Abstract
This case-study explores the benefits of an additive-free diet in a 29-year-old hyperactive adult male with severe learning difficulties and behavioural problems. Behavioural observations and records of the medication intake were taken during the four weeks of baseline and 18 weeks of diet treatment. Benefits were evident only after two months of treatment; disruptive behaviour decreased considerably and medication intake was reduced from one-and-a-half bottles of paraldehyde per week to one bottle per month. Difficulties with objective measures and adherence to the diet treatment are discussed.