It is likely that the sort of endlessly reflexive recursive
thoughts frequently associated with mental illness
are a symptom
of structural psychological
problems, rather than a cause of them.
Psychological studies have demonstrated amply that mental disorders, both chemical and physical, tend to produce certain aberrant (but frequently creative and insightful) patterns of thinking, and that these patterns develop according to the particular disorder involved.
For example, the work of Dr. Oliver Sacks illuminates the fascinating (and often tragic) parallels that exist between the biological effects of post-encephalitic Parkinson’s disease and the internal thought-processes of afflicted patients. Though the mental mechanisms of thought in sufferers often yield profoundly philosophical, artistic, and mathematical ideas, one should not deduce from this that these sorts of ideas (relating to temporal deconstruction, exponential fragmentation of perception, synaesthesia, and so on) precipitate mental illness.