When meditation goes wrong Although it has been claimed that meditation does help in several ways, I have read on the Internet that there are cases where psychotic episodes, schizophrenia and suicide tendencies arise after meditation retreats.

Where I have read that this has happened is in Goenka's Vipassana retreats, which are 10 days long retreats. In particular, the only way to start at Goenka's retreats is first with a 10 days retreat.

I did one of those retreats without any unhealthy consequences, but I do confess that during the retreat I was kind of 'watching' myself to avoid any unhealthy episode.


Is there any explanation to this unhealthy responses to meditation retreats?
Is it clear why this happens?
Is there any way to minimize chances to get that wrong ?


In articles of Vipassana Research Institute it is kind of stated that the main source of this problems is that meditators have tried 'other traditions'. Is this a credible scientific answer?

Some references I found on the web:


Mental Health and Intensive Meditation Retreats
Meditation-Induced Psychosis
For Whom May Participation in Mindfulness-Based Stress Reduction Program be Contraindicated?
Psychiatric Complications of Meditation Practice
Terrible and Traumatic Experience at Goenka Retreat This one is quite an informal blog. I have found that it is frequently cited.
The Potential Downside To Vipassana. Again, an informal blog.
Things can go wrong in meditation. Some of the are as follows:


If you are not equanimous, i.e., you are reacting to different situation thus creating negativity. This can accumulate to an extent this might be very dangerous.
The basis of your meditation is greed, hatred or delusion. There are some techniques where the basis is this hence can easily go wrong. You have to be very careful and have a teacher to guide you if you do this type of meditation. E.g. in Kasina meditation you develop some attachment to the device. This should be very subtle but incorrectly practicing this can lead to an imbalance. In foulness meditation if you practice too much you might become polar to the other end where you even dislike your self and attempt suicide. This has happened in Buddha's time also.
Meditation you are area of different fears and other phobias and you closely be aware of them. This can result in imbalance of the mind if you are not strong and steadfastly equanimous. This can start tipping you over to the wrong direction.
If you strive way too hard always mindful of your progress and what you achieve you are continuously creating negativity hence you can fall into depression and anxiety. You should always do meditation for without attachment to the outcome or progress. You have to be balanced and equanimous.
You are trying to concentrate too much. This leads to disappointment when you fail. You are then accumulating negativity.
Meditation brings new experiences and sensations. If you react to them will cause problems as you are creating negativity.
You should be mindful of any polarity you have (temperament) you have and be sure you stop a particular type of samatha meditation when you are neutral if you do samatha
You have be be extremely mindful of the 5 hindrances and defilements and further be mindful that no Tanha or Upadana is in play. Sometimes you might be inadvertently developing some of these. If this continues you will go out of control so make sure you are on track. E.g. if something you are doing meditation is making you irritated, if you do not notice it soon enough and make amends to properly practice this will become stronger and can lead to depression. If you have doubts you this will have proliferation of thinking and logic followed by restlessness.
You have to be equanimous when Sankara comes up. Meditation shakes up Sankara. This means if you have something like mild depression, the intensity of this will also increase, as more and more Sankara comes up. The plus side is sooner it passes away better you become as this will eventually pass away.
Also we have built in to our self some form of ego defence mechanisms. Letting go of ego or perception of I or self can also cause lot of trauma. Best is to stay put, being equanimous and without reacting as reacting will cause more conditioning. 


What is needed to be done is (so things don't go wrong):


you have to always be equanimous
you have the right concentration and awareness, i.e., not based in a slightest trace of attachment, hate, delusion and always be mindful of the arising and passing of sensation with 1) not reaction (equanimous) 2) looking at the 3 marks of existence
stick to Sathipattana and Anapana if you do not have a well experienced teacher
alway be mightful where any negativity arises even in meditation, i.e., you reaction to sensation / feelings
sensation / feeling is as part of us (5 aggregates), it also appears in the 4 noble truths (dukkha is also a feeling), dependent origination, Satipatthana. If you do not give adequate emphasis to this then you might not be practicing the right type of awareness or concentration. (see: Vedanā in the Practice of Satipaṭṭhāna)




One VRI reference I found where other techniques were discouraged: My experiences with Goenkaji. Here what is discouraged is the practice of Mantra and Tantra in the same time as practicing Vipassana. Though statistical / clinical trials may have not been done to the extent of drug approvals, this perception may have been formed based on experience. So to avoid danger it is best to accept it at face value.

Also see:


The Importance of Vedana and Sampajanna
The Discourse Summaries
Discourses on Satipatthana Sutta
The Great Discourse on the Establishing of Awareness
Answer https://buddhism.stackexchange.com/a/3774/295 to question Are the results of positive Kamma good from a Buddhist&#39;s perspective or good from a &quot;Samsaric&#39;s&quot; perspective? (unrelated but might be of some insight)
What can go wrong in Mindfulness Therapy as used in Clinics? (Related question)