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
Their findings suggest that managing vascular risk
factors—controlling diabetes and hypertension—may reduce or delay the risk of
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
firstname.lastname@example.org or follow the magazine on Twitter @ProviderMag.