HARRISONBURG, Va. — “The Mennonite game” — tracing the genealogy of a new acquaintance to find a common ancestor — might be a fun pastime for people with Mennonite backgrounds, but such a relatively shallow gene pool is also helpful for understanding the neurobiology behind bipolar disorder.
An ongoing National Institute of Mental Health study is enlisting the participation of people of Anabaptist heritage — such as Eastern Mennonite University alumna Bev Miller — who have or are related to people with bipolar disorder. Also known as manic-depressive illness, it tends to run in families.
Miller, who lives in Wauseon, Ohio, is one of the study’s nearly 1,000 participants, many of whom live in areas of the U.S. highly populated by Mennonites. The study also includes participants from Mennonite communities in Brazil and Canada.
Four decades ago, Miller learned she had bipolar disorder when manic episodes and deep depression abruptly ended her teaching career and led to multiple extended hospitalizations. She now manages her illness with medication.
In recent years, she has shared her story as an offering of hope to others struggling with the disorder. She said her openness has been met with appreciation and has allowed others to share.
Miller also promotes participation in the NIMH study. Understanding the genetic roots of the disorder has given her a sense of peace — she didn’t cause her illness — and a mission.
“Success of this study will not only serve our denomination but will be a gift to the world,” she wrote in an article in The Mennonite.
Less is more
There isn’t sufficient data to say if the disorder, which affects about 2 percent of the general population, is more or less prevalent among Anabaptists, said Francis McMahon, chief of the NIMH Intramural Research Program’s Human Genetics Branch.
However, it is very clear that genes are the major cause. About three-quarters of the risk for bipolar disorder can be explained by inherited genes. Many people whose families have historically been part of Anabaptist groups such as the Amish or Mennonites have something special to offer researchers: less genetic complexity than the general population.
The NIMH study is not the first to look at bipolar disorder in Mennonites and Amish. EMU alumnus Abram Hostetter researched the disease in Amish for four decades beginning in the 1970s.
Many Anabaptists share common ancestors who at times experienced population bottlenecks when a portion of a group escaped persecution and resettled elsewhere, or when a group split and began new, distinct communities that then perpetuated a particular genetic code.
Because these populations’ genetic codes have fewer variants, variants that may be more prevalent in people with bipolar disorder may be more easily identified through genome sequencing.
“So far we have no definitive findings, but we have identified a number of genetic variants that do seem to be more common in people with the illness, and we’re now working on collecting more people who carry those variants as a way to establish statistical proof of the association,” McMahon said.
Participation in the study does not require a bipolar diagnosis. Researchers are also willing to screen people who think they might have it, or who have relatives with a positive diagnosis. Participants can also learn about genetic predisposition to conditions such as heart disease or cancer.
Miller hopes even more will join her in the program.
“It’s one thing Mennonites can do for the rest of the world,” she said.