I have worked with people suffering from Alzheimer's disease for 14 years on a specialist community based team and used aromatherapy for the past 4 years on some very anxious clients. Although qualified in reflexology I have never used this. However, I see no reason why this should not be helpful as many people have insight into their memory problems in the early and mid stages of the illness which caused enormous stress, worry and anxiety and anything which assist in alleviating this could prove very helpful to them. When anxious we all become more forgetful, lose confidence and generally do not cope as well as we normally do - this goes for Alzheimer's sufferers also but usually the disease gets the blame. You may find it helpful to do a gentle foot massage first then work on all the stress alleviating reflexes. Build up the session time gradually until a full session can be given. It is vital to check and keep checking non verbal communication to ensure client has understood what you are doing, or intend to do, work slowly and be very calm, people with Alzheimer's can missinterpret what is going to happen to them and then become very frightened.
I hope this is helpful