What makes a person withdraw from the world,
stop speaking, and create his own world?

    This question is so broad that I must limit my answer to only pointing out some major areas of possible concern rather than a definitive answer.  What might be responsible could be gender related, age related, neurologically based, or what we refer to as psycho-socially based.

    Some gender based areas to look in to for females might be menopause, child birth, miscarriage, or in the case of a young teen, puberty.  Any changes in the female body can seriously challenge a woman's view of herself in critically fundamental ways, sometimes resulting in feelings of shame or embarrassment.  For men, we also need to look at puberty, loss of libido, loss of hair, declining athletic ability, retirement, layoffs, and fatherhood.  Any or all of these can create fear, anxiety, depression, shame, or embarrassment resulting in withdrawal as a protection mechanism.

    Age related issues include some of the above, such as retirement, body changes, and also loneliness, "empty nest syndrome," and bereavement (loss of friends and family).  The issue of certain death looms ever larger as one ages.  Regrets can occupy the mind and a sense of despair sets in.  The person loses his/her desire to mix with others as he/she retreats into a world of sadness.

    The possibility of neurological factors should never be casually dismissed.  We are ever changing beings.  In youth, we change toward more capacity and capability, but in old age we can, and are, often surprised at what neurological circuitry can go awry.  Dementia is one very common factor.  A person's ability to maintain a sharp short term memory can result in embarrassment and social awkwardness.  A decline or loss of driving skills can seriously affect mood.  The solution -- withdrawal from situations which expose these failings.  And neurological factors are not always age based, so even young people are vulnerable, especially when certain street drugs have been used.

    But, if the person is young and healthy, psychological and social issues tend to be the more common areas of focus.  When people withdraw, often it is the result of either anger toward others for not relating to the individual the way the individual believes that they should, or anger over the failure of the individual to live up to his/her own image/standard set for him- or herself.  Both tend to be related to self-pride.  Either I "deserve" better than what I received or, I am not what I want others, or myself, to believe about me.  In response to the first issue, the person might conclude that no one is good enough, smart enough, etc., to be worthy company and retreat into a fantasy world of revenge and/or acclamation.  The second case might result in retreating to a fantasy world where there is no fear of others noticing the shortcomings, or the individual has no shortcomings.  Solution -- avoid contact with others in the real world.