A major study has found that Australians who develop anorexia start fasting at an average age of 15.
The Annorexia Nervosa Genetics Initiative (ANGI) aims to identify the genes associated with anorexia. It is the largest genetic study ever to be conducted into the eating disorder.
The Australian branch of the global research project is being led by Professor Nick Martin from the Genetic Epidemiology Laboratory at QIMR Berghofer Medical Research Institute.
Professor Martin said he and his team had collected DNA samples and personal information from 3,414 Australians and 543 New Zealanders who had experienced anorexia at some time in their lives.
“We found that in both Australia and New Zealand the most common methods of weight control were fasting and exercise. These behaviours generally also started at a younger age than the use of medication or self-induced vomiting,” he said.
“Australian participants reported starting fasting at an average age of 15, while exercise started at an average age of 16 and self-induced vomiting at 17.
“The average age at which Australian participants reported starting to use diet pills and laxatives was 18.
“We didn’t find any relationship between the methods people used to control their weight and the severity of their eating disorder.”
Dr Katherine Kirk from QIMR Berghofer said that 60 per cent of Australian participants said they had experienced binge eating at some time during their illness.
“Thirty-eight per cent of Australian participants reported also experiencing bulimia nervosa,” Dr Kirk said.
“At the time of the study, 32 per cent of participants were under the care of a medical practitioner.
“Given that anorexia has the highest mortality rate of any psychiatric disorder, these figures are concerning.”
Professor Martin said the causes of anorexia were still poorly understood.
“We do know, however, that a person’s genetic make-up accounts for about 60 per cent of their risk of developing anorexia,” he said.
“It is a severe psychiatric disorder, so it’s crucial that we find out more about the causes. Our next step will be to start analysing the DNA of study participants to unravel the genetic drivers of this devastating illness.
“This is the largest sample of people with anorexia to be collected in Australasia to date. The results of this study will improve our understanding of the disorder, and how we can best care for those who develop it.”
The study has been published in this months’ edition of the Australian and New Zealand Journal of Psychiatry. It was funded by the Klarman Family Foundation and the University of Otago.