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New paper: “What are psychological constructs?”

One of the fundamental shortcomings of the empirical psychological literature on mental disorders, personality aspects, intelligence, or emotions is that there is a lack of depth regarding the discussion what these psychological constructs are. Researchers often use statistical models such as factor models and find 3 depression factors or 5 personality factors, but it remains entirely unclear what these factors represent. I have written about this in more detail here regarding the psychopathology literature for which this challenge is especially severe.

I was asked recently by the Editor of Health Psychology Review to write a commentary on a paper by Peters & Crutzen entitled “Pragmatic Nihilism: How a Theory of Nothing can Help Health Psychology Progress” (URL). While the paper covers a few interesting ideas, it was somewhat consistent with the majority of the psychological literature in ignoring prior discussion on what psychological constructs are. Continue reading

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New paper on stability and accuracy of psychological networks

Our paper “Estimating psychological networks and their accuracy: a tutorial paper” was published in Behavioral Research Methods as open access paper! You can find the full paper here, and the supplementary materials here.

In this paper, we raise the possible danger of an upcoming replicability crisis consistent with the rest of psychology, given that we are using highly data-driven network models, and provide you with opportunities to investigate the stability of your network analysis results in more detail. Continue reading

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Treatment-resistant depression: clarifications and important steps forward

I wrote this commentary together with Adam Chekroud. You can find a PDF version of this commentary here.


The largest and longest investigation of treatment-resistant depression (TRD) to date, the Sequenced Treatment Alternatives to Relieve Depression (STAR*D), was conducted in four stages. Each stage comprised a different medication, and patients moved to the next stage if they did not improve considerably. Only 25% of all depressed patients remitted in stage I, only 46% after all stages [1]. TRD is a common and severe mental health issue, and research has shown that it is associated with worse outcomes and predicts lack of future treatment response: only 1 in 10 patients respond to standard treatments within 1 year [2].

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New paper: the 52 symptoms of major depression

I published a new paper in the Journal of Affective Disorders entitled “The 52 symptoms of major depression: Lack of content overlap among seven common depression scales” (PDF).

The paper examines content overlap of 7 common depression scales, and concludes that the scales feature 52 distinct depression symptoms that are listed in the main Figure below.


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New paper on responsiveness of depression rating scales

After reviewing the paper “The relative responsiveness of test instruments can be estimated using a meta-analytic approach: an illustration with treatments for depression” by Kounali et al. 2016, the editor invited me to write a response because I raised the point that a large amount of researchers seem to misunderstand the concept of scale responsiveness.

In my paper entitled “Are more responsive depression scales really superior depression scales?” published in the Journal of Clinical Epidemiology (PDF), I clarify problems with contemporary work on responsiveness pertaining to content validity, longitudinal measurement invariance, and unidimensionality.

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New commentary on problems with latent class analysis in depression research

We have a new commentary in Molecular Psychiatry entitled “Problems with latent class analysis to detect data-driven subtypes of depression” (PDF; together with the fantastic Hanna van Loo, Rob Wanders & Klaas Wardenaar).

This was a response to numerous papers over the last years that found separate latent classes in depression that may be statistical artifacts and driven by violations of local independence.


» van Loo, H. M., Wanders, R. B. K., Wardenaar, K. J., & Fried, E. I. (2016). Problems with latent class analysis to detect data-driven subtypes of depression. Molecular Psychiatry. (PDF)

New network paper on comorbidity between mood and anxiety disorders

We have a new network paper out in Psychological Medicine entitled “Network Analysis of Depression and Anxiety Symptom Relations in a Psychiatric Sample” (PDF).

I tend to think of the paper as a state-of-the-art replication of the great comorbidity paper by Cramer et al. 2010 who investigated the comorbidity of depression and generalized anxiety disorder.

In contrast to Cramer et al. who analyzed data of mostly healthy participants, this paper (first-authored by Courtney Beard and Alex Millner ) estimated the network structure of depression and anxiety symptoms in a large clinical population, using regularized partial correlation networks. We also investigated the change of network structure over the course of an 8-day period.


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Call for papers on PTSD symptomics

I am very happy to announce that Cherie Armour and me are organizing a special issue for the European Journal of Psychotraumatology, together with the editor-in-chief Miranda Olff.


In summary, we are looking for papers on:

  • PTSD symptom networks, either on the level of groups or individuals, in cross-sectional or time-series data
  • The stability of PTSD symptomatology and PTSD networks over time
  • PTSD comorbidity research from a network perspective
  • Symptom-based analyses that investigate whether PTSD symptoms are differentially related to various clinically relevant variables such as impairment, risk factors, biomarkers, etc.
  • Systematic reviews focusing on PTSD symptomics

The deadline is December 20th; more infos are available here.

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Ketamin as promising treatment for suicidal thoughts?

