The science provides some explanatory power as to why certain therapies may be effective. For example, Cognitive Behavioral Therapy (CBT) helps patients to identify how certain errors in their thinking and certain maladaptive behaviors they exhibit helped generate and/or help perpetuate their disorders, as well as the interconnection between these cognitive distortions and the behavioral manifestations of their disorder. CBT also involves helping patients to develop mindfulness of their interoceptive experiences (the physiologic states that accompany various states of emotional distress), such that they are better equipped to differentiate their feelings from facts.
The neurological mechanism of action of CBT can best be understood in terms of modulating neural plasticity in various neural networks (e.g. the Default Mode Network, fear processing networks, etc.), for this, therapy is thought to utilize neural plasticity (the brain’s natural ability to change its wiring patterns) to reduce activity in neural networks that are generating the patients’ sadness, fear, anxiety, or anger (and the associated cognitions and behaviors), and to enhance activity in networks that represent healthy coping strategies, which can both reduce excessive maladaptive neural activity and increase adaptive neural activity (leading to improved valence of emotions and function in the various domains of life). Through repeated exercises and homework, the patient can learn to take some voluntary control over brain circuits that represent their cognitive distortions and maladaptive behaviors, which had been strengthened by conditioning from the individual’s history of thinking and behavior, as well as the ways the individual was taught to think and behave by parents and other important people in their lives.
In the words of famous neuroscientist Donald Hebb, “Neurons that fire together, wire together.” Thus, the conditioning that led to abnormal neural circuit activity can be recognized, and new patterns of thinking and behavior can be strengthened through conditioning that installs healthier patterns through the mechanisms of neural plasticity (e.g. changes in number of synapses for communication between neurons within a network and number/sensitivity of the neurotransmitter receptors on the postsynaptic neurons). These changes in neural circuit activity correlate with the changes in intensity of symptoms that a patient experiences when, for example, a therapist helps lead an individual with PTSD through Cognitive Processing Therapy (CPT) or Prolonged Exposure (PE), with a weakening of trauma memory intensity, sensitivity to cues that remind of trauma, and faulty beliefs based on feelings of hopelessness and helplessness.