Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Medical Sciences


D. Campbell


A broad overview of the irritable bowel syndrome (IBS), with an emphasis on theoretical problems, is followed by a comparative psychophysiological study of normal subjects, psychoneurotic patients and patients with IBS. All subjects had a psychiatric interview and psychometric testing followed by measurement of activity in the rectosigmoid colon during baseline, neutral interview, stressful interview and following a meal or neostigmine (0.5 mg I.M.). Myoelectrical activity was recorded from two intraluminal bipolar suction electrodes (4 cm apart); motor activity was recorded from two intraluminal strain gauges at the same sites. The number and duration of contractions per minute were determined by inspection of the motor activity record; the frequency content of both the motor and myoelectrical records was determined using a Fast Fourier Transform (FFT) computer assisted method. Measurements were also made of severity of pain following varying degrees of distension of the rectosigmoid colon, serum gastrin and motilin levels and heart rate responses. The two patient groups were psychologically similar to each other and more disturbed than normals both at psychiatric interview and on psychometric measures of anxiety, depression and neuroticism. The IBS patients were significantly different from the neurotics only on the lie scale of Eysenck Personality Inventory (p < .05). The ratings of pain to distension of the sigmoid colon were not significantly different in the three groups (p >.05). The ISS group did not differ significantly from the neurotic group on any of the physiological measures (p >.05); during baseline the ISS group had a greater number and duration of contractions than the normals at one recording site (p <.05). We conclude that previous reports of physiological characteristics unique to ISS have resulted from a failure to control for relevant psychological characteristics and from recording and analysis deficiences. A behavioral model, capable of accounting for both the experimental findings and observed clinical features, is described.

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