Hand behaviors can signal severe mental problems. Some examples are mentioned in the DSM IV diagnostic and statistical manual of mental disorders. Some of the examples mentioned are:

1 - 'hand biting' can signal AUSTISTIC DISORDERS (page 71);
2 - 'hand tapping' can signal HYPERACTIVITY (page 86);
3 - 'tactile inabilities' can signal DEMENTIA (page 149);
4 - 'trembling hands' can signal SOCIAL PHOBIAS (page 451);
5 - 'cold, clammy hands' can signal ANXIETY (page 452);
6 - 'sleeping on the hands' can signal BREATHING-RELATED SLEEP DISORDERS (page 619);
7 - 'wringling of the hands' can signal AGITATION (page 819).

But there are so many more illustrative examples available which illstrate that Sigmund Freud's former student Carl Gustav Jung (1875-1961) was very right when he wrote in 1944 the introduction of the work (titled: "The Hands of Children") presented by the German chirologist Julius Spier:

"... The totality-conception of modern biology which is based on the evidence of a host of observations and research does not exclude the possibility that hands, whose shape and functioning are so intimately connected with the psyche, might provide revealing and therefore, interpretable expressions of psychical peculiarity, that is, of the human character. ..."

(More specified guidelines will follow later)