The Adult Brain
The study saw researchers give brain MRIs to 193 participants, aged 18 to 25. By this stage, the participants had been through several rounds of testing to qualify for the study. Once the MRIs had been completed, the researchers analyzed the hippocampus’ size of areas, comparing the results with their history. Based on well-established questionnaires, the researchers determined that those who had been maltreated, neglected, or abused had a 6% reduction in the volume of particular areas of the hippocampus.
Additionally, there were size reductions in the subiculum area of the brain. The subiculum relays signals from the hippocampus across other areas of the brain, which includes the dopamine system. The dopamine system is the brain’s reward center. A reduction in the brain’s subiculum area is associated with schizophrenia and drug abuse.
Animal experiments have shown that high levels of exposure to cortisol, the stress hormone, can shrink the hippocampus. Particularly in two key developmental periods, between the ages of 3 and 5, as well as the ages of 11 and 13. Cortisol levels prevent neuron growth in the hippocampus, leading to shrinkage in the adult human brain.
While small amounts of cortisol, and bouts of short-term stress, are harmless- too much can weaken the immune system, damage the heart, and wreak havoc on mental health.
Childhood abuse sufferers are under severe stress, both during the abuse itself, as well as in the years following as the survivor attempts to live with the fallout. People who have a history of child abuse are also more likely to suffer with chronic pain, which is another issue related to stress. Emotional support is vital in making victims feel safe and reduce stress levels.
Diseases Based in the Brain
Decreases in hippocampus volume have been linked with schizophrenia, anxiety, depression, and other psychiatric disorders. High levels of stress during vital brain development periods, due to childhood maltreatment and abuse, can cause the decrease in hippocampus volume.
The hippocampus region of the brain is home to a lot of receptors for cortisol. Cortisol interacts with the receptors in these neurons to affect their development. The neurons will respond by shrinking, or by failing to make new neurons.
Its these brain changes that can result in mental illness. This explains why childhood abuse has been highly associated with drug addiction and depression. High cortisol levels are damaging, leaving the dopamine system discombobulated and dysregulated. When the dopamine system is dysregulated the likelihood of a psychological illness, or drug abuse, is much higher.