Poor early-life mental health may jeopardize later-life physical health, according to a new study led by a University of Michigan researcher.

The study, published in the journal JAMA Network Open, indicates that people who experience psychiatric conditions when they are young are likely to experience excess age-related physical diseases when they are older.

Leah Richmond-Rakerd, U-M assistant professor of psychology, and colleagues found that this association cannot be explained by preexisting physical illness; they ruled out the possibility of reverse causation in which having a physical illness precipitates mental health problems. Prior studies had not taken this into account. This association is present across different mental disorders and different physical diseases, she said.

The researchers conducted a nationwide hospital-register study of 2.3 million New Zealanders—aged 10-60 years at baseline—followed across three decades (1988 to 2018). They tested whether individuals with mental disorders are at increased risk for subsequent chronic physical diseases and premature mortality.

Richmond-Rakerd and colleagues collected information about hospital admissions for different mental disorders, such as substance use disorders, psychotic disorders, mood disorders, anxiety disorders and self-harm behavior. In addition, researchers collected information about hospital admissions for different chronic physical diseases, ranging from coronary heart disease to cancer.

Across the 30-year period, individuals with mental disorders were more likely to develop subsequent physical diseases and they also died earlier than people without mental disorders, the study showed. They also experienced more medical hospitalizations, spent more time in hospitals for physical-disease treatment and accumulated more associated health care costs. These associations were present across all age groups and in both men and women.

The findings indicate that addressing mental health problems in early life might be a window of opportunity for preventing future physical diseases, Richmond-Rakerd said. They also suggest the importance of joined-up services, or integrated care.

“Our health care system often divides treatment between the brain and the body,” she said. “Integrating the two could benefit population health.”

Richmond-Rakerd said they chose New Zealand because there it is possible to link hospital registers and other administrative databases for the entire population of the country.

The study’s co-authors are Stephanie D’Souza and Barry Milne of the University of Auckland, Avshalom Caspi and Terrie Moffitt of Duke University and King’s College London.

This research was supported by grants AG032282 and AG049789 from the National Institute on Aging and grant MR/P005918 from the U.K. Medical Research Council. Additional support was provided by NIA grant P30 AG034424 through the Duke Population Research Institute, National Institute of Child Health and Development grant P2C HD065563 through the Duke Population Research Center, NIA grant P30 AG028716, and the Jacobs Foundation.

More information:

• Study: Longitudinal associations of mental disorders with physical diseases and mortality among 2.3 million New Zealand citizens
• Leah Richmond-Rakerd