Vascular risk factors, including a history of hypertension and diabetes, have been found to be associated with the development of psychosis in patient with Alzheimer’s disease.
About half of all patients with Alzheimer’s disease develop symptoms of psychosis, such as delusions or hallucinations, noted Canadian researchers.
“Vascular and Lewy body pathologies and vascular risk factors are important modifiers of the risk of psychosis in Alzheimer’s”
They said some previous studies had suggested they were related to the underlying causes of Alzheimer’s disease such as the protein deposits found in the brain, but equally others had found no correlation.
Their study found that risk factors for vascular disease were a major determinant of psychosis in people with Alzheimer’s disease.
Researchers led by Dr Corinne Fischer, a psychiatrist at St Michael’s Hospital in Toronto, used autopsy data from a US national database, which was collected between 2005 and 2012.
Of 890 people who had been clinically diagnosed with Alzheimer’s while they were alive, those most likely to be psychotic were those whose autopsies showed they had more physical signs of the condition, such as neuritic plaques and neurofibrillary tangles.
However, when they looked at 728 people whose autopsies confirmed they had the disease, those with psychosis did not show increased physical evidence of Alzheimer’s disease.
In both groups of patients, psychosis correlated significantly with Lewy bodies – abnormal protein aggregates found in nerve cells of patients with Parkinson’s disease.
This finding was not unexpected, said the researchers, since psychosis is prominent when dementia accompanies Parkinson’s disease.
What was entirely unexpected, they said, was the prominent role in psychosis of vascular risk factors – hypertension, diabetes, age at quitting smoking – and cerebral injuries related to small vessel disease.
“Vascular and Lewy body pathologies and vascular risk factors are important modifiers of the risk of psychosis in Alzheimer’s disease,” they stated in the Journal of Alzheimer’s Disease.