Bipolar Disorder – Mind the Gap Blog

Genetics of dopamine and serotonin explain overlap in psychiatric disorders

Posted on January 20, 2022 by jcabanadominguez

Psychiatric disorders such as attention deficit / hyperactivity disorder (ADHD), autism, major depression or bipolar disorder, often overlap and occur together. For example, individuals with ADHD on average experience twice as many depressive symptoms as the general population without ADHD [1,2]. In addition to the distress and impairment that is brought on by a single psychiatric condition, having multiple conditions can hugely increase the severity of symptoms and hinder treatment. To better understand why these disorders overlap, we investigated the genetic risk factors that are shared among psychiatric disorders, and found several genes that play important roles in regulating two signaling-mechanisms of the brain: dopamine and serotonin [3].

Dopamine and serotonin are two important neurotransmitters (messengers molecules that transmit messages between brain cells) that control a wide range of essential functions in your brain (e.g. controlling your movements, cognition, motivation, regulation of emotions, and responding to reinforcement and reward). For that reason, alterations in these two systems have been related with the physiopathology of several psychiatric disorders, and also have been pointed as possible therapeutic targets for them.

We systematically explored the contribution of common variants in genes involved in dopaminergic and serotonergic neurotransmission in eight psychiatric disorders (ADHD, anorexia nervosa, autism spectrum disorder , bipolar disorder, depression, obsessive-compulsive disorder, schizophrenia and Tourette’s syndrome) studied individually and in combination. To do so, we used data from the Psychiatric Genomics Consortium (PGC, https://www.med.unc.edu/pgc/) to explore the entire genome in thousands of patients with different psychiatric conditions, which were compared with controls (individuals without any psychiatric condition).

In this way, we could identify variations in genes (and in groups of related genes) that confer susceptibility to a given disorder. For example, a gene named CACNA1C that is involved in the connectivity between brain cells, was found to contribute to both bipolar disorder and schizophrenia. Using this approach, we found 67 dopaminergic and/or serotonergic genes associated with at least one of the eight studied disorders, and twelve of them were associated with two conditions. Interestingly, five out of these twelve genes, including CACNA1C, belong to both the dopaminergic and serotonergic neurotransmitter systems, highlighting the importance of those genes that participate in both systems and their high interconnectivity. Next, we analyzed groups of genes that work together, and found that the dopaminergic genes have an important role in ADHD, autism, depression, and in the combination of all of the eight disorders that we studied. We also found that the group of serotonergic genes are relevant for the overlap between depression and bipolar disorder.

These results support the existence of a set of dopaminergic and serotonergic genes that increase the risk of having multiple psychiatric conditions. Having identified these genes, the next step is to investigate if any of these could be targeted by new drugs that directly influence specific parts of the dopaminergic or serotonergic system, compared to the more unspecific drugs that currently exist. That would be an important step for treating psychiatric comorbidity.

If you want to know more about this research, you can read our publication here.

This blog was written by dr. Judit Cabana-Domínguez. She is a postdoctoral researcher of psychiatric genomics at the Vall d’Hebron Research Institute (VHIR). The work described here is part of the CoCA project on comorbid conditions of ADHD.

References

McIntosch et al. (2009). Adult ADHD and comorbid depression: A consensus-derived diagnostic algorithm for ADHD (nih.gov) Neuropsychiatric Disease and Treatment, 5: 137-150. doi: 10.2147/ndt.s4720
Di Trani et al. (2014). Comorbid Depressive Disorders in ADHD: The Role of ADHD Severity, Subtypes and Familial Psychiatric Disorders (nih.gov) Psychiatry Investigation, 11(2): 137-142. doi: 10.4306/pi.2014.11.2.137
Cabana-Domínguez et al. (2022). Comprehensive exploration of the genetic contribution of the dopaminergic and serotonergic pathways to psychiatric disorders. Translational Psyciatry, 12(1): 11. doi: 10.1038/s41398-021-01771-3

IS GENETICS BEHIND THE CO-OCCURRENCE OF ADHD AND OTHER DISORDERS?

Posted on May 10, 2021May 12, 2021 by Bru Cormand

A group of researchers from Spain, The Netherlands, Germany, Estonia, Denmark and USA have joined efforts to gain insight into the genetics of ADHD and its comorbidities. This ambitious objective was addressed by the Work Package 2 of a big project called CoCA: “Comorbid Conditions of Attention deficit/hyperactivity disorder (ADHD)”, funded by the European Union for the period 2016-2021.

