Psychosis, including delusions and hallucinations, affects about half of Alzheimer's disease patients. And researchers have set out to clarify the link between these two conditions.
Canadian researchers said they found that cerebrovascular disease -- a group of conditions that restrict the circulation of blood to the brain -- appears to play a significant role in psychosis for those with Alzheimer's.
About 19 percent of people with Alzheimer's living in the community (rather than in a nursing home) have delusions. Another 14 percent have hallucinations, the researchers said.
Psychotic symptoms among people with Alzheimer's can cause added burdens on loved ones and caregivers. These symptoms can also speed up the progression of Alzheimer's disease, the study authors explained.
For the study, the researchers analyzed autopsy data from more than 1,000 people who had been treated at 29 Alzheimer's centers in the United States between 2005 and 2012. An Alzheimer's diagnosis can only be confirmed after death by autopsy.
The research team -- led by Dr. Corinne Fischer from St. Michael's Hospital in Toronto -- said that 890 of the study patients had been clinically diagnosed with Alzheimer's disease while still alive. Of those, nearly 730 had Alzheimer's that was confirmed by an autopsy, according to the report published Jan. 5 in the Journal of Alzheimer's Disease.
The autopsies revealed that those with confirmed Alzheimer's who had been diagnosed with psychosis didn't have more physical evidence of Alzheimer's disease in their brains (such as protein deposits).
Instead, the researchers were surprised to learn that risk factors linked to blood vessel problems -- such as high blood pressure, diabetes and smoking history -- appeared to be strongly related to psychosis.
Because researchers haven't known the underlying reason for psychosis in Alzheimer's patients, they've been limited in how well they can treat the issue, the study authors explained in a hospital news release.