Babies born prematurely who also sustain small brain injuries at the time of birth are more likely to have lower levels of dopamine as adults, according to a new study led by researchers at King’s College London.

Dopamine is a neurotransmitter associated with motivation, attention, concentration, and finding enjoyment in life. Low levels of this chemical may lead to serious mental health conditions such as depression and substance dependence.

Although one in 10 people are born prematurely, most experience no major complications around the time of birth. However, 15-20 percent of babies born before 32 weeks of pregnancy experience bleeding in the brain’s ventricles (fluid-filled spaces). If this bleeding is significant, it can cause long-term problems.

While the exact link between birth complications and greater risk of mental health issues is still unclear, one theory states that the stress of a complicated birth could lead to increased levels of dopamine, which is also increased in people with schizophrenia.

To investigate this further, researchers from King’s, Imperial College London and the Icahn School of Medicine at Mount Sinai in New York, used a combination of positron emission tomography (PET) scans and magnetic resonance imaging (MRI) scans of the brain along with a range of psychological tests. They wanted to determine the precise changes to both chemistry and brain structure following early brain damage.

They compared three groups of people: adults who were born very preterm who sustained early brain damage, adults who were born very preterm who did not sustain brain damage and controls born at term.

“People have hypothesised for over 100 years that certain mental illnesses could be related to problems in early brain development,” said Dr. Sean Froudist-Walsh, the study’s first author. “Studies using animal models have shown us how early brain damage and mental illness could be linked, but these theories had not been tested in experiments with humans.”

‘We found that dopamine, a chemical that’s important for learning and enjoyment, is affected in people who had early brain injury, but not in the way a lot of people would have thought — dopamine levels were actually lower in these individuals,” said Froudist-Walsh.

“This could be important to how we think about treating people who suffered early brain damage and develop mental illness. I hope this will motivate scientists, doctors and policymakers to pay more attention to problems around birth, and how they can affect the brain in the long term.”

Research has shown that mental health problems often arise from a complex mix of genetic vulnerability factors combined with negative or traumatic life-experiences. Difficulties at birth may count as one of the most stressful life experiences.

“The discovery of a potential mechanism linking early life risk factors to adult mental illness could one day lead to more targeted and effective treatments of psychiatric problems in people who experienced complications at birth,” said Dr. Chiara Nosarti, the study’s joint senior author from King’s College London.

Source: King’s College London

Dopamine Seen As Link to Mental Illness for Brain-Injured Preemies