But overall, people with dementia have higher mortality than others

Non-Alzheimer’s disease (non-AD) dementias were associated with higher mortality rates and shorter life expectancies than Alzheimer’s disease (AD) dementias, according to results from a systematic review and meta-analysis.

Although dementia conferred a higher mortality risk overall, people with non-AD dementia had a 1.33 times greater rate of all-cause mortality and a mean 1.12 year shorter survival after diagnosis than those with AD, reported Che-Sheng Chu, MD, of Kaohsiung Veterans General Hospital in Taiwan, and co-authors Lancet Healthy Longevity.

“The main findings are that people living with dementia showed a 5.90 times larger HR for all-cause mortality rate compared with individuals without dementia, and the HR for all-cause mortality increased to 17.88 in people living with Lewy body dementia,” Chu and colleagues wrote.

“Developing tailored treatment and rehabilitation programs for different types of dementia is important for mental health providers, patients, and their families,” they added.

The researchers combined data from 78 English-language studies, including cohort (prospective or retrospective) or cross-sectional studies reporting survival times from dementia diagnosis or onset with baseline and follow-up evaluations. The analysis included 63,125 people with dementia and 152,353 without dementia.

Four dementia types were included in the study: AD dementia, vascular dementia, Lewy body dementia (including Parkinson’s disease dementia, dementia with Lewy bodies, and Lewy body variant of AD), and frontotemporal dementia (including behavioral variant, progressive non-fluent aphasia, semantic dementia, progressive supranuclear palsy, and corticobasal degeneration).

Compared with people who did not have dementia:

  • People with any type of dementia had a higher mortality rate (HR 5.90, 95% CI 3.53-9.86).
  • Mortality risk was highest for Lewy body dementia (HR 17.88, 95% CI 5.87-54.46), followed by frontotemporal dementia (HR 15.26 95% CI 4.34-53.69), vascular dementia (HR 5.03, 95% CI 1.63-15.51), and AD (HR 3.70, 95% CI 1.99-6.88).

Compared with AD, vascular dementia and Lewy body dementia—but not frontotemporal dementia—were associated with a higher mortality rate. “Importantly, the findings of mortality rate (hazard ratio and rate ratio) were robust for all non-AD dementias versus AD, without significant age-related moderator effects,” the researchers wrote.

In an accompanying editorial, Julien Dumurgier, MD, PhD, and Séverine Sabia, PhD, both of Université de Paris in France, noted the authors provide “useful insights to show that mortality associated with non-AD dementias is higher than that seen in AD dementia.”

But these findings should be interpreted with caution, they pointed out.

Previous studies mainly used diagnostic criteria for dementia subtypes on the basis of clinical evaluation only, the editorialists noted. “Neuropathological studies have shown that the specificity of the clinical criteria used for AD dementia diagnosis is around 70%, leading to many false positives, with patients wrongly diagnosed to have AD although having another dementia subtype,” they wrote.

Another peril of interpretation is pathologic complexity. “Co-pathologies nearly always exist in cases of AD, particularly associations with Lewy body dementia and cerebral amyloid angiopathy brain lesions,” they wrote.

In the meta-analysis, the mean age at diagnosis was about 73 overall: 74-75 for AD, vascular dementia, and Lewy body dementia, and 64 for frontotemporal dementia.

After diagnosis, the mean survival time for people with AD was 5.8 years. Compared with those with AD, individuals with frontotemporal dementia had 1.01 year shorter survival after diagnosis. But mortality rate did not significantly differ.

“Importantly, people with frontotemporal degeneration might have a younger age at onset and diagnosis than people with AD, and thereby the mortality rate after diagnosis might be attenuated during the follow-up period,” the researchers wrote.

People with vascular dementia and Lewy body dementia had a shorter survival after diagnosis compared with AD (1.33 years and 1.01 years shorter, respectively) and larger risks for all-cause mortality compared with AD (HR 1.26, 95% CI 1.12-1.41; and HR 1.45, 95% CI 1.25-1.68, respectively).

Mean age at death in people with any non-AD dementia was lower than that of people with AD (mean difference –1.76, 95% CI –2.67 to –0.85). Mean age at death for all dementia patients was 77.6. For AD it was 78.6; for vascular dementia, 77.0, for Lewy body dementia, 79.1, and for frontotemporal dementia, 68.2.

There is an urgent need to better understand the natural history of dementia subtypes and to identify corresponding prognostic factors, the editorialists emphasized. “In the near future, biomarker-based epidemiology will hopefully help to better understand the complex interplay involved in the various proteinopathies associated with dementia,” they wrote.

Limitations of the meta-analysis included small sample sizes and number of studies available for Lewy body dementia and frontotemporal dementia. In addition, some studies based dementia diagnosis on clinical assessment, which lacked specificity.

  1. Non-Alzheimer’s disease dementias were associated with higher morality rates and shorter life expectancy than Alzheimer’s disease dementias.

  2. Overall, people with dementia showed a 5.90 times larger HR for all-cause mortality rate compared with individuals without dementia.

Paul Smyth, MD, Contributing Writer, BreakingMED™

This work was not funded.

Chu declared no competing interests.

Dumurgier and Sabia declared no competing interests.

Cat ID: 130

Topic ID: 82,130,730,130,33,361,192,925