Early brain injuries have lasting effect on dopamine
Premature infants with brain injuries early in life have lower dopamine levels as adults.
Thirteen million infants are born too early every year. Improved care allows many to survive, but these “preterm infants” still face an increased risk of death and many other complications. Infants born very early, before 32 weeks, are at risk of brain injury because the brain is normally still developing in the later stages of pregnancy. They also have an increased risk of developing mental health problems later in life.
Early-life brain injuries in rats cause changes in the production of a chemical called dopamine. Dopamine is a chemical messenger in the brain that reinforces rewarding behaviour. People with schizophrenia and attention deficit hyperactivity disorder (ADHD) have abnormal levels of dopamine. Changes in brain dopamine levels may explain why early-life brain injury is linked to later mental illness. But first scientists must study whether similar changes occur in humans with an early-life brain injury.
Now, Froudist-Walsh et al. use brain imaging to show that people born very early who suffered a brain injury have lower dopamine levels than other adults. Imaging techniques were used to scan the brains of 13 adults who were born before 32 weeks and who had a brain injury around birth, 13 adults born before 32 weeks without a brain injury, and 13 adults born at “full term” (around 39 to 40 weeks). Individuals with low dopamine levels reported difficulty concentrating and a lack of motivation and enjoyment in their lives. Both can be warning signs of mental health problems.
People born prematurely without a brain injury had normal dopamine levels and did not report such symptoms. More studies may help scientists understand how early brain injuries may cause brain chemical differences later in life, and how these brain changes affect individual’s mental health. They may also help scientists develop treatments to prevent or treat mental illness in people who experienced a brain injury after a very early birth.
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