Para psychotic troubles in Mentally Handicapped Persons (particularly in Down syndrome)-Clinical examples of M.H.P. which had no trouble until their 25-40 (years) except their intellectual defect and then, slide in psychiatric or para psychiatric behaviour. It starts with loosing vital aim and long lasting soliloquy. Then starting with an emotional frustration. Special reflexion about pseudo intellectual deterioration considered as, almost Alzheimer which is often a kind of familial contage of loosing vital impulse. It seems obvious for M.H.P. that realising their handicap without being prepared nor psychologically accompanied lead a possible trigger for loosing psychological control. Sports or leisure activities with other M.H.P. are most inefficient but a prevention often appears possible.