[Chaos theory and complexity in psychiatry].

In spite of the continuing development of psychometric and apparative methods, the determination of mind has not yet been successful. This fact is due to the complexity of the nervous system, which can only be described statistically and as an epiphenomenon, just like any other biological system. Fractal geometry presented in the sixties by Mandelbrot provides the conception of fractal dimension, a numerical term allowing a more adequate description of complex systems. In many fields of medical science attempts are being made to apply this knowledge; in psychiatry, however, methodological problems still remain unsolved. For the present the necessity of a new thinking should be emphasized while trying to determine the functions and dysfunction of the mind.