We asked: Is CBT – which requires complex cognitive processes – appropriate for depressed patients with severe cognitive dysfunction?
Prof Wittchen said: It depends what you understand as falling under the term CBT. There are some therapies that might be much too complex for patients to work with when they are severely depressed. But simple forms of behavioural therapies like behavioural-activation therapy can be really helpful in the most severe stages of depression.
We asked: When combining pharmacological therapy with cognitive behavioural therapy (CBT), which antidepressants are most efficacious and what is the most effective sequence of therapy?
Prof Wittchen said: Well there are almost no studies that tell us what types of antidepressant are best combined with CBT. We all know that adding CBT on top of drug treatment is beneficial and might produce better and more stable results in the long run.
We asked: There are a number of tests designed to measure domains of cognitive function in depression – can you provide guidance on which tests to use?
Dr Harrison said: There are lots of domains of cognition we could look at – episodic memory, working memory, attention. If I had just 10 minutes with a patient, I’d be tempted to use a version of the digit-symbol-substitution test, which tests lots of areas of cognition, so if there is a problem, it’s very likely to detect it. Another option would be to use working-memory tests. If these are computerised – I’d choose a one- or a two-back, while if the test needs to be paper-and-pencil based, I’d suggest digits-backwards. Then, I’d look at attention using a computerised test like choice-reaction-time.
Blowing hot and cold
We asked: How important is the distinction between hot and cold cognition when considering cognitive dysfunction in depression?
Prof Wittchen said: I think for clinicians the distinction between hot and cold cognitions is a useful reminder to explore the patient’s functioning in greater detail. Take the cold cognitions for example – such as attention, memory and concentration – these are necessary to maintain more complex cognitive structures such as making decisions, following-up plans and putting them into action. These cold cognitions are a prerequisite for the hot cognitions which actually involve emotion, affect and feelings as well.
Sensitive to criticism
We asked: To what extent is response to negative feedback state-related?
Prof Harmer said: Once a patient has received negative feedback on a task, or noticed that they have made an error, they then go on and make further errors in that task. And that seems to be something quite specific to depression. To some extent, this has been investigated only when depressed patients are currently ill, so we don’t know if it is state or trait-related. But some evidence suggests it may be trait-related in that it’s also seen in people that are at heightened risk of developing depression.
We asked: What is the impact of insomnia on cognitive function in depression, both during the acute phase and on the residual cognitive symptoms during remission?
Prof Wittchen said: Sleep and the quality of sleep has a tremendous effect on cognition – how you can memorise, work, concentrate and function. And particularly in a depressive episode – sleep disturbances heavily affect cognitive function. So it’s important to address sleep disturbance as well as cognitive function.
Who we spoke to:
Professor Hans-Ulrich Wittchen, Chair of the Institute of Clinical Psychology and Psychotherapy at the Technische Universitat, Dresden, Germany.
Dr John Harrison, Honorary Senior Lecturer at the Department of Medicine, Imperial College London, UK.
Professor Catherine Harmer, Professor of Cognitive Neuroscience in the Department of Psychiatry, Oxford University, UK.
Want more of the same?
More from these experts – all of whom are members of the THINC Task Force – can be found at www.THINCcognition.com