By Stephen Beech via SWNS
People whose mothers had Alzheimer’s disease are more likely to develop dementia, suggests new research.
The study shows that whether a person inherits the risk of Alzheimer’s from their mother or father influences the risk of biological changes in the brain that lead to the disease.
Factoring in sex-specific parental history could be important in helping to identify adults at heightened risk of dementia, say scientists.
American researchers analyzed levels of amyloid – a protein linked to Alzheimer’s disease – in 4,400 cognitively unimpaired adults aged 65 to 85.
They found increased amyloid in those who reported that their mothers had symptoms of Alzheimer’s.
Increased amyloid levels were also found in those with a history of the disease on both sides of their family and in those whose fathers had an early onset of symptoms.
Study senior corresponding author Dr. Hyun-Sik Yang, a neurologist at Mass General Brigham, Boston, said: “Our study found if participants had a family history on their mother’s side, a higher amyloid level was observed.”
Dr. Yang, who is also a physician investigator of Neurology for the Mass General Research Institute, teamed up with other Mass General Brigham researchers and scientists from Vanderbilt and Stanford University for the study.
He said previous smaller studies have investigated the role family history plays in Alzheimer’s disease.
Some of those suggested maternal history represented a higher risk of developing Alzheimer’s.
However, the research team wanted to revisit the question with cognitively normal participants and access to a larger clinical trial data set.
Participants were asked about memory loss symptom onset in their parents.
Researchers also asked if their parents were ever formally diagnosed or if there was autopsy confirmation of Alzheimer’s disease.
Dr. Yang said: “Some people decide not to pursue a formal diagnosis and attribute memory loss to age, so we focused on a memory loss and dementia phenotype.”
The team then compared the answers and measured amyloid in the participants.
They found maternal history of memory impairment at all ages and paternal history of early-onset memory impairment was associated with higher amyloid levels in the asymptomatic study participants.
The team also found that having only a paternal history of late-onset memory impairment was not associated with higher amyloid levels.
Study first author Dr. Mabel Seto, a postdoctoral research fellow, said: “If your father had early onset symptoms, that is associated with elevated levels in the offspring.
“However, it doesn’t matter when your mother started developing symptoms – if she did at all, it’s associated with elevated amyloid.”
Dr. Seto, who has also worked on other projects related to sex differences in neurology, says the results of the new study are “fascinating” because Alzheimer’s tends to be more prevalent in women.
She said: “It’s really interesting from a genetic perspective to see one sex contributing something the other sex isn’t.”
Dr. Seto also noted that the findings were not affected by whether study participants were biologically male or female.
Dr. Yang says one limitation of the study is some of the participants’ parents died young, before they could potentially develop symptoms of cognitive impairment.
He said social factors such as access to resources and education may have also played a role in when someone acknowledged cognitive impairment and if they were ever formally diagnosed.
Co-author Professor Reisa Sperling, a neurologist at Mass General Brigham, said the findings could soon be used in clinical translation.
She added: “This work indicates that maternal inheritance of Alzheimer’s disease may be an important factor in identifying asymptomatic individuals for ongoing and future prevention trials.”
