René Descartes’s illustration of dualism. Inputs are passed on by the sensory organs to the epiphysis in the brain and from there to the immaterial spirit.

Mind-body dualism seems alive and well in the land of mental health. I am still surprised how often someone will say, “well that’s not a biological depression.” Meaning that it is the kind of depression that can be understood as a result of events in that person’s life, or that it can be treated effectively with therapy, or that it can’t be treated biologically.

If only life were that simple. But it isn’t.

Another reminder that you can’t draw a neat line and separate “psychology” and “biology” comes from a just published article that finds that cognitive-behavioral therapy (CBT) appears affects gene expression and changes the size of the hippocampus (a key part of the brain involved in memory) in patients with posttraumatic stress disorder (PTSD).

PTSD has profound effects on the brain’s cortisol system (a part of the overall stress response system), and it has been shown to reduce activity of a specific gene that regulates the cortisol receptor –  FKBP5.

In the study, the patients with PTSD had much lower levels of activity of this gene (what you would expect) as well as decreased volumes of the hippocampus and medial orbitofrontal cortex. 

However, after receiving  CBT, the researchers found that this abnormality was somewhat corrected.  FKBP5 expression in the patients with PTSD went up. And after the CBT treatment, hippocampal volumes in patents and control subjects were equal – meaning that therapy had completely reversed the abnormally low volumes of people with PTSD.

The researchers concluded –

Clinical improvement in individuals with PTSD was associated with increased expression of FKBP5 and increased hippocampal volume, which were positively correlated.

In other words, the biology of the brain is changed by effective therapy.

Take that René Descartes!