Scientists find signs of Alzheimer's in dolphin brains

ATLANTIC CITY, NEW JERSEY - AUGUST 28: Dolphins swim in the Atlantic Ocean just off the coast of Atlantic City on August 28, 2022 in Atlantic City, New Jersey, United States. With warming waters, dolphins and other mammals have been seen swimming and

A recent study published in the European Journal of Neuroscience, found that three species of dolphin showed signs of Alzheimer's disease. 

Researchers say they hope the new findings will provide greater insight into the disease and its impact on humans. 

According to the study, published earlier this month, scientists conducted postmortem studies on the three species of dolphins which were found stranded along the coast of Scotland. 

In total, 22 dolphin brains were studied in which researchers noted that the animals presented alterations in their brain chemistry, changes most commonly found in humans who have Alzheimer's. 

In a statement, Tara Spires-Jones, study coauthor said their team was "fascinated to see brain changes in aged dolphins similar to those in human (aging) and Alzheimer’s disease."

"Whether these pathological changes contribute to these animals stranding is an interesting and important question for future work," said Spires-Jones added. 

The findings follow the news that an experimental Alzheimer’s drug modestly slowed the brain disease’s inevitable worsening — but the anxiously awaited new data leaves unclear how much difference that might make in people’s lives.

Japanese drugmaker Eisai and its U.S. partner Biogen had announced earlier this fall that the drug lecanemab appeared to work, a badly needed bright spot after repeated disappointments in the quest for better treatments of the incurable disease.

Late Tuesday, the companies provided full results of the study of nearly 1,800 people in early stages of the mind-robbing disease. The data was presented at an Alzheimer’s meeting in San Francisco and published in The New England Journal of Medicine.

Lecanemab delayed patients’ worsening by about five months over the course of the 18-month study, Eisai’s Dr. Michael Irizarry told The Associated Press. Also, lecanemab recipients were 31% less likely to advance to the next stage of the disease during the study.

"That translates to more time in earlier stages" when people function better, Irizarry said.

Every two weeks, study participants received intravenous lecanemab or a dummy infusion. Researchers tracked them using an 18-point scale that measures cognitive and functional ability.

The study’s key finding: Those given lecanemab declined more slowly, a difference of not quite half a point on that scale over the 18 months, concluded the research team led by Dr. Christopher van Dyck at Yale University.

Doctors are divided over how much difference that may make for patients and families -- especially as the drug carries some worrying potential safety risks including brain swelling.

"It is unlikely that the small difference reported in this trial will be noticeable by individual patients," said Dr. Madhav Thambisetty of the National Institute on Aging, who noted he wasn’t speaking for the government agency.

He said many researchers believe a meaningful improvement would require at least a difference of a full point on that 18-point scale.

But Dr. Ron Petersen, an Alzheimer’s expert at the Mayo Clinic, said the drug’s effect was "a modest one but I think it’s clinically meaningful" -- because even a few months’ delay in progression could give someone a little more time when they’re functioning independently.

The trial is important because it shows a drug that attacks a sticky protein called amyloid -- considered one of several culprits behind Alzheimer’s -- can delay disease progression, said Maria Carrillo, chief science officer for the Alzheimer’s Association.

"We all understand that this is not a cure and we’re all trying to really grasp what it means to slow Alzheimer’s, because this is a first," Carrillo said.

But any delay in cognitive decline early on could be meaningful for "how much time we have with our loved ones in a stage of disease where we can still enjoy family and outings, vacations, bucket lists," she said.

Amyloid-targeting drugs can cause side effects that include swelling and bleeding in the brain, and lecanemab did as well. One type of this swelling was seen in about 13% of recipients. Eisai said most were mild or asymptomatic.

Also, two deaths have been publicly reported among lecanemab users who also were taking blood-thinning medications for other health problems. Eisai said Tuesday the deaths can’t be attributed to the Alzheimer’s drug.

But Mayo’s Petersen said if lecanemab is approved for use in the U.S., he’d avoid prescribing it to people on blood thinners at least initially.

The Associated Press contributed to this story.