The Practice Notebook of a Psychotherapy Trainee: Why is Psychotherapy Effective?

I froze like “a deer caught in the headlights.” My clinical supervisor repeated the question: “What would be a contraindication for this medication?” A reasonable question from a clinical supervisor for a senior medical student! Only ten minutes earlier, I had reviewed the indication and contraindications of this particular medication. But when I was put on the spot, overwhelmed with near panic, nothing came to my mind! This does not happen too often anymore thanks to my personal application of  cognitive behaviour therapy (CBT), which has helped me to overcome some of my performance anxiety. Now, in my clinical practice as a resident physician in psychiatry, I regularly prescribe medication and refer patients to psychotherapists for anxiety and depression. Quite often,  psychotherapy is prescribed as a stand-alone treatment without concurrent medication.  


In this series of blogs, I am attempting to answer the questions of a novice trainee in psychotherapy. Previously I answered the question: For whom is CBT most effective? In this entry, I will answer the question:

Why is psychotherapy effective?

Dr. Timothy Strauman and his colleagues from the Department of Psychology and Neuroscience at Duke University published an overview of the theoretical framework informing research done to answer the question of why psychotherapy works (read it here). According to the authors, it is possible to examine this question in two complementary ways: the older way of behaviour sciences and the newer way of neurosciences.

Scientists from the behavioural sciences would propose that the effectiveness of psychotherapy (regardless of modality) may rely upon:

  1. The quality of the therapeutic relationship between therapist and patient or client
  2. The shared understanding of the cause(s) of distress for the patient or client
  3. The collaborative commitment to improve the patient or client’s function
  4. Teaching and learning of emotional, behavioural, interpersonal regulation strategies
  5. Improvement of self-awareness and self-understanding (insight)

Scientists from the neurosciences would propose that the effectiveness of psychotherapy may rely upon:

  1. Strengthening of regulatory activities by brain centres responsible for executive control (i.e. the prefrontal cortex)
  2. Attenuation of excessive activity in brain centres responsible for emotional processing and reactivity (i.e. the limbic region and amygdala)
  3. Brain circuitry yet-to-be elucidated are altered by “talk therapy” causing changes in thinking, feeling, and behaving.

Dr. Irene Messina and colleagues of the University of Padova were interested in testing the three proposals listed here. The authors completed a meta-analysis of 16 brain-imaging studies of brains of people who have been treated with psychotherapy for anxiety and depression (read it here). The authors were interested in identifying areas of the brain consistently changed after psychotherapy in 70 study participants in the resting state, and 65 study participants asked to do emotional-cognitive tasks while their brains were imaged. Most changes detected were inconsistent between studies due to varied methods. Significant consistencies were noted for psychotherapy-induced clusters of changes within the following examples of brain regions:

1. Relatively increased activity in the resting state:
a. Middle Temporal Gyrus
b. Inferior Temporal Gyrus

2. Relatively decreased activity in the resting state:
a. Superior Frontal Gyrus
b. Medial Frontal Gyrus
c. Inferior Parietal Lobule

(For a full list refer to Table 2 in the article here)

Most disappointingly, neither the limbic system nor the prefrontal cortex (more specifically the dorsolateral prefrontal cortex or DLPFC) was found to consistently change in activity after psychotherapy in enough samples to reach statistical significance. The authors believe that this was a limitation of the methods used in this meta-analysis rather than a true null result. The activity in the DLPFC and the limbic system are found to be modulated in multiple brain-imaging studies during both the resting state and emotional-cognitive tasks if each study were scrutinized independently.

The authors were careful to state that the study cannot be considered conclusive due to limitations such as small sample sizes, absence of control groups in many studies, variable times (pre and post-psychotherapy) between studies, and a wide range of imaging techniques and study designs. The only conclusion reached is that the neurobiological mechanisms of psychotherapy may be more complex than the postulated model of deficient top-down executive control and inappropriately over-active emotional expression. Brain circuitry yet-to-be elucidated may be altered by “talk therapy” causing changes in thinking, feeling, and behaving.

The search continues for consistent changes in neurological circuits in response to psychotherapy. As quoted in the review by Dr. Strauman, Gordon Paul posed this question in 1967: “Which [psychotherapy treatment], by whom, is most effective for a particular individual with a specific problem under a certain set of circumstances?” Perhaps we will get closer to answering this question with the advent of sophisticated brain-imaging techniques applied to decipher the neurophysiology of psychotherapy.

We do not yet know fully why psychotherapy is effective but we are certain of its value in the treatment of mental illness.  We have over 100 years of research evidence and clinical experience to convince us that psychotherapy works in reducing distress and improving function–very often with minimal unpleasant side effects sometimes common with medications.

According to guidelines for various mental disorders, psychotherapy is evidence-based and effective treatment with high tolerability. For example, in cases of mild depression CBT or Interpersonal Therapy (IPT) are first-line stand-alone therapies supported by Level 1 evidence (two or more randomized, controlled trials having adequate number of research participants and/or meta-analysis showing consistent results). Second line therapies for mild depression with Level 1 evidence support is bibliotherapy/reading therapy. See CANMAT guidelines here.



1. Strauman TJ, Goetz EL, Detloff AM, MacDuffie KE, Zaunmüller L, Lutz W.
Self-regulation and mechanisms of action in psychotherapy: a theory-based
translational perspective. J Pers. 2013 Dec;81(6):542-53. Read it here.

2. Messina I, Sambin M, Palmieri A, Viviani R. Neural correlates of psychotherapy
in anxiety and depression: a meta-analysis. PLoS One. 2013 Sep 11;8(9):e74657.  Read it here.

3. Parikh SV, Segal ZV, Grigoriadis S, Ravindran AV, Kennedy SH, Lam RW, Patten
SB; Canadian Network for Mood and Anxiety Treatments (CANMAT). Canadian Network for Mood and Anxiety Treatments (CANMAT) clinical guidelines for the manageme of major depressive disorder in adults. II. Psychotherapy alone or in combination with antidepressant medication. J Affect Disord. 2009 Oct;117 Suppl 1:S15-25. Read it here.

In the next blog of this series, I will examine the question of whether “client” or “patient” of psychotherapy is more appropriate.


The views expressed in these blogs are the author’s own and not necessarily reflective of those of Psychotherapy Matters.  Copyright © 2015

Vicky Nguyen
Vicky Nguyen

Vicky is a psychiatrist and recent graduate from the Northern Ontario School of Medicine (NOSM). She completed her PhD and MD training at the University of Toronto. Her research interests are directed at promoting innovative practices and policies to address sub-optimal wait times, access, equity, and quality of health care services for disadvantaged populations in Ontario. She is certified to provide IPT and CBT. She is trained to provide other types of therapy including DBT, and Psychodynamic Psychotherapy.

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