The odd hallucinations, after Aricept has been removed from your mom's medication regime, could be related to withdrawal from this medication. However, it seems for most patients who suddenly stop
taking Aricept, the decline is more related to cognitive functioning and less to hallucinatons. Patients appear to rapidly progress to where they would have been in the disease process if they had never taken the drug - a sort of plummet in level of functioning and an increase in AD-related symptoms.
It appears to me, the change in her behavior may just be the course of the disease combined with the history of colon cancer. It is not unusual for people with Alzheimer's to have hallucinations when the world around them is confounding and often unrecognizable.
Often the hallucinations have a trigger and being able to identify the trigger may help you to stay ahead of the problem by stopping it before it starts. The most common area to search for a trigger is the environment around her before (or as) the hallucination is occurring. For instance:
* Are there shadows on the floor or walls caused by lighting or windows?
* Are there noises such as heating systems or air conditioning?
* Are there odors from cooking or from outdoors?
* Is it happening at the same time of day?
Sometimes it is this simple - find the environmental trigger and eliminate the hallucination by changing the cause. Light bulbs that mimic daylight are used on AD-units in community-based care to ensure there are no shadows being cast on the surroundings and staff members are trained to be tuned into environmental sounds that they may take for granted but can be disturbing to the person with cognitive-impairment. If the time of the occurrences appears to be the same general time of day, then keep mom busy during the time BEFORE the incident. You have to be a bit of a 'Sherlock Holmes' in finding the causes of hallucintions other than medication withdrawal...think of it as wearing a detective hat for a short while until you find the trigger. Chances are this will happen and the hallucinations, at worst, will be short-lived.
Do take care of you!