Constraint-induced language therapy has its underpinnings in physiotherapy and was initially developed for use with patients experiencing limb weakness. For example, the strong arm would be immobilized so that patients would be forced to try using the paralyzed arm.
Unlike traditional therapy techniques in aphasia therapy which promote the use of multiple forms of communication (i.e.: writing, drawing, gesturing, etc.), constraint-induced language therapy forces patients to use only verbal responses which are gradually shaped into longer and more complex responses over time. This is an intensive process (generally up to 3 hours of therapy per day, 5 days per week).
Recently, researchers have started to question whether the noted benefits are the result of forcing patients to utilize verbal communication or the high intensity of treatment or both. Recent research suggests that both factors may be involved. In a systematic research review completed by Cherney et al. (2008), researchers found positive outcomes for both constraint-induced language therapy and intensive therapy protocols for individuals with non-fluent, chronic aphasia. Taken together, the researchers concluded that the benefit of constraint-induced language therapy may be in part related to its intensity. In another study, Maher et al (2006) found a positive effect of the forced language use component as well.
Clearly, more research is needed. Nonetheless, evidence is mounting that the treatment technique once restricted to physical rehabilitation may serve well in the field of communication rehabilitation.