Who is the average patient with ADHD?

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

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!

fireworkNow 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?

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