ACTION , a 24-week , prospective , randomized , parallel-group , double-blind study in patients with severe Alzheimer 's disease ( AD ) , demonstrated significant efficacy of 13.3 mg/24 h versus 4.6 mg/24 h rivastigmine patch on the Severe Impairment Battery ( SIB ) and Alzheimer 's Disease Cooperative Study-Activities of Daily Living scale-Severe Impairment Version ( ADCS-ADL-SIV ) .