In psychiatry, the co-occurrence of different conditions in the same individual (or comorbidity) is the rule rather than the exception. This is particularly true for ADHD, where conditions like major depressive disorder or substance use disorders frequently add to the primary diagnosis and lead to a worse trajectory across the lifespan.

There are different reasons that may explain the advent of the comorbidities: Sometimes the two conditions have independent origins but coincide in a single patient. Comorbidity can also appear as a consequence of a feature of a primary disorder that leads to a secondary disorder. For example, impulsivity, a trait that is common in ADHD, can be an entry point to substance use. Comorbidity can also be the result of shared genetic causes. The latter has been the focus of our investigations and it involves certain risk genes that act on different pathologies, a phenomenon called pleiotropy.

Our project started with an approach based on the exploration of candidate genes, particularly those involved in neurotransmission (i.e. the connectivity between neurons) and also in the regulation of the circadian rhythm. We used genetic data of more than 160,000 patients with any of eight psychiatric disorders, including ADHD, and identified a set of neurotransmission genes that are involved at the same time in ADHD and in autism spectrum disorder [1]. In another study we identified the same gene set as involved in obesity measures [2].

Then we opened our analyses to genome-wide approaches, i.e. to the interrogation of every single gene in the genome. To do that we used different statistical methods, including the estimation of the overall shared genetics between pairs of disorders (genetic correlation, r_g), the prediction of a condition based on the genetic risk factors for another condition (polygenic risk score analysis, PRS) and the establishment of the causal relationships between disorders (mendelian randomization). As a result, we encountered genetic connections between ADHD and several psychiatric disorders, like cannabis or cocaine use disorders [3, 4, 5], alcohol or smoking-related phenotypes [6, 7, 8], bipolar disorder [9], depression [6], disruptive behavior disorder [10], but also with personality or cognition traits, like neuroticism, risk taking, emotional lability, aggressive behavior or educational attainment [6 , 11, 12, 13], or with somatic conditions, such as obesity [11, 12].

All these results and others, reported in more than 40 (!) scientific publications, support our initial hypothesis that certain genetic factors cut across psychiatric disorders and explain, at least in part, the comorbidity that we observe between ADHD and many other conditions. This information can be very useful to anticipate possible clinical trajectories in ADHD patients, and hence prevent potential negative outcomes.

Dr. Bru Cormand is full professor of genetics and head of the department of Genetics, Microbiology & Statistics at the University of Barcelona. He leads workpackage 2 of the CoCA project (www.coca-project.eu) on the genetics of ADHD comorbidity.

References

Common mental health symptoms in ADHD

Posted on August 13, 2020August 13, 2020 by Jeanette Mostert

Image by Anastasia Gepp from Pixabay — Excessive, uncontrolled mind-wandering is common to ADHD, but also to other mental health conditions. Mobile apps that prompt questions during the day can give more insight into the nature of these symptoms and how they differ between (often comorbid) conditions.

The majority of individuals with ADHD have one or more comorbid disorders. Comorbidity is a technical (and admittedly, not very cheerful) word for ‘co-occuring’, meaning that multiple disorders or conditions are present at the same time. Anxiety and depression are the most prevalent conditions that co-occur with ADHD.

Researchers and clinicians want to better understand this comorbidity in ADHD. Does having ADHD increase your risk of developing other conditions? Is there a biolgical mechanism that underlies both ADHD and other conditions? Or are symptoms of ADHD actually broader than the attentional, hyperactivity and impulsivity problems defined by the DSM/ICD, and therefore also linked to other conditions? Or all of the above?

Going with the third option (which by no means excludes the alternatives), clinicians have noticed that many individuals with ADHD experience symptoms that are not specific to ADHD, but are also often seen in other psychiatric conditions. You could call these symptoms ‘mainstream’, or ‘common’ mental health problems. Some examples that are often experienced by those with ADHD are emotional instability, sleep problems, low self-esteem, distractibility and concentration problems, and mental restlesnesss or excessive mind wandering.

Understanding these comorbidities better is important, because often one condition can hide the ‘true’ underlying condition. For instance, a person with ADHD who experiences many symptoms that are also characteristic of anxiety (i.e. low self-esteem, excessive mind-wandering, sleep problems, avoiding difficult situations). In such a case, the person could receive treatment for anxiety problems, while he or she is actually needing treatment for ADHD.

