Cigarette smoking, Parkinson's disease and ulcerative colitis.

Sir: Individuals who develop Parkinson's disease are about twice as likely to have been habitual non-smokers when compared with a control population.`1 Smoking also seems to exert considerable protective effects against ulcerative colitis.46 It has been suggested that both these illnesses may be associated with inflexible, morose, inwardlooking personalities.7 One of us was struck by what was possibly an unrecognised association between these two conditions, five patients with both illnesses coming to light over a three year period. With the help of a letter expressing interest in this link which was published in the UK Parkinson's Disease Society Newsletter and further postal questionnaires and correspondence with the patients' general practitioners, 20 more people with both diseases were found. The mean age of all 25 patients (14 men, 11 women) was 62 years (range 43-79); six were in social class 1, eight in social class 2, six in social class 3, four in social class 4 and one in social class 5. In 19 the ulcerative colitis preceded the Parkinson's disease, sometimes by many years. Twenty of the patients had never smoked tobacco, three had given up 25, 21 and 10 years ago respectively; one was a very occasional pipe smoker and the other patient had smoked ten cigarettes a day all his life. The prevalence of non-smoking for an age-sex-social class matched population in the United Kingdom would be about 50%.9 Two of the ex-smokers in the study had stopped smoking at least ten years before the onset of their Parkinson's disease or ulcerative colitis; another smoked a pipe very occasionally. Eighty per cent of the patients had never smoked tobacco and only three (12%) were smoking tobacco at all at the time of onset of one or other disease. In these the quantity smoked was fairly small (15 cigarettes/day, 10 cigarettes/day and '/2