Imagine you are a group of scientists and want to find out whether a novel drug X works on a specific problem Y. You run the following study:

  • You enroll a small sample of 14 participants who have the problem Y.
  • You give these 14 participants your novel drug, but you do not enroll a second group who received placebo medication, which means that any effect you find may be due to the placebo effect.
  • On top of that, all your 14 patients keep using a well-accepted medication for problem Y while taking the novel drug X, meaning that any changes you find may be due to their normal medication, not X.
  • You measure improvements of problem Y 240 minutes and 3 months after the treatment.
  • You find evidence of improvements for 7 of 14 people 240 minutes after treatment, and for 2 of 14 people 3 months later; it is unclear whether this is due to placebo, normal medication, or other reasons.
  • You write a scientific paper with the strong conclusion: “repeated doses of X rapidly and robustly decreased Y.”

This is exactly what what Ionescu et al. (2016) did in a new study entitled “Rapid and Sustained Reductions in Current Suicidal Ideation Following Repeated Doses of Intravenous Ketamine: Secondary Analysis of an Open-Label Study”, published in the Journal of Clinical Psychiatry. Continue reading


Adjunctive Nutraceuticals as depression treatment

(Series: critical commentaries on depression trials. Prior posts: 1, 2, 3, 4)

Antidepressants only marginally outperform placebos (Khan & Brown, 2015) – which has led to a number of novel strategies to try to improve treatment for patients suffering from depressive disorders. Adjunctive Nutraceuticals present one such strategy: providing patients with specific forms of dietary supplements in addition to antidepressants (Wikipedia: Nutraceuticals). This is in line with general dietary supplements: the industry has grown considerably in the last decades, and more than half of the US adult population consume dietary supplements regularly (Wikipedia: Dietary Supplements). Interestingly, meta-analyses have repeatedly failed to find any evidence for positive effects of dietary supplements such as Vitamin C on numerous health outcomes – ranging from the common cold to cancer – in general population samples (Hemilä & Chalker, 2013; Lee, Oh & Myung, 2015).

In a new paper entitled “Adjunctive Nutraceuticals for Depression: A Systematic Review and Meta-Analyses”, Sarris et al. investigated whether adjunctive nutraceuticals provide significant benefits to patients with Major Depression. They reviewed 40 studies in total: 9 studies on folic acid, folinic acid, methylfolate, or a combination of folic acid and vitamins B6 and B12; 8 on tryptophan (or 5-HTP) and omega-3; 4 on S-adenosylmethionine; 2 on zinc, inositol, vitamin C, and vitamin D; and 1 for creatine, B12, and an amino acid combination. The mean sample size per study was small (n=63), and only 31 of the 40 studies were randomized placebo-controlled trials.

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Hyperthermia as depression treatment

A few months back, a study was published in JAMA Psychiatry claiming that whole-body hyperthermia is an effective treatment for depression (UPDATE: the paper was published in full now on August 6th 2016, some time after the online first print). For those who don’t know psychiatric journals very well, JAMA Psychiatry is currently ranked highest psychiatric journal in terms of impact-factor.

I never got around to submit the commentary I wrote, but was interviewed a few days ago about the study by Eric Boodman, so I will briefly explain the main issues with the trial.

Due to the comparably low efficacy of classic antidepressant [1–3], psychiatry has recently looked for different avenues to depression treatment. One example is Ketamin [4], although the findings so far are very weak. Another example is a novel drug aimed to selectively influence the hippocampal volume of patients [5] (I previously wrote about this study here) – although hippocampal abnormalities are negligible in patients with Major Depression [6].

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Adjunctive Brexpiprazole as depression treatment?

Dr. Fava and colleagues have published an antidepressant trial on adjunctive Brexpiprazole, a novel atypical antipsychotic drug that was developed to treat schizophrenia, in the Journal of Clinical Psychiatry.

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The trial consisted of 4 steps:

  • The authors carefully selected 50 patients who had not shown improvements with their current antidepressant.
  • These patients received 2 more weeks of treatment with their current antidepressant, to provide a baseline measure.
  • For the next 6 weeks, patients additionally received Brexpiprazole, with a dosage from 1mg in week 1, 2mg in week 2, and 3mg in subsequent weeks.
  • Finally, patients received 4 more weeks of antidepressant treatment without Brexpiprazole.

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Is Seasonal Affective Disorder really just a “Folk Construct”?

Unpublished commentary. PDF, DOI 10.13140/RG.2.1.5149.7362.

Eiko I. Fried, University of Leuven, Belgium
Lauren M. Bylsma, University of Pittsburgh, USA
Randolph M. Nesse, Arizona State University, USA

After submitting the commentary to Clinical Psych Science, the Editor wrote us that they generally do not publish commentaries, despite the website stating they do. Unfortunate … we’ll just publish it here.

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Common problems of factors models in psychopathology research

I recently stumbled across the paper “A metastructural model of mental disorders and pathological personality traits”, authored by Aidan Wright and Leonard Simms in 2015. I enjoyed reading it: it’s a strong methodological paper, using state-of-the-art exploratory structural equation models (ESEM). It would have been a pleasure for me to review this paper: a very clear recommendation to publish.

However, the paper contains a few (what I personally consider to be) issues representative of the psychopathology structural equation modeling (SEM) literature in general. Therefore, I will use it as an example to write a more general critique. I’ll try to use non-technical language so that readers who know neither SEM nor psychopathology research well can follow.

It’s also very important to me to not misunderstand this as criticism of the authors. I very much like their work – in fact, we’re speaking in the same symposium at a conference later this year – it could really be any other paper as well.

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