To distinguish between these conditions better, we need to find out more about these common symptoms. Being distracted can have many different causes and can happen in many different situations. For instance: are you distracted due to pervasive negative thoughts, because the task you’re doing is boring, or because you’re thinking of many related things and drift off to new ideas?

To learn more about the nature of these symptoms, researchers have given mobile apps or smartwatches to participants with ADHD. Several times a day, the watch buzzes and the app prompts a question that the person has to give answer to immediately. Questions can for instance be: How are you feeling right now? Have good/bad things happend to you in the last hour? How much has this affectd you? Were you concentrating on a task or where you distracted? Where you tinking about something (un)pleasant? etc. This method called ‘experience sampling’ can give very valuable information about someone’s symptoms. When combining the information from a lot of individuals, this can also identify differences between different disorders, that were not really known before.

If you want to learn more about this topic, you can watch this webinar by professor Philip Asherson from King’s College London. He explains the common mental health symptoms of ADHD in more detail, and gives examples from his research, also using experience sampling.

This blog is based on the webinar by Philip Asherson “ADHD in the mainstream” that was created as part of the CoCA project. The CoCA project investigates comorbid conditons of ADHD: .

How psychiatric genetics can help to guide diagnostic practice and therapy

Posted on June 4, 2020 by Jeanette Mostert

Recently, professor Stephen Faraone from SUNY Upstate University in the USA gave a webinar about genetic research in psychiatry (especially ADHD) and how this can help to better understand diagnosis and provide better treatment. In this blog I will share with you some highlights from this webinar.

ADHD is a continuous trait in the population

ADHD is not something that you either have or don’t have. Rather, symptoms or characteristics of ADHD are present in the entire population, in varying severity. The system for psychiatric diagnoses is however based on categorical definitions that determine when a certain combination of symptoms and severity can be classified as a particular disorder. Although these categories can be of great help to provide public health data or determine insurance coverage, they often don’t really match individual cases. Hence there arise problems with heterogeneity, subtypes, subthreshold cases and comorbidity.

Genetic research has shown that psychiatric conditions such as ADHD are not caused by a few single genes, but rather by thousands or tens of thousands genetic variants that each contribute slightly to the ADHD risk. These so-called polygenic risk scores form a normal distribution across the entire population, with the majority of people having low polygenic risk scores (so a low to average risk of ADHD), while a small portion of individuals have a very low or very high risk. This adds to our understanding that ADHD is a continuous trait in the population.

*Image from the webinar by prof. Stephen Faraone*. *The higher the number on the x-axis, the higher the genetic risk of having ADHD. Negative numbers mean reduced genetic risk of ADHD.*

2. Comorbidity in psychiatry is the norm, rather than the exception

In the webinar, Stephen Faraone explains that in 90’s it was thought impossible that an individual can have both ADHD and depression. Now, we know better than that. There are substantial genetic correlations between different psychiatric disorders, meaning that the genes that increase the risk of for instance ADHD, also increase the risk of schizophrenia, depression, bipolar disorder, autism and tic disorder. This is further evidence that psychiatric conditions are not separate, categorial entities but rather arise from similar biological mechanisms.

3. Personalised medicine and pharmacogenetics are not yet sufficiently established to adopt widely and replace current medication on a broad scale

The second part of the webinar was about pharmacogenetic testing. This means that an individual’s genetic profile is used to determine whether a drug will be effective, and in what dose. Although this sounds promising, there is still a lot of discussion about the validity of such tests. This is due to varying results, differing protocols and large heterogeneity between studies. In some cases, pharmacogenetic testing can help to find the right treatment for an individual, for instance when this person is not responding well to regular treatment, but it is definitely not a fool-proof method yet. Better randomized controlled clinical trials are needed to improve reliability of these tests.

You can watch the full webinar here: https://www.youtube.com/watch?v=DLgqdJWZKIo

The genetics of having multiple mental health conditions

Posted on May 26, 2020May 26, 2020 by Jeanette Mostert

We know that psychiatric conditions have a strong genetic component. This means that genes play an important role in determining an individual’s risk or vulnerability to develop a psychiatric condition. However, there is evidence that there are genetic variants that increase the risk for multiple psychiatric disorders. This is called pleiotropy. Researchers of the “Cross-Disorder Group of the Psychiatric Genomics Consortium” have searched the entire genome of 727,000 individuals (of whom 233,000 were diagnosed with a psychiatric disorder) to identify genetic variants with such pleiotropy.

