Childhood Trauma, Drug Abuse Linked in Brain Study

It has long been widely accepted that early childhood sexual abuse can predispose an individual to later substance abuse. But how?

Now, a new study combining brain imaging with information gathered from a questionnaire assessing symptoms of subjective distress and discomfort provides evidence of a neuroanatomical mechanism by which early childhood trauma could lead to drug abuse or other behavioral problems.

In the study, published in the January issue of Psychoneuroendocrinology, Carl Anderson, PhD., and colleagues at McLean Hospital, in Belmont, Mass., found that repeated sexual abuse in childhood may be correlated with changes in blood flow and function in a key region of the cerebellum, known as the cerebellar vermis.

At the same time, they found that those changes were significantly related to scores on a questionnaire used to rate symptoms of irritability in the limbic system of the brain, known to be involved in regulation of emotions, attention, and judgment.

Anderson and colleagues used functional magnetic resonance imaging to analyze resting brain blood flow in the cerebellar vermis of 24 subjects, aged 18 to 22.

Eight of the subjects had a history of childhood abuse; the other 16 were control subjects.

The questionnaire, called the limbic system checklist-33 (LSCL-33), was developed at McLean Hospital to assess symptoms of temporal lobe epilepsy. The questionnaire contains 33 questions assessing factors such as the frequency of paroxysmal somatic disturbances, brief hallucinatory events, visual disturbances, automatisms, and dissociative disturbances. Specific symptoms cited in the questionnaire include the feeling of something crawling on the skin, a feeling of someone being behind you, and a sinking feeling in the stomach.

They found a strong correlation between childhood sexual abuse, blood flow to the cerebellar vermis, and scores on the LSCL-33. Anderson and colleagues suggest that childhood abuse may impair the development of the cerebellar vermis, rendering abused individuals less able to manage and control symptoms of discomfort and irritability.

“Overall the abused subjects had lower blood flow in the vermis than controls, which suggests to us in a general way that there is some kind of damage to the structure,” Anderson told Psychiatric News. “Damage to the vermis certainly could increase those irritability symptoms and may interfere with judgment, so that you seek out drugs and do what you have to do to get them.”

In support of the hypothesis, Anderson and colleagues also found in a sample of 537 college students that those who frequently abused drugs had much higher LSCL-33 scores than college students who did not abuse drugs. Drug-abusing college students also had higher levels of depression and anger-irritability, though an elevated LSCL-33 score was most strongly associated with substance abuse.

Anderson said the study provides compelling evidence of the clinical usefulness of the LSCL-33 questionnaire for predicting drug abuse or other behavioral problems, including suicidal intention. “It seems like a good and unusual way to screen for these disorders, by asking about subjective experience rather than simply looking for symptoms using the DSM-IV,” he said.

More important, the new findings suggest the centrality of the cerebellar vermis in what he calls “emotional coordination”—regulating and modulating a host of behavioral responses long believed to be controlled by the limbic system.

“All of this suggests a whole new way to conceptualize drug-abuse susceptibility,” Anderson told Psychiatric News. “It really was surprising the profound interaction the cerebellum has with all these functions and how susceptible it is to trauma. You could imagine this part of the brain is the center of emotional coordination. If it is damaged developmentally, there may be a whole sequence of problems associated with poor judgment and lack of attention.” ▪