Cognitive bias modification (CBM) offers the potential of a cheap and accessible way to help people overcome common and debilitating mental health problems, specifically anxiety disorders and depression.
This excellent, well-conducted meta-analysis of CBM trials with children and adolescents by Cristea and colleagues suggests that CBM does not work (Cristea et al, 2015). Should we pack up the training apparatus and have a look for something else? On the face of it yes.
However, there are some features of the current research that suggest that better designed trials and development of the method as an adjunct to other forms of treatment may yet offer benefit.
To understand some of the limitations of the trials reported in this review and why the conclusion of the review may be too negative, it is important to have a grasp of the basics of CBM.
- What are Cognitive Biases?
- What is Cognitive Bias Modification and why might it be the basis for a new treatment approach?
Cognitive biases are characteristic of people with depression and anxiety disorders. The evidence is particularly strong for the anxiety disorders. People who are anxious pay more attention to events or things that are frightening or threatening than people who are not anxious. This is an attentional bias.
So for example, someone with a phobia of spiders devotes more of their attentional resources to looking for spiders. They are vigilant to spiders; if there is a spider around they will notice it. They might also be more likely to spot other bugs and creepy crawlies and mistake them for a spider.
Depressed people have a tendency to see themselves, the world, and the future as negative. They make cognitive errors and are biased towards seeing the negative rather than the positive side of things. It is easy to make errors in interpreting the world because is busy and full of information; much of the information is vague, incomplete or ambiguous and we have to work to make sense of it.
For example, take this ambiguous scenario: ‘You are on the beach and you notice the weather about to change’. Is the weather improving or deteriorating? In experimental tests, depressed people are more likely to decide that it is about to rain than people who are not depressed. They demonstrate a negative interpretation bias.
Cognitive bias modification
Depressed and anxious people have cognitive biases but these may not be causally related to the disorder. However, seminal experiments by Mathews and Mackintosh (2000) showed that people (not depressed or anxious), who were trained to interpret ambiguous information in a negative way, became significantly more anxious. Thus cognitive biases may be causally related to anxiety. Therefore if cognitive biases could be eliminated or reversed this may alleviate anxiety.
This groundbreaking work was the basis for Cognitive Bias Modification as a possible intervention for anxiety disorders. CBM is based on the original experimental paradigm developed in the laboratory. There are two main forms; Attentional Bias Training (ABT) and Interpretation Bias Training (CBM-I). The link between the original experiments and depression is less clear.
The meta-analysis by Cristea and colleagues was based on a comprehensive, careful literature search. The majority of the 23 studies identified were published in 2013 or 2014 demonstrating that this is very much an emergent literature.
Outcomes of interest were anxiety and depression symptoms and cognitive biases. Studies aimed to modify interpretation and attentional biases in similar number.
Most participants were not recruited from a clinical service and in most studies they received just one session of CBM.
The methodological review suggests that most studies included under 60 participants and failed to control for several sources of bias.
- CBM interventions reduced interpretation biases in children and adolescents even after only one training session
- CBM interventions did not alter attentional biases
- CBM had a small effect on anxiety symptoms, but no effect on depression symptoms.
The authors suggest two alternative explanations for the lack of positive effects of CBM. The first is that CBM does change cognitive biases but this is not translated to a reduction in symptoms. This may be due to many reasons including insufficient opportunities to generalise CBM training to real life situations. The implication of this is that further developmental work could improve the translation of the training element of CBM to real on-line, ‘hot’, emotionally contaminated situation.
Their second explanation is that the observed change in cognitive biases is spurious and reflects the demand characteristics of the research setting. Cristea and colleagues suggest that participants have been influenced by the enthusiasm of researchers. However, as at least 50% of the studies had a well-conducted double blind it is difficult to explain how it is that only participants in the experimental groups and not those in the placebo control groups were influenced.
Correctly, in my view, the researchers identified many methodological problems associated with these studies. In relation to the standards we expect for RCTs of health care interventions, including psychological therapies, the majority of these studies fell short.
But there is the rub. CBM has only very recently emerged from experimental cognitive psychology laboratories. Many of the studies in this meta-analysis were conducted in an academic, not a clinical context. The majority were not funded or designed to meet the standards required of a formal clinical trial. The translation of CBM training to ‘real life’ settings has not been considered or developed. If we reject CBM on the basis of this meta-analysis we may commit a Type II error.
CBM requires appropriate translational research before we dismiss it completely. What we require are properly funded, designed, and managed RCTs, with a plausible intervention, a population who have both cognitive biases and symptoms of depression or anxiety, and a method of generalising CBM training to real life and assessing it in that context.
In the meantime, we might be wise to moderate our enthusiasm for the potential benefits of CBM. It is hardly plausible that CBM is a complete treatment but it may offer specific benefits or augment traditional psychological therapies.
Cristea, I. A., Mogoașe, C., David, D. and Cuijpers, P. (2015), Practitioner Review: Cognitive bias modification for mental health problems in children and adolescents: a meta-analysis. Journal of Child Psychology and Psychiatry. doi: 10.1111/jcpp.12383 [Abstract]
Mathews, A. and Mackintosh, B. (2000) Induced emotional interpretation bias and anxiety. Journal of Abnormal Psychology, 109, 602-515. [PubMed abstract]