The researchers found one particular gene – called DCC – that increases vulnerability for all eight disorders that were investigated: ADHD, autism spectrum disorder, anorexia nervosa, bipolar disorder, major depression, obsessive compulsive disorder, schizophrenia and Tourette syndrome.

They also found more than 100 genetic variants that predispose to at least two psychiatric disorders, and around 20 variants that are associated with four or more. This means that the genes that contain these variants can be interesting to further understand why certain individuals are more vulnerable to develop psychiatric illnesses than others.

One of the researchers, professor Bru Cormand, explains more about this research in this blog.

Further reading: Cross-Disorder Group of the Psychiatric Genomics Consortium (2019): Genomic Relationships, Novel Loci, and Pleiotropic Mechanisms across Eight Psychiatric Disorders. Cell, 179(7): 1469-1482.e11.

Professor Cormand is involved in the CoCA research consortium where he investigates the genetic overlap between ADHD, major depression, anxiety disorder, substance use disorder and obesity. To read more about this, see for instance this other blog by him and dr. Judit Cabana Dominguez.

Food & mental health: the Eat2beNICE project

Posted on November 18, 2019 by Jeanette Mostert

We all know that a healthy lifestyle is beneficial for our health. But many of us forget that eating healthy, exercising regularly and getting enough sleep is also important for good mental health. In the Eat2beNICE research project a large team of researchers is investigating the link between food and mental health, specifically impulsivity, compulsivity and aggression. To share this knowledge with the rest of the world, they work together with food consultant Sebastian Lege.

The Eat2beNICE project just released a video to explain what the research is about and why it’s important. In this video Sebastian Lege visits the project coordinator Alejandro Arias-Vasquez, en several other researchers in the consortium.

More information about the Eat2beNICE project can be found at http://www.newbrainnutrition.com

Who is the average patient with ADHD?

Posted on March 6, 2019June 27, 2019 by thomaswolfers

Is there an ‘average ADHD brain’? Our research group (from the Radboudumc in Nijmegen) shows that the average patient with ADHD does not exist biologically. These findings were recently published in the journal. Psychological Medicine.

Most biological psychiatry research heavily relies on so-called case-control comparisons. In this approach a group of patients with for instance ADHD is compared against a group of healthy individuals on a number of biological variables. If significant group effects are observed those are related to for instance the diagnosis ADHD. This often results in statements such as individuals with ADHD show differences in certain brain structures. While our results are in line with those earlier detected group effects, we clearly show that a simple comparison of these effects disguises individual differences between patients with the same mental disorder.

Modelling individual brains

In order to show this, we developed a technique called ‘normative modelling’ which allows us to map the brain of each individual patient against typical development. In this way we can see that individual differences in brain structure across individuals with ADHD are far greater than previously anticipated. In future, we hope that this approach provides important insights and sound evidence for an individualized approach to mental healthcare for ADHD and other mental disorders.

Individual differences in ADHD

When we studied the brain scans of individual patients, the differences between those were substantial. Only a few identical abnormalities in the brain occurred in more than two percent of patients. Marquand: “The brains of individuals with ADHD deviate so much from the average that the average has little to say about what might be occurring in the brain of an individual.”

Personalized diagnosis of ADHD

The research shows that almost every patient with ADHD has her or his own biological profile. The current method of making a diagnosis of psychiatric disorders based on symptoms is therefore not sufficient, the authors say: “Variation between patients is reflected in the brain, but despite this enormous variation all these people get the same diagnosis. Thus, we cannot achieve a better understanding of the biology behind ADHD by studying the average patient. We need to understand for each individual what the causes of a disorder may be. Insights based on research at group level say little about the individual patient.”

Re-conceptualize mental disorders

The researchers want to make a fingerprint of individual brains on the basis of differences in relation to the healthy range. Wolfers: “Psychiatrists and psychologists know very well that each patient is an individual with her or his own tale, history and biology. Nevertheless, we use diagnostic models that largely ignore these differences. Here, we raise this issue by showing that the average patient has limited informative value and by including biological, symptomatic and demographic information into our models. In future we hope that this kinds of models will help us to re-conceptualize mental disorders such as ADHD.”

Further reading

Wolfers, T., Beckmann, C.F., Hoogman, M., Buitelaar, J.K., Franke, B., Marquand, A.F. (2019). Individual differences v. the average patient: mapping the heterogeneity in ADHD using normative models. Psychological Medicine, https://doi.org/10.1017/S0033291719000084 .

