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 Poor Blood Circulation Linked To Psychosis In Patients With Alzheimer’s Disease

Researchers are honing in on what creates one of many troubling symptoms of Alzheimer’s disease: psychosis. In a recent Journal of Alzheimer’s Disease article, Canadian psychiatrist Corinne Fischer at St. Michael’s Hospital and her team report that poor blood circulation caused by cerebrovascular disease and abnormal protein deposits called Lewy bodies may be the culprits.

About half of patients with Alzheimer’s disease develop symptoms of psychosis, such as delusions or hallucinations, according to data in the field.These symptoms increase the burden on caregiving staff and lead to a more rapid functional decline and progression of the disease in patients. “We wanted to know if psychosis is because of the disease itself or something else,” Fischer said.

The usual suspects—amyloid and tau, the pernicious proteins that form plaques and tangles in patients with Alzheimer’s—have had conflicting results in prior studies as to whether these contribute to psychosis.

Fischer and her team analyzed autopsy data between 2005 and 2012 from 1,073 people found in the National Alzheimer’s Coordinating Center database, which stores information from 29 U.S. Alzheimer’s disease centers. An Alzheimer’s diagnosis can only be confirmed after death by autopsy. Of the 890 people who had been clinically diagnosed with Alzheimer’s while they were still alive, the researchers found that only 728 people had the disease, suggesting that some people had been misdiagnosed.

The researchers looked at all patients with a clinical diagnosis of Alzheimer’s disease regardless of autopsy data and all patients with a diagnosis of Alzheimer’s at autopsy regardless of clinical diagnosis. Interestingly, psychosis was strongly associated with Alzheimer pathology in the clinical group, but this effect was not present in the correctly diagnosed autopsy-proven group, suggesting the observed effects in the clinical group may have been improperly interpreted by physicians.

Regardless of whether the patients were clinically diagnosed or confirmed via pathology, psychosis correlated with another type of abnormal protein bundle, Lewy bodies, found in nerve cells of patients with Parkinson’s disease. This was not an unexpected finding since psychosis is prominent when dementia accompanies Parkinson’s disease.

What came to a surprise to the researchers was that risk factors linked to blood vessel problems—such as high blood pressure, diabetes, and smoking history—and cerebral injuries related to small vessel disease (subcortical arteriosclerotic leukoencephalopathy) appeared to be strongly tied to psychosis.

Their findings suggest that managing vascular risk factors—controlling diabetes and hypertension—may reduce or delay the risk of psychosis.

Meanwhile Fischer and her group are trying to unravel another mystery: what disease(s) afflicted the misdiagnosed patients.

Jackie Oberst is Provider’s managing editor. Email her at or follow the magazine on Twitter @ProviderMag​.

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