Why 12 genetic markers for ADHD are exciting news for New Brain Nutrition

We are finally here: for the first time, genome-wide significant markers are identified that increase the risk for Attention Deficit / Hyperactivity Disorder (ADHD). This research was conducted by an international consortium of more than 200 experts on genetics and ADHD, and includes several researchers that are also involved in our Eat2beNICE project (the scientific basis of this New Brain Nutrition website). The findings were recently published in the prestigious journal “Nature Genetics” and will greatly advance the field of ADHD genetics research.

Why is this finding so important?

The genetics of ADHD are very complex. While ADHD is highly heritable, there are likely to be thousands of genes that contribute to the disorder. Each variant individually increases the risk by only a tiny fraction. To discover these variants, you therefore need incredibly large samples. Only then can you determine which variants are linked to ADHD. The now published study by Ditte Demontis and her team combined data from many different databases and studies, together including more than 55,000 individuals of whom over 22,000 had an ADHD diagnosis.

We can now be certain that the twelve genetic markers contribute to the risk of developing ADHD. Their influence is however very small, so these markers by themselves can’t tell if someone will have ADHD. What’s interesting for the researchers is that none of these markers were identified before in much smaller genetic studies of ADHD. So this provides many new research questions to further investigate the biological mechanisms of ADHD. For instance, several of the markers point to genes that are involved in brain development and neuronal communication.

Why are our researchers excited about this?

A second important finding from the study is that the genetic variants were not specific to ADHD, but overlapped with risk of lower education, higher risk of obesity, increased BMI, and type-2 diabetes. If genetic variants increase both your risk for mental health problems such as ADHD, and for nutrition-related problems such as obesity and type-2 diabetes, then there could be a shared biological mechanism that ties this all together.

We think that this mechanism is located in the communication between the gut and the brain. A complex combination of genetic and environmental factors influence this brain-gut communication, which leads to differences in behaviour, metabolism and (mental) health.genetic markers for adhd

The microorganisms in your gut play an important role in the interaction between your genes and outside environmental influences (such as stress, illness or your diet). Now that we know which genes are important in ADHD, we can investigate how their functioning is influenced by environmental factors. For instance, gut microorganisms can produce certain metabolites that interact with these genes.

The publication by Ditte Demontis and her co-workers is therefore not only relevant for the field of ADHD genetics, but brings us one step closer to understanding the biological factors that influence our mental health and wellbeing.

Further Reading

Demontis et al. (2018) Discovery of the first genome-wide significant risk loci for attention deficit/hyperactivity disorder. Nature Genetics. https://www.nature.com/articles/s41588-018-0269-7

The first author of the paper, Ditte Demontis, also wrote a blog about the publication. You can read it here: https://mind-the-gap.live/2018/12/10/the-first-risk-genes-for-adhd-has-been-identified/

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ADHD and Exercise

ADHD is among the most common psychiatric disorders, with ~3% prevalence in adulthood and ~5% in childhood. ADHD has a high risk for comorbid conditions. Comorbid means that one psychiatric disorder often comes together with another psychiatric disorder. For instance mood, anxiety and substance use disorders have high comorbid rates in adults with ADHD.

Adults with ADHD are also at risk for obesity and major depressive disorders and adolescent ADHD predicts adult obesity: 40% of adults with ADHD are also obese. These are worrying numbers. Many adults who have ADHD suffer from these negative consequences that come with their mental illness.

There is a growing body of scientific evidence of the powerful effects of nutrition and lifestyle on mental health. Exercise is one of them.It helps prevent or manage a wide range of health problems and concerns, including stroke, obesity, metabolic syndrome, type 2 diabetes, depression, a number of types of cancer and arthritis. Besides that, regular exercise can help you sleep better, reduce stress, sharpen your mental functioning, and improve your sex life. Nearly all studies revolve around aerobic exercise which includes walking, jogging, swimming, and cycling.

Recent research shows that exercise might also have a positive effect on ADHD symptoms such as improving attention and cognition1,2 Additional research is needed to explore this effect further, but we can take a look at the mechanisms underlying this effect.

One of the parts in our brain that is affected by exercise is the prefrontal cortex. The prefrontal cortex plays an important role in controlling impulsive behavior and attention, and is positively influenced by exercise. Furthermore, dopamine and norepinephrine play an important role in attention regulation. Ritalin, among one of the most well-known medication for ADHD, also increases levels of dopamine.