This blog was written by Thomas Wolfers and Andre Marquand from the Radboudumc and Donders Institute for Brain, Cognition and Behaviour in Nijmegen, The Netherlands. On 15 March 2019 Thomas Wolfers will defend his doctoral thesis entitled ‘Towards precision medicine in psychiatry’ at the Radboud university in Nijmegen. You can find his thesis at http://www.thomaswolfers.com

ADHD Is A Risk Factor For Type Two Diabetes And High Blood Pressure, As Well As Other Psychiatric Disorders

Posted on November 13, 2018June 27, 2019 by Prof. Stephen Faraone

All Swedish residents have their health records tracked through unique personal identity numbers. That makes it possible to identify psychiatric and medical disorders with great accuracy across an entire population, in this case encompassing more than five and a half million adults aged 18 to 64. A subgroup of more than 1.6 million persons between the ages of 50 and 64 enabled a separate examination of disorders in older adults.

Slightly over one percent of the entire population (about 61,000) were diagnosed with ADHD at some point as an adult. Individuals with ADHD were nine times as likely to suffer from depression as were adults not diagnosed with ADHD. They were also more than nine times as likely to suffer from anxiety or a substance use disorder, and twenty times as likely to be diagnosed with bipolar disorder. These findings are very consistent with reports from clinical samples in the USA and Europe.

Adults with ADHD also had elevated levels of metabolic disorders, being almost twice as likely to have high blood pressure, and more than twice as likely to have type 2 diabetes. Persons with ADHD but without psychiatric comorbidities were also almost twice as likely to have high blood pressure, and more than twice as likely to have type 2 diabetes.

Similar patterns were found in men and women with ADHD, although comorbid depression, bipolar disorder, and anxiety were moderately more prevalent in females than in males, whereas substance use disorder, type 2 diabetes, and hypertension were more prevalent in males than in females.

ADHD was less than a third as prevalent in the over-50 population as in the general adult population. Nevertheless, individuals in this older group with ADHD were twelve times as likely to suffer from depression, anxiety, or substance use disorders, and more than 23 times as likely to be diagnosed with bipolar disorder as their non-ADHD peers. They were also 63% more likely to have high blood pressure, and 72% more likely to have type 2 diabetes.

The authors noted, “Although the mechanisms underlying these associations are not well understood, we know from both epidemiologic and molecular genetic studies that a shared genetic predisposition might account for the coexistence of two or more psychiatric conditions. In addition, individuals with ADHD may experience increased difficulties as the demands of life increase, which may contribute to the development of depression and anxiety.” As for associations with hypertension and type 2 diabetes, these “might reflect health risk behaviors among adult patients with comorbid ADHD in addition to a shared biological substrate. As others have noted, inattention, disinhibition, and disorganization associated with ADHD could make it difficult for patients to adhere to treatment regimens for metabolic disorders.” They concluded that “Clinicians should remain vigilant for a wide range of psychiatric and metabolic problems in ADHD affected adults of all ages and both sexes.”

Stephen Faraone is distinguished Professor of Psychiatry and of Neuroscience and Physiology at SUNY Upstate Medical University and is working on the H2020-funded project CoCA.

REFERENCES

Qi Chen, Catharina A. Hartman, Jan Haavik, Jaanus Harro, Kari Klungsøyr, TorArne Hegvik, Rob Wanders, Cæcilie Ottosen, Søren Dalsgaard, Stephen V. Faraone, Henrik Larsson, “Common psychiatric and metabolic comorbidity of adult attention-deficit/hyperactivity disorder: A population-based cross-sectional study,” PLoS ONE (2018), 13(9): e0204516. https://doi.org/10.1371/journal.pone.0204516.

New England Journal of Medicine – Journal Watch Psychiatry Top Stories of 2016 – ADHD is a hot topic!

Posted on December 31, 2016January 13, 2017 by nitricx

firework Now that the year is coming to an end, we are flooded with reviews of the year. For many reasons, 2016 wasn’t a particularly good year: especially some “democratic” decisions made this year cast some doubt on the so-called “swarm intelligence” which in 2016 apparently turned into “swarm dullness”. With alt-right, fake news and the post-factual world being an imminent threat to mental sanity, we can only hope for a better 2017. Anyway – that’s not the topic of this blog post. As many other journals did, the top journal of the Medical World, NEJM has nominated their top articles in each speciality (http://www.jwatch.org/na43004/2016/12/23/nejm-journal-watch-psychiatry-top-stories-2016).

