Twenty intervention studies (n=33) were included in the review; the number of participants in each study ranged from 1 to 4.
Antecedent interventions (4 studies, n=4): all 4 studies investigating the effect of antecedent interventions, such as environmental enrichment, choice or supported mealtime routine, reported positive results in favour of these interventions. One study also found a weaker response for an environmental enrichment intervention in favour of soft toys compared with hard toys.
Multi-component interventions (4 studies, n=4): all 4 studies using multi-component interventions, including reinforcement and response effort, found a positive response to the intervention.
Pharmacological interventions (1 randomised controlled trial, n=1): a 46% reduction in hand biting per minute was found in favour of naltrexone hydrochloride (1.5 mg/kg per day) compared with placebo in an adult male with profound disability. No serious adverse events were reported.
Interventions utilising reinforcement (2 studies, n=4): both studies found a positive effect of intervention with noncontingent access to toys (with or without parent interaction) in children with profound disability. One study found a positive response to the differential reinforcement of other behaviour (DRO) compared with an ignore condition and a noncontingent attention condition, while the other study found a negative response to DRO (changing DRO and reinforcement intervals).
Response blocking interventions (4 studies, n=11): all 4 studies found a positive effect of response blocking interventions, although one found a mixed response using a hands down, drying hands and redirection (for whole group) procedure in 3 children with profound or profound multiple disability.
Interventions utilising response effort (4 studies, n=9): all 4 studies investigating the influence of response effort, including arm restraints, flexible arm splints and soft arm splints, on hand mouthing found a positive response to the intervention.
Sensory stimulation intervention (2 studies, n=2): both studies investigated the effects of matched and unmatched stimuli or sensory stimulation using food. Both studies found a positive effect of sensory stimulation intervention.