Though frequency may vary, rumination typically occurs daily and may persist for many months or years. Rumination disorder has been reported in children and adults with mental retardation as well as in infants, children, and adults of normal intelligence. Among those with otherwise normal intelligence and development, rumination is most common in infants. The prevalence in adults of normal intellectual functioning is unknown because of the secretive nature of the condition and because physicians lack awareness of rumination among this population. Rumination is more common in individuals with severe and profound mental retardation than in those with mild or moderate mental retardation.
Rumination occurs in both males and females.
A male predominance has been reported by 1 case series, although this finding may not be definitive. Rumination often remits spontaneously. Rumination among adolescents and adults of normal intelligence is gaining increased recognition. Regurgitation typically begins within minutes of a meal and may last for several hours. Regurgitation occurs almost every day following most meals.