Ayahuasca

The chacruna leaves contain DMT. However, when these are ingested alone, they have no effect on the body as they are rapidly broken down in the gut by an enzyme called monoamine oxidase. This is where the vines come into play—B. caapi has potent monoamine oxidase inhibitors called beta-carbolines. These allow the DMT to be absorbed by the blood and eventually cross the blood-brain barrier; DMT is one of the very few substances that can breach the blood-brain barrier.

fMRI and EEG studies on those under the influence of ayahuasca have shown that the drug lowers activity in the default mode network (DMN) of the brain. The DMN is a complex and relatively novel concept that involves the prefrontal cortex, posterior cingulate cortex, and the inferior parietal lobule. The DMN is active when we are mentally at rest, meaning when we are in a relaxed state and not thinking about anything in particular or engaged in a mental task. When we are paying attention to a particular task, signals within the DMN dampen, but when we are daydreaming, passively thinking about memories and the future and about other people, DMN activity increases. 

Higher DMN activity has been linked with mental health disorders like depression, anxiety, social phobias and schizophrenia. Negative, repetitive thoughts and rumination are some of the symptoms of depression, so it makes sense that higher DMN or baseline brain activity contributes to depressive states. (Read more: Social anxiety) 

Other than reducing activity in the DMN, ayahuasca also increases activity in the visual cortex and the limbic system, which is responsible for processing memories and emotions. This altered activity explains "trips" to a degree. The mind becomes more self-aware, but due to the decrease in activity, it is purportedly able to operate in an unencumbered manner and see the bigger picture—both in the user's personal situations and the world at large.

Users begin to feel the effects of the drug within half an hour and the whole experience can last about five hours.

The psychological and psychosocial benefits of ayahuasca are the best documented. One of the first studies on the psychological benefits of ayahuasca was undertaken in 1996. Fifteen men who had taken the drug regularly for a decade were compared with a control group. It turned out that those who had been on ayahuasca long term had elevated levels of serotonin reuptake transporters. Elevated levels of serotonin transporters is what antidepressants target—according to the study, the consumption of the drug increased the baseline of this indicator. Those who suffer from depression have low levels of the indicator. Further, this indicator is also lowered in a type of alcoholism that involves addiction. The study showed that ayahuasca could, therefore, assist with mental health and addiction disorders. 

Two decades later, a similar study with 32 participants confirmed these findings. 

Other studies have shown that the drug increases assertiveness, liveliness, reduces anxiety and increases optimism and confidence. 

Another recurring theme with ayahuasca experiences is the resurrection of forceful memories and their therapeutic effects. This provides an opportunity for self-reflection that can alter maladaptive habits. Some academicians have compared the spiritual effects of the drug to intense psychotherapy and meditation since it involves confronting the self and using these insights to bring changes in the personal sphere. 

Various longitudinal studies have shown that ritualistic treatments with ayahuasca reduced reliance on illicit drugs and helped overcome addictive thoughts about alcohol and smoking. More studies need to be done on this, however. (Read more: Drug addiction)

In an encouraging development, studies on DMT have shown that the substance may also have physiological—not just pathological—benefits. Preliminary research has shown chemicals very similar to DMT that can increase neuronal survival against oxidative stress and can regulate immune responses. Further studies have shown that DMT has broader applications in cellular growth and protective mechanisms. 

Human clinical studies have shown that ayahuasca can reconfigure immune cells that can increase antiviral and anti-tumour responses. There is also some evidence that ayahuasca can increase the number of natural killer cells with time, making it a candidate for cancer therapy as well. (DMT is not currently administered to cancer patients as an approved therapy.)

While these are incredibly interesting developments, bear in mind that studies are in preliminary stages and it will be a long time before they yield therapeutic benefits. The evidence is largely conjectural at this point. 

In any case, our understanding of psychedelics is improving and the hope is that in time it will bring both psychological and physiological benefits to humankind.

The initial effects of the substance are felt within 30 minutes of administration. Often these are accompanied by fear, confusion and paranoia. Traumatic memories can be resurrected and depress the user. Also, there is a chance of severe vomiting and diarrhoea. According to the literature, the experience is divided into phases and the spiritual phase is often reached after vomiting aggressively. The drink is highly acidic and the interactions involving serotonin receptors also activate the vomiting reflex. 

Aside from this, there is also an increase in systolic and diastolic blood pressure (high blood pressure) and pupil dilation. Cardiovascular and endocrine problems, abnormal lipid metabolism, glaucoma, and fever have been associated with ayahuasca consumption but are rare.

Drug interactions with SSRIs (selective serotonin reuptake inhibitors), MAO inhibitors (monoamine oxidase inhibitors), and ginseng can be severe. This can lead to serotonin syndrome which includes high fever, tremors, shivering, hyperthermia, palpitations, convulsions and even death. 

While the probability is low, those with a family or personal history of mental illness such as schizophrenia can have a psychotic episode and lose touch with reality for an extended period of time. 

Bad trips can be very frightening episodes for some people and can cause mental trauma at times. This likelihood is reduced if the drug is administered by a professional and is not mixed with other substances. Bad experiences and severe side effects have risen with unscrupulous "shamans" misleading tourists and administering dangerous substances.

Studies have shown no indication of dependence or addiction.