The Migrating Mind: New Studies Unlock Impact of Immigration on Mental Health

John Watson

Disclosures

May 18, 2017

The mass migration that's characterized the young, chaotic 21st century to date is captured in numbers befitting its imposing scale. It is estimated that 244 million people (3.3% of the world's population) live outside their country of origin,[1] of whom 65 million were forcibly displaced as a result of ongoing conflict and persecution—an all-time high for that figure.[2]

The multitudes contained within that 244 million flout easy categorization, encompassing skilled office workers freely walking through borders opened to them by global trade, as well as refugees from active conflicts risking their lives in arduous midnight crossings of the Mediterranean Sea. Research suggests, however, that both groups are connected by a higher risk for mental health disorders, such as depression, anxiety, posttraumatic stress disorder (PTSD), and somatic disorders.[3,4]

In recent months, new data have appeared that potentially illuminate how these risks, and the various experiences of migration, play out in the human brain. They come at a time when the climate toward immigrants and refugees has grown increasingly hostile in many countries, and highlight the importance of developing effective clinical interventions to help combat growing social stressors.

Migration and Psychosis

Studies conducted in multiple nations have reported a higher incidence rate of psychosis among immigrants, particularly among ethnic minority populations.[5,6,7,8,9,10] What was missing from this puzzle was how this risk might manifest itself at a biological level, a piece that may have fallen into place with a recent study in the journal Schizophrenia Bulletin.[11]

"Usually, social scientists look to social factors, and biological scientists such as myself look into biological factors," said study investigator Romina Mizrahi, MD, PhD, director of the Focus on Youth Psychosis Prevention clinic and research program at the Centre for Addiction and Mental Health (CAMH) in Toronto. "That's why this study is novel, because we looked into how the social world may affect brain function—specifically, how immigrants were releasing dopamine in the brain, which we know is altered in psychosis."

Researchers in Canada and the United Kingdom conducted complementary case/control studies assessing dopamine function in immigrants and nonimmigrants. The Canadian portion included 23 high-risk persons, 9 antipsychotic-naive patients with schizophrenia, and 24 healthy volunteers, whereas the UK portion included 32 immigrants and 44 non-immigrant British person. The study reported that regardless of their clinical status, immigrants had significantly elevated striatal stress-induced dopamine release and dopamine synthesis capacity compared with nonimmigrants.

"There are several factors that might be playing a significant role in this, such as the effects of discrimination, social isolation, and resilience. These really haven't been investigated in the context of brain science," said Mizrahi. "Other researchers around the world are trying to see whether the brains of those having those types of experiences are responding differently, and perhaps by doing so are increasing the risk for psychosis."

Refugees and PTSD

In a separate study whose results were presented at the American Psychosomatic Society's annual meeting in late March,[12] researchers analyzed 66 Syrian refugees within 1 month of their arrival in the United States. Those with PTSD symptoms also exhibited decreased methylation of the methyl CpG-binding protein 2 gene (MECP2), which regulates the stress-dependent gene programming that controls the activity of the hypothalamic/pituitary/adrenocortical axis .

We found that it's not the total amount of trauma but a specific kind of trauma that makes people more likely to develop PTSD.

According to principal investigator Bengt B. Arnetz, MD, PhD, MPH, MScEpi, chair of the department of family medicine at Michigan State University, this was the first large case study to look at refugees who were recent arrivals. He and his colleagues are currently testing MECP2 levels in other populations to confirm the link.

"We found that it's not the total amount of trauma but a specific kind of trauma that makes people more likely to develop PTSD," he said. "Having a threat to your own life and insufficient resources to sustain your health, and being under extreme conditions, such as lacking food or shelter, were the two most important factors that could occur before they arrived in the United States."

The patients also had unique environmental factors that may have played a role in overexpression of MECP2. Arnetz said many refugees are exposed to high amounts of lead by the conditions of war, as well as the use of leaded gasoline in the region, which also can lead to overactivation of this gene.

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