Hello, I’m Dr Jonathan Bull a Research Scientist and member of the Steering Committee of The Collaborative Library, and this is a lay summary of an article called: The association between persistent cognitive difficulties and depression and functional outcomes in people with major depressive disorder. It was published in December 2022 in the journal of Psychological Medicine. So, why was this piece of research done? Well, according to the authors we don’t know much about how well people can think and how long such functional difficulties may last when someone is clinically depressed. And by how well they can think, we mean difficulty with organisation, with concentration and forgetfulness, and the impact that it has on there on their lives. How well does their memory work? How fast can they think? And how good is their attention? And could these added difficulties make them feel worse than they already do? Could it reduce their quality of life besides the depression itself? What did the researchers do in this article? They looked again at the results of a previous study, which they’d done on 623 people with Major Depressive Disorder (or MDD), or rather Recurrent Major Depressive Disorder. It was an app-based study gathering data on their depression, cognitive function, functional disability, which means how their lives are affected by their state of mind, and their self-esteem. And they followed them for two years during, which the subjects were self-reporting data in the app. And the research question is: Are persistent cognitive difficulties related to levels of depression and functional impairment during follow-up? So, in this subsequent study out of the 623 people they took 508, of which 76%, or just over three quarters, were women and the the population had an average age of 47. In brief, the answer to the question is ‘Yes!’ greater persistence that is longer lasting cognitive difficulties are associated with greater depression and functional impairment. They compared two groups, those with lower persistence of symptoms versus those with higher persistence and they found that there was a significant difference between the two groups. Those with higher persistence of symptoms had a higher level of depression. To summarise these results, they’re actually the same as the results of their previous study but with the additional insight that cognitive difficulties are associated with functional difficulties. So to put that in simple language, functional difficulties means social difficulties, absenteeism at work, low quality of life, and a reduced chance of recovery from depression. What they’re actually saying is that clinical depression is associated with other mental difficulties, including difficulties with organisation, concentration and forgetfulness, and that those have an impact on their quality of life and on their ability to carry on with normal work and social engagements. So, this has an impact for the patient. And what do I mean by ‘impact’, well according to the study a minority, or 38% of psychiatrists said that they used these other cognitive difficulties to monitor their patients with Major Depressive Disorder. So, that means that if they’re not monitoring these other symptoms, then they could still be persisting even if the psychiatrist thinks that the patient is getting better. So, that could lead to mis-informed treatment decisions being made. Alright, so that’s a quick summary of why they did it, what they did and what they found. Now going into some more details about the study itself, why did they do an app-based study? And by the way, the app is called THINC-it®. So, according to the authors, a laboratory setting, which is traditional for this kind of work is a costly and not a very natural way of getting real-world results. You get results in a clinical setting that may not reflect the patient’s real life.
Furthermore, the laboratory is not a good place for, or it’s not a practical place I should say, for measuring persistent effects because the patient has to return again and again. Alright, so that’s a good reason for doing an app-based study because a patient can do it in their own time, in their own home, and they don’t feel as much like they’re in front of a doctor. Now what are the downsides of this kind of study? Well, self-reporting your own cognitive function can be biased towards the optimistic, which is an unrealistic result. Or it may tend towards the pessimistic, but anyway self-reported is always subject to a little bit of error from personal judgment. But this paper aims to also test objective measures through the app by getting the subjects to do various tests to measure their attention, their working memory, their mental processing speed, so how fast they can think, and also their attention switching. So, these are all what we call measures of ‘cognitive function’ and can lead to a measurement of cognitive difficulties that patients are suffering. And then of course they also measured the depression symptoms themselves, through a standard questionnaire. Then the functional difficulties, which is if you like the impact on their everyday lives, that covered by questions about how well they’re coping at work, time management, running their home their the social leisure time, private leisure time, their personal and family relationships
Going into some more detail on the results: The one thing that was most associated with worse functioning at work than in private leisure time was so-called ‘attentional difficulties’, that is how well they can pay attention to things without losing focus. Another result was that working memory difficulties, in other words forgetfulness, was associated with worse functioning in all areas of life that were measured. And then a third result was that mental processing speed and executive function, so you can think of this as how fast and and effectively you’re able to think, it was found to be associated with worse function in all areas of life as well.
And so the authors concluded from these results that these are important things to capture with somebody who has an MDD, and the standard MDD questionnaires are missing questions on cognitive difficulties. And therefore they’re not getting the whole picture of the patient’s mental well-being. So, the authors conclude by recommending that more things should be measured when assessing patients with MDD to make sure that they are being treated effectively. Finally, every good study should end with a note on the limitations, which is how far you can take these conclusions and apply them in other settings. So, they noted that there wasn’t enough good data completeness, so in other words some people were not filling in everything or may not have been fully engaged with the app. And of course some people who are more engaged may have different symptoms to those who are less engaged, so there could be some inherent bias that weakens the result. Then the other thing is they’ve stated that there’s association between these cognitive difficulties and functional difficulties and depression, but this isn’t a causal effect. They’re not saying that depression causes other cognitive difficulties, and that these cause functional difficulties in their life, or the other way around. In fact it’s probably some kind of mixture of both directions.
And the final limitation of the study is this is a fairly small group sizes, so there’s a risk of not finding a so-called statistically significant result, which means that there’s a relatively low power to to make wider conclusions. But all that said and done this study fills a hole in the research literature and I think has some merit to his conclusions. Thank you for listening.
Image: “Depression” by Eddi van W. is licensed under CC BY-ND 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-nd/2.0/?ref=openverse.
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|Measuring Depression with an app: Audio lay summary
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|Dr Anja Harrison
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F. Matcham, S. Simblett, D. Leightley, M. Dalby, S. Siddi, J. Haro, F. Lamers, B. W. H. J. Penninx, ..., T. Wykes
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JCB and PA are full-time employees of H. Lundbeck A/S. VN is an employee of Janssen Research and Development, LLC and holds company stocks/stock options. JMH has received economic compensation for participating in advisory boards or giving educational lectures from Eli Lilly & Co, Sanofi, Lundbeck, and Otsuka. CO is supported by the UK Medical Research Council (MR/N013700/1) and King’s College London member of the MRC Doctoral Training Partnership in Biomedical Sciences. No other authors have competing interests to declare.
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