Patients diagnosed with Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) were found to have a mortality rate more than three times higher than the general population, according to researchers in Sweden.
The 10-year follow-up study, titled “Relative survival in patients with dementia with Lewy bodies and Parkinson’s disease dementia,” was published in the journal PLOS One.
DLB is a neurodegenerative disorder caused by the accumulation of alpha-synuclein protein clumps, leading to physical and cognitive damage.
Years of research identified a link between the diagnosis of dementia and increased mortality. But the mortality levels greatly depend on dementia type, gender, and study design.
In the general population with dementia, late diagnosis, male gender, the existence of multiple coexisting conditions (comorbidities), and functional disability have been linked to shorter survival.
A research team from Skåne University Hospital in Malmö, Sweden, studied the survival of patients with PDD and DLB compared with the general population. To better understand survival in these groups, the team identified predictors of excessive mortality.
Researchers retrospectively studied 177 patients diagnosed with PDD or DLB from 1997 to 2014 at the Memory Clinic in Malmö. Data collected included demographics, time of first visit, time of diagnosis, comorbidities, apolipoprotein E (APOE) genotyping — a test used to assess a person’s susceptibility for Alzheimer’s disease — and the mini-mental state examination score at the time of diagnosis.
Of the 177 patients included in the study, 131 had DLB, while 46 were diagnosed with PDD. All these patients had at least one comorbidity due to the diagnosis of dementia.
A total of 143 patients (81%) had died by the time of follow-up, with a median survival of 4.1 years.
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At a five-year follow-up, the mortality ratio — the ratio between the number of PDD/DLB patients’ deaths over the number of deaths in the general population — was 3.02, and at 10 years, it was 3.44, indicating that PDD and DLB patients have mortality rates more than three times higher than the general population.
Researchers also found that survival was worse if the patients were diagnosed at a younger age, were female, and showed lower scores on the cognitive test.
A more detailed analysis revealed higher mortality in DLB patients who were positive for the APOE test, but not in PDD patients who tested positive in APOE.
This retrospective study demonstrated a higher mortality rate in patients with PDD and DLB compared with the general population 10 years after the diagnosis of the disease.
Also, younger patients, females, and those who tested positive for APOE are linked to excess mortality.
“In conclusion, mortality in patients diagnosed with Lewy bodies and Parkinson’s disease dementia is over three times higher in patients during a ten-year follow-up, compared to persons in the general population unaffected by the disease,” the researchers wrote.
“Excess mortality is found primarily in younger patients, females and carriers of APOE. Further research is required regarding survival and possible interventions, including disease-modifying treatments, to improve care and prognosis for these patients,” they added.