When you exercise regularly, the basis levels of dopamine and norepinephrine rise, and even new dopamine receptors are created. These dopamine levels are also the reason why exercise therapy can be effective for people suffering from depression: low levels of dopamine are a predictor of depressive symptoms.

Taken together: people with ADHD are at risk for obesity and depression. Exercise has a positive influence on obesity, depression and ADHD. Wouldn’t it be great if we could treat people with ADHD with an exercise therapy?

The PROUD-study is currently studying the prevention of depressive symptoms, obesity and the improvement of general health in adolescents and young-adults with ADHD. PROUD establishes feasibility and effect sizes of two kinds of interventions: an aerobic exercise therapy and the effects of a bright light therapy.

Exercise and ADHDParticipants follow a 10 week exercise intervention in which they train three days a week: one day of only aerobic activities (20-40 min) and in two of these days, muscle-strengthening and aerobic activities (35 – 60 min). An app guides them through the exercises, and the intensity and duration of these exercises increase gradually. During a 24 week course changes in mood, condition, ADHD symptoms and body composition are measured.

I am really looking forward to the results of the effectiveness of this intervention in adolescents and adults with ADHD. It is great that this study tries to alter a lifestyle instead of temporarily symptom-reducing options. A healthy life is a happy life!

For more information about the PROUD-study see www.adhd-beweging-lichttherapie.nl (only in Dutch) or contact the researchers via proud@karakter.com. For more information about a healthy lifestyle and the positive effects on mental health, see our other blogs at https://newbrainnutrition.com/

 

References

  1. Kamp CF, Sperlich B, Holmberg HC (2014). Exercise reduces the symptoms of attention-deficit/hyperactivity disorder and improves social behaviour, motor skills, strength and neuropsychological parameters. Acta Paediatrica, 103, 709-714.

 

  1. Choi JW, Han DH, Kang KD, Jung HY, Renshaw, PF (2015). Aerobic exercise and attention deficit hyperactivity disorder: brain research. Med Sci Sports Exerc, 47, 33-39.
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Maladaptive or uncontrolled impulsivity and compulsivity lead to emotional and social maladjustment, e.g. addiction and crime, and underlie psychiatric disorders. Recently, alterations in microbiota composition have shown to have implications for brain and social behaviors as we have been explaining in our lasts blogs. The microbiota-gut-brain axis may be involved in this process but the mechanisms are not fully identified (1). The supplementation of probiotics can modulate the microbial community and now has been suspected to contribute to ameliorating symptoms of a psychiatric disease with possible influence on social behaviors (2). To date, no randomized controlled trial has been performed to establish feasibility and efficacy of this intervention targeting the reduction of impulsivity and compulsivity. This gave us the idea to perform a study to investigate the effects of supplementation with probiotics, working with adults with Attention Deficit Hyperactivity Disorder (ADHD) and Borderline Personality Disorder (BPD) which in most cases present high levels of impulsivity, compulsivity and aggression.

Probiotics for healthWe call our project PROBIA, which is an acronym of “PROBiotics for Impulsivity in Adults”. This study will be performed in three centers of Europe including, Goethe University in Frankfurt, Semmelweis University in Budapest and Vall d’Hebron Research Institute (VHIR) in Barcelona, the coordinator of the clinical trial. We are planning to start recruiting patients in January of 2019 and obtain the results in 2021. In our study, we will explore the effects of probiotics by measuring the change in ADHD or BPD symptoms, general psychopathology, health-related quality of life, neurocognitive function, nutritional intake, and physical fitness. The effect of the intervention on the microbiome, epigenetics, blood biomarkers, and health will be also explored by collecting blood, stool, and saliva samples.

We are looking forward to having the results of this amazing study in order to understand the mechanisms involved in the crosstalk between the intestinal microbiome and the brain. If improvement effects can be established in these patients, new cost-effective treatment will be available to this population.

 This was co-authored by Josep Antoni Ramos-Quiroga, MD PhD, psychiatrist and Head of Department of Psychiatry at Hospital Universitari Vall d’Hebron in Barcelona, Spain. He is also professor at Universitat Autònoma de Barcelona.

Sources

  1. Desbonnet L, Clarke G, Shanahan F, Dinan TG, Cryan JF. Microbiota is essential for social development in the mouse. Mol Psychiatry [Internet]. The Author(s); 2013 May 21;19:146. Available from: http://dx.doi.org/10.1038/mp.2013.65
  2. Felice VD, O SM. The microbiome and disorders of the central nervous system. 2017 [cited 2017 Oct 16]; Available from: https://ac.els-cdn.com/S0091305717300242/1-s2.0-S0091305717300242-main.pdf?_tid=b52750d8-b2ae-11e7-819b-00000aab0f02&acdnat=1508185089_58e99184d2c0f677d79ff1dd88d02667

 

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What is inflammation?

