens has been the hope that it might shed light on the cause and nature of schizophrenia. Such research is largely premised on the belief that hallucinogens generally are psychotomimetic -- that is, capable of producing a model psychosis, which allows researchers to study the mechanisms of psychosis in non-psychotic subjects. This assumption is worth challenging.

Schizophrenia is a complex disease that affects almost every area of thinking, feeling, and relating. One standard text lists the main symptoms of schizophrenia as auditory hallucinations, experiences of being controlled, delusions, disorders of thinking, and emotional and volitional changes. Similarly, a classic list of the first-rank symptoms of schizophrenia includes audible thoughts; voices heard arguing; voices heard commenting on one’s actions; the experience of influences playing on the body; thought withdrawal and other interferences with thoughts; diffusion of thought; delusional perception; and feelings, impulses, and volitional acts that are experienced by the patient as the work or influence of others. The DSM-IV diagnostic criteria for schizophrenia require at least two of the following: delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, and negative symptoms -- that is, affective flattening, alogia, or avolition.

The cognitive problems reported by schizophrenic patients include distractibility, difficulty focusing, an inability to screen out irrelevant information, feeling overloaded with too many stimuli at the same time, and problems with information processing, abstract categorization, planning and regulating goal-directed behavior, cognitive flexibility, attention, memory, and visual processing. The cardinal affective symptoms include affective unresponsiveness; emotional withdrawal; inappropriate affect; shallowness, coarsening, and blunting of affect; retardation of affect; perplexity; and anhedonia.

Now some hallucinogens can apparently mimic some of the features of schizophrenia -- primarily alterations in cognitive functions and depersonalization, including difficulty in focusing on objects, tension, changes in mood, distorted time sense, difficulty in expressing thoughts, dreamlike feelings, and visual hallucinations. Psilocybin ingestion, for example, has reportedly led to disturbances of emotion, sensory perception, thought processes, reality appraisal, and ego function. These effects included derealization, an altered sense of time and space, loss of ego boundaries, visual disturbances, difficulty in directing attention, and synesthesias.

Few of these features of schizophrenia, apart from visual and auditory hallucinations, time dilation, and synesthesias, appear to be part of the DMT or ayahuasca experience. And in schizophrenic illness, visual hallucinations occur with significantly less frequency than do auditory hallucinations, and schizophrenics suffer from thought disorders and loss of affect and insight -- none of which is true of DMT or ayahuasca.

No one can seriously claim to have produced a hallucinogenic model for schizophrenic illness as a clinical entity. Attempts to draw the analogy have proceeded by narrowing the comparison: thus, for example, researchers say that hallucinogenic experience should be compared with early and recently diagnosed rather than with fully developed schizophrenia, or with paranoid instead of undifferentiated schizophrenia, or with acute rather than with chronic schizophrenia. Such shifting ground does not inspire confidence.

And any such comparison must take both set and setting into account. As molecular pharmacologist David E. Nichols puts it, “No clinician experienced with these substances would fail to consider set and setting as primary determinants of the experience.” It is difficult to maintain that participants in, say, a Native American Church peyote ceremony are temporarily psychotic in any meaningful sense at all.

Indeed, a formal psychiatric study has shown significant differences between long-term members of the União de Vegetal (UDV), a Brazilian ayahuasca-using church, who consumed ayahuasca at least two times a month in religious rituals, and demographically matched controls who had never consumed ayahuasca -- but hardly in the direction of dysfunction. Personality testing instruments showed UDV members to be more reflective, rigid, loyal, stoic, slow-tempered, frugal, orderly, and persistent, and with higher scores on measures of social desirability and emotional maturity than controls. The ayahuasca-using participants also differed from controls as being more confident, relaxed, optimistic, carefree, uninhibited, outgoing, and energetic, and with higher scores on traits of hyperthymia, cheerfulness, stubbornness, and overconfidence. Significantly, on neuropsychological testing the UDV group demonstrated significantly higher scores on measures of concentration and short-term memory, despite the fact that many ayahuasca users reported significant psychiatric and substance abuse histories prior to their church membership.

Now, there are certainly some problems with this study. UDV worship is a structured and stable environment. Participants remain seated, with long periods of silence during which they seek self-knowledge through mental concentration, aided by ayahuasca. The ayahuasca-using study participants had to have been members of UDV for at least ten years, with at least twice-monthly -- that is, highly regular -- attendance at these services. Thus, the ayahuasca users may have been preselected for personality traits of stability, persistence, and orderliness. Moreover, while subjects and controls were matched for age, ethnicity, marital status, and level of education, there was apparently no attempt made to control for regular churchgoing, a measure on which the ayahuasca users were preselected for perfect scores, and which may well be correlated with personality traits for which they also scored high. Still, the study certainly gives no grounds to believe that long-term UDV church membership, along with concomitant twice-monthly drinking of ayahuasca, has caused any personality or cognitive detriment to its members.

One may be left to wonder what is going on here. Some authors may be engaged in covert stigmatization of the hallucinogenic experience. Others may be staking out turf -- that is, advocating their own clinical use of hallucinogens for specific therapies while disparaging their use “recreationally in unsupervised settings.” There may be other sociological reasons as well. There seem to be three different types of people involved in hallucinogen research -- those who synthesize, characterize, and consume hallucinogenic substances; those who are passionate about rat brains, state-of-the-art agonists, and beta-ray radiography of thin slides of tissue after the administration of labeled ligands; and those who are engaged in the actual care and study of persons with schizophrenia. Apparently these three groups do not talk to each other, or at least not much.