I adapted the following from a talk I gave during my rotation with the Center for Child Protection at Penn State Hershey. Most of the information was derived from a recent review by Teicher and colleagues in Nature. It’s got great pictures but I don’t think I can legally reuse them so I’m gonna try to go without.
Basically, maltreatment and neglect during childhood turn out to be tremendously important in affecting the brain’s wiring and can lead to the development of psychiatric illness later in life. The surprising part, to me, was that the brain is changed so dramatically that MRI scans of the anatomy are affected. This is impressive because MRI can only detect fairly large changes (i.e. not microscopic rearrangements of neuronal appendages). In addition, there are clear changes in the functional response and the regional connectivity of the brain.
The most important message I took away from my readings on the subject was that abuse and neglect lead to specific “Ecophenotype” changes. That is, withstanding abuse leads to specific brain changes that depend on the type of abuse and the severity/duration of that abuse, and that these changes are unique to that experience. Basically, if you get depression and you were abused as a child, your brain doesn’t look the same as someone who got depression without a history of abuse. There’s also evidence that people with a history of abuse will respond to therapy differently than people who weren’t abused. This could lead to important changes in the way psychiatrists and the various clinical therapists deal with mental health diagnoses in this population.
From a research standpoint, it’s fascinating to look at the work that’s been done because it still doesn’t seem to be clear whether abuse leads to “toxic” changes – the brain changing because of an overwhelming stress – or adaptive changes – the brain changing because it’s protecting the user from a hostile environment. It’s very possible that the changes are part toxic and part adaptation, and that factors like type and severity of abuse affect the relative balance of these.
In brief, the literature shows that the changes in the brain depend on path through which the abuse happens. If you’re abused verbally, the auditory cortex changes, and the white matter connections in certain language areas of the brain (the arcuate fasciculus, for example, which connects areas associated with speech production and recognition) show signs of breakdown. If you see domestic abuse, the visual association cortex shows decreases in grey matter volume, and white matter tracts that connect visual and emotional processing areas show signs of breakdown. If you’re a victim of childhood sexual abuse, the grey matter volume in visual cortices and sensory cortices show decreases in volume, and the amount of cortical real estate available for genital sensations is decreased. In short, it seems that the brain tries to dampen down pathways that led to traumatic information getting around.
Without getting too deep into detail here, there were a few other interesting points. First, female brains seem to be more resistant to these changes compared to male brains. Whether this is some kind of hormonally mediated effect and whether it’s due to selective pressure (females are more often targeted by abuse and it’s likely that this has been the case well into evolutionary history) remain unknown. Also, one of the major findings that had been associated with depression, the decrease in hippocampal volume, seems to be specific to maltreatment and not specific to depression itself. This leads me to wonder how much of our psychiatric neuroimaging is drawing incomplete conclusions by not controlling for maltreatment.
There’s also a lot of interesting connection in the neurobiology between maltreatment and psychiatric illness later in life. For instance, areas like the anterior cingulate cortex, dorsolateral prefrontal cortex, and orbitofrontal cortex that are affected by maltreatment and neglect have been associated with addiction, emotional regulation, and decision-making. This provides some concrete reasoning for focusing on abuse prevention and treatment as a way of preventing substance use disorders. It also provides some mechanisms for psychiatric disorders that are strongly correlated with an abuse history, like borderline personality disorder.
I’ve only picked out a few of the major points, and I strongly recommend reading the review linked above, but hopefully I’ve been able to raise a little awareness about the importance of childhood trauma in mental health. It’s still not clear how much these findings will respond to treatment, but they will give us research tools to gauge the effectiveness of our therapies and medications, and they may give forensic psychiatrists more tools to support claims of emotional or sexual abuse, which classically don’t leave the same amount of physical evidence that juries get with physical abuse or prolonged neglect.