Inflammation is the response of the body’s immune system against external factors that can put your health in danger. When this system feels it is attacked by something that may harm your health, it activates some molecules that are called cytokines in order to neutralize or avoid any damage so you can be safe.

Why is inflammation bad? What does it do?

Inflammation isn’t bad by itself, since its purpose is to protect our body. In some cases however, when the duration of this response is extended for too long- I’m talking about years- it can cause harmful effects to your health. Especially, it can affect the brain by active transport of cytokines throughout this organ.

Neuro-inflammation may occur if this process continues past early stages. Neuro-inflammation plays an important role in the development of mental diseases such as attention-deficit/hyperactivity disorder (ADHD), autism, schizophrenia, depression, anxiety, bipolar disorder (BD), and obsessive-compulsive disorder (OCD), where elevated levels of inflammation have been found(1).

What causes inflammation? 

Inflammation can occur by different factors. Some of them could be: pathogens, injuries, chronic stress, and diseases like dermatitis, cystitis or bronchitis to mention a few.

Nutritional factors like overweight and poor diet quality can also trigger this process by increasing fat accumulation in our cells and damaging them (2). The exact mechanisms that are involved in these processes are still in research.

What decreases inflammation?

Research has found that adhering to a healthy diet, like the Mediterranean diet, characterized by high intake of fruit, vegetables, whole grains, fish, lean meats and nuts, can decrease inflammation and protect you against depressive symptoms and anxiety (3,4).

There is evidence that prebiotics, probiotics and synbiotics (a combination of prebiotics and probiotics) can also help lowering inflammation. In addition, you should avoid eating pro-inflammatory foods that have been found to increase the risk of inflammation, and with it mental disorders. Some of these are refined carbohydrates, beverages with a lot of sugar added like soda, juice and sports drinks, processed meat and foods high in saturated fats (5).

What are anti-inflammatory foods

Anti-inflammatory foods are the contrast of pro-inflammatory foods. These are foods that have been found to promote or induce low levels of inflammation in our body, which may protect us against neurological disorders. Briefly, these foods include fruits, vegetables, olive oil, fish and spices like curcuma (turmeric).

Here’s what YOU can do to minimize inflammation and improve your mental health.

Inflammation and Foods

This was co-authored by Josep Antoni Ramos-Quiroga, MD PhD psychiatrist and Head of Department of Psychiatry at Hospital Universitari Vall d’Hebron in Barcelona, Spain. He is also professor at Universitat Autònoma de Barcelona.

Sources

  1. Mitchell RHB, Goldstein BI. Inflammation in children and adolescents with neuropsychiatric disorders: A systematic review. J Am Acad Child Adolesc Psychiatry [Internet]. Elsevier Inc; 2014;53(3):274–96. Available from: http://dx.doi.org/10.1016/j.jaac.2013.11.013
  2. Ogłodek EA, Just MJ. The Association between Inflammatory Markers (iNOS, HO-1, IL-33, MIP-1β) and Depression with and without Posttraumatic Stress Disorder. Pharmacol Reports [Internet]. 2018;70:1065–72. Available from: https://www.sciencedirect.com/science/article/abs/pii/S1734114017305923
  3. Lassale C, Batty GD, Baghdadli A, Jacka F, Sánchez-Villegas A, Kivimäki M, et al. Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies. Mol Psychiatry [Internet]. Springer US; 2018;1. Available from: http://www.nature.com/articles/s41380-018-0237-8
  4. Phillips CM, Shivappa N, Hébert JR, Perry IJ. Dietary inflammatory index and mental health: A cross-sectional analysis of the relationship with depressive symptoms, anxiety and well-being in adults. Clin Nutr. 2017;37.
  5. Shivappa N, Bonaccio M, Hebert JR, Di Castelnuovo A, Costanzo S, Ruggiero E, et al. Association of proinflammatory diet with low-grade inflammation: results from the Moli-sani study. Nutrition. 2018;54:182–8.

 

 

 

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Shine a Light on ADHD

October is international ADHD Awareness month. Young researchers of the MiND research project and 4QuarterFilms just published this short documentary that shines a light on living with ADHD, from a personal and a scientific perspective.