Amazingly, amongst the Top 10 papers in psychiatry, three dealt with ADHD – and even better, two of them featured IMpACT / MiND / Aggressotype / CoCA researchers in the author list! The papers are in detail:

the finding that the use of stimulants is safe in bipolar disorder with comorbid ADHD (Viktorin et al.; http://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2016.16040467 – also one of my favourite studies this year)(with H. Larsson, IMpACT / MiND / CoCA)
a meta-analysis showing that EEG-based neurofeedback does not have a significant beneficial effect in ADHD, and also suggesting that unblinding of the rater might have influenced positive reports (http://www.jaacap.com/article/S0890-8567(16)30095-8/abstract)(with Dani Brandeis, Aggressotype)
the equally sad as important report that young children (aged 5 to 11), who died by suicide, had more frequently symptoms of ADHD, rather than depressive features (almost 60% of 87 children). Also for this most devastating outcome, it is thus very important to adequately diagnose ADHD (http://pediatrics.aappublications.org/content/138/4/e20160436) especially considering that ADHD goes along with an increased risk for suicide life-long which can be lowered by MPH treatment.

In my opinion, the fact that the editors picked three ADHD-relevant papers for their top 10 list demonstrates that ADHD is a hot topic and that we provide cutting edge research in the field – and we will continue to do so in 2017! Watch out at this space for more news on ADHD / ASD, my personal top picks in 2016 and more exciting research in the coming year! Merry New Year and all the best for 2017 for all of you, may it bring peace, happiness and reason to this discomposed world.

How can we make sense of comorbidity?

Posted on August 10, 2016August 10, 2016 by janhaavik

Comorbidity, defined as the simultaneous occurrence of more than one disorder in a single patient, is commonplace in psychiatry and somatic medicine. In research, as well as in routine clinical settings.

In March 2016 the new H2020 collaborative project “CoCA” (Comorbidity in adult ADHD) was officially launched, with a 3-day kick-off meeting in Frankfurt, Germany. This ambitious project, which is coordinated by professor Andreas Reif and is co-maintaining this shared blog, will investigate multiple aspects of comorbidity in ADHD.

For instance, CoCA will “identify and validate mechanisms common to the most frequent psychiatric conditions, specifically ADHD, mood and anxiety disorders, and substance use disorders (SUD), as well as a highly prevalent somatic disorder, i.e. obesity”.

As reflected in this bold mission, most scientists trained in the biological sciences agree that studies of overlapping and concurrent phenomena may reveal some underlying common mechanisms, e.g. shared genetic or environmental risk factors.

However, particularly in psychiatry and psychology, the origins of comorbidity have been fiercely debated. Critics have argued that observed comorbidities are “artefacts” of the current diagnostic systems (Maj, Br J Psychiatry, 2005 186: 182–184).

This discussion relates to fundamental questions of how much of our scientific knowledge reflects an independent reality, or is merely a product of our own epistemological traditions. In psychiatry, the DSM and ICD classification systems have been accused of actively producing psychiatric phenomena, including artificial diagnoses and high comorbidity rates, rather than being “true” representations of underlying phenomena. Thus, the “constructivist” tradition argues that diagnostic systems are projected onto the phenomena of psychiatry, while “realists” acknowledge the presence of an independent reality of psychiatric disorders.

In an attempt to explain these concepts and their implications, psychiatric diagnoses and terminology have been termed “systems of convenience”, rather than phenomena that can be shown to be true or false per se (van Loo and Romeijn, Theor Med Bioeth. 2015, 41-60). It remains to be seen whether such philosophical clarifications will advance the ongoing debate related to the nature of medical diagnoses and their co-occurrence.

CoCA will not resolve these controversies. Neither can we expect that our new data will convince proponents of such opposing perspectives.

It is important to acknowledge the imperfections and limitations of concepts and instruments used in (psychiatric) research.

However, it may provide some comfort that similar fundamental discussions have a long tradition in other scientific disciplines, such as physics and mathematics. Rather than being portrayed as a weakness or peculiarity of psychiatric research, I consider that an active debate, with questioning and criticism is considered an essential part of a healthy scientific culture.

Hereby, you are invited to join this debate on this blog page! Wooden ruler vector