Paratonia or gegenhalten is classified as a form of hypertonia with an involuntary variable resistance (i.e. reduced ability of a muscle to stretch) during passive movement (i.e. a movement without effort). Paratonia develops during a period of dementia and the degree of effect is dependent upon the disease's progress. Paratonia was classified very recently by experts, and is unrelated to the much more typical spasticity associated with spastic diplegia and similar forms of cerebral palsy.