How long you survive an α-synucleinopathy depends on which disorder struck you, according to a paper published online May 15 in JAMA Neurology. Scientists led by Rodolfo Savica and Michelle Mielke at the Mayo Clinic in Rochester, Minnesota, found that in a population-based sample, patients with α-synucleinopathies died younger than age-matched controls. The fastest killer was multiple system atrophy (MSA), followed by dementia with Lewy bodies (DLB), Parkinson’s disease with dementia (PDD), then Parkinson’s disease (PD). “These data are critical for clinicians counseling parkinsonism patients and caregivers, as it provides them with robust life expectancy estimates and may facilitate long-term care planning,” wrote Sirwan Darweesh, Erasmus MC University Medical Center Rotterdam, the Netherlands, to Alzforum.
Prior studies have reported survival rates for various parkinsonian disorders (see Elbaz et al., 2003; Driver et al., 2008; Goldstein et al., 2015); however, most of these recruited from hospitals rather than the general population, and none compared α-synucleinopathies side by side.
Savica and colleagues drew on medical records from the Rochester Epidemiology Project, which collates health data from all residents of Olmstead County, Minnesota. Between 1991 and 2010, 461 people were clinically diagnosed with a synucleinopathy accompanied by parkinsonism: 309 with PD, 81 with DLB, 55 with PDD, and 16 with MSA. Some people with MSA have a cerebellar form of disease without parkinsonism, but these patients were excluded. Each was compared to an age- and sex-matched control from the general population.
As a group, synucleinopathy patients died an average of two years younger than controls. Broken down by etiology, MSA took six years, DLB four years, PDD 3.5 years, and PD one year off a person’s lifespan. According to death certificates, neurodegenerative disease was the most common cause of death for people living with an α-synucleinopathy, listed at 32 percent. This was followed by cardiac events in 16 percent and cancer in 7 percent. Among controls, 26 percent died from a cardiac event and 18 percent from cancer. Interestingly, this adds to a growing number of studies that suggest patients with neurodegenerative disease have a lower risk of cancer (see May 2013 news; Tabarés-Seisdedos and Rubenstein, 2013).
Savica said that the difference in survival among the disorders could reflect different severities of disease and different rates and locations of α-synuclein deposition.
“The comparison of survival among different clinical phenotypes of synucleinopathies is new. It highlights the powerful effect of cognitive impairment and dementia to predict a poor prognosis across the PDD/DLB spectrum,” wrote David Irwin, University of Pennsylvania, Philadelphia, to Alzforum. “Further, there is limited data on the natural history of MSA, and this paper provides new insight into the relatively rapid progression of this disease.” He suggested that prospective studies following patients to autopsy could point to pathological variables that lead to longer or shorter survival in individual patients. Savica said his group has submitted one autopsy study for publication, and will expand on pathology in an upcoming project.
Both Irwin and Darweesh praised the population-based design. “As a result, the study’s patient sample is generally representative of the broad spectrum of underlying causes and clinical severity of synucleinopathy-associated parkinsonism in the community, ensuring that its findings can largely be generalized to similar populations,” wrote Darweesh.—Gwyneth Dickey Zakaib
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