When someone is diagnosed with dementia, a common question families ask is, “How much time do we have?” How long does it take for a loved one to leave? What happens after memories fade and confusion begins?
This difficult question can be difficult to answer because life expectancy after being diagnosed with dementia varies from person to person. About 3 to 7 years And it varies more or less depending on the person’s age and situation. Types of dementia they have developed.
However, in general, people with dementia tend to have shorter lifespans than otherwise healthy people. And a new study suggests that seemingly unaffected twins may be as well.
This strange association is the result of a large study of hundreds of Swedish twins, where one twin was diagnosed with dementia and the other did not.
The study also included a large-scale analysis of about 1,000 people with dementia who happened to be twins, and about 3,000 healthy people who were also twins but not necessarily siblings of the person with dementia.
Not surprisingly, people without dementia lived longer than those with dementia. Additionally, the researchers found that people with dementia live an average of seven years after diagnosis, confirming previous estimates.
Unexpectedly, identical twin pairs had similar life expectancies after one sibling was diagnosed with dementia.
The results of this study suggest that the increased risk of shortened lifespan associated with dementia may extend to unaffected twins, and may be due to genetics rather than the dementia itself or environmental factors. Questions have arisen as to the extent to which this contributes to premature death.
Chong-Yun Jang, a medical researcher at the University of California, Irvine and lead author of the study, said, “The reason people with dementia have a shorter life expectancy is because dementia has no effect on mortality.” “We thought that this was because it caused other medical conditions.” ,” she To tell.
“What we are seeing instead is that the increased risk of death is not just caused by the dementia itself, but also by the whole package of other effects that the person brings to the disease.”
The study drew data from the Swedish Twin Registry, a large cohort study of more than 45,000 Swedish twins.
Jang et al.’s main analysis included 90 pairs of monozygotic twins, 288 pairs of dizygotic twins, and zygosity unknown in which one twin had dementia and the other did not. Five sets of twins were included.
Twin research is Incredibly useful natural “experiments” Researchers can ask questions about the extent to which genetic and lifestyle factors influence a person’s health that would otherwise be impossible.
Although twins born at the same time share nearly identical genetic sequences, their environmental influences and lifestyle exposures may differ from childhood onwards, and their health may vary as well.
Researchers compared the number of years lived after one member of a pair of fraternal and identical twins was diagnosed with dementia and found that life expectancy was lower between fraternal and identical twins than between identical twins. I found that there was a big difference.
This suggests that genetic factors common to identical twins influence similarly short lifespans, but that environmental factors unique to each twin may still be playing a role. there is.
In a subsequent analysis, healthy people whose twin had dementia had a slightly higher risk of having a shorter lifespan compared to people in pairs where neither twin was diagnosed with dementia.
This suggests that the risk of reduced lifespan associated with dementia is partially familial, even among identical twin siblings, and is not solely related to the dementia itself. I am.
The researchers said, “Although identical twins who have a twin with dementia may not develop dementia themselves, they may have a shorter lifespan.” write in their paper.
Although the number of twins in this study is large, this finding could be further strengthened if replicated in another twin registry outside of Sweden. The majority of dementia cases included in the analysis had Alzheimer’s disease, so life expectancy patterns may be different for other forms of the disease.
This research Alzheimer’s Disease and Dementia: Journal of the Alzheimer’s Association.