Watch the video here: http://newbrainnutrition.com/adhd-shine-a-light/

We thank the following professionals who were interviewed in this video:
Dr. Barbara Franke and Dr. Corina Greven, of Donders Institute, Radboud University Medical Center
Dr. Philip Asherson, Dr. Eric Taylor, and Dr. Kai Syng Tan of King’s College London
Mrs. Andrea Bilbao of ADDISS, ADHD Europe
We also thank ms. Evie Travers, mr. Bryn Travers and mr. Aziz who were interviewed in this video.

Shine_a_Light_on_ADHDThe film was made possible with the help of the EU-funded programs:
MiND (EU horizon 2020 program no 643051) http://mind-project.eu/
Aggressotype (EU FP7 program No 602805) http://www.aggressotype.eu/
CoCA (EU horizon 2020 program No 667302) http://coca-project.eu/
Eat2beNICE (EU horizon 2020 program No 728018). http://newbrainnutrition.com/

 

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A team of Iranian researchers recently published a meta-analysis seeking to determine what, if any, association there may be between low Vitamin D levels and ADHD in children and adolescents.

Combining the results from thirteen studies with 10,334 participants, they found that youth with ADHD had “modest but significant” lower serum concentrations of 25-hydroxyvitamin D than normally developing children. The weighted mean difference was just under 7 nanograms per milliliter. The odds of obtaining such a result by chance would be less than one in a thousand (p < .001). There was little to no sign of publication bias. Between-study heterogeneity, however, was very high (I2 = 94).

Vitamin D and ADHDThese results suggest an association. But are low serum levels of Vitamin D a cause or effect of ADHD? Causation is vastly more difficult to establish than association. To begin to tease this out, the researchers identified four prospective studies that compared maternal Vitamin D levels with the subsequent development of ADHD symptoms in their children. Two of these used maternal serum levels, and two used umbilical cord serum levels. Together, these studies found that low maternal Vitamin D levels were associated with a 40% higher risk of ADHD in their children. Whether maternal serum or umbilical cord serum measurements were used had little or no effect on the outcome. Study heterogeneity was negligible. But the authors noted that this result “should be considered with caution” because it was heavily dependent on one of the prospective studies included in the analysis. All of which suggests a need for further prospective studies.

In the meantime, the authors suggest it would be prudent to increase sun exposure and Vitamin D supplementation given the prevalence of Vitamin D deficiency.

REFERENCES

Yadollah Khoshbakht, Reza Bidaki, and Amin Salehi-Abargouei, “Vitamin D Status and Attention Deficit Hyperactivity Disorder: A Systematic Review and Meta-Analysis of Observational Studies,” Advances in Nutrition, vol. 9, issue 1, p. 9-20 (2018).

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In studies about treatment for children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD), it is important to use valid and reliable instruments to measure effects. A valid instrument can measure a difference in symptoms before and some time after the treatment has started. Usually questionnaires for parents and teachers are used.

In the TRACE project, currently running in the Netherlands, we are looking at the effectiveness of a dietary intervention versus care as usual, for children diagnosed with ADHD in the age group of 5-12 year old. In addition to the standard questionnaires, there is an observation instrument called the Disruptive Behavior Diagnostic Observation Schedule (DB-DOS). This instrument was added in the TRACE project as an objective measurement for changes in behavior.

DB-DOS, ADHDThe DB-DOS was originally developed to measure disruptive behavior disorders (DBD) in preschoolers1. This way, treatment effects are not only measured in an indirect way, through information of caregivers, but also in a direct observation in the clinical setting. However, the age range of the children in the TRACE project is different from the preschoolers the DB-DOS was originally intented for. That’s why the TRACE project added several tasks to the original DB-DOS, to make sure it elicits disruptive behaviours, as well as hyperactivity and impulsivity, and to make it suitable for older children. During the current trial we try to find out if the DB-DOS is also a valid measurement for older children, aged 5-12 years.

The DB-DOS uses three different interactional contexts: parent-child context, examiner-child context and parent-examiner-child context. Children will be asked to complete different tasks. Some are rather boring, or frustrating, to see if this may elicit attention problems, hyperactivity, impulsive behaviour or disruptive behaviors. The DB-DOS contains, for example, some tasks which can evoke anger or sadness and some tasks where children get the chance to cheat. The reaction of the child is observed from behind a one-way screen. The observation lasts about 60 minutes and afterwards the observed behavior is scored by the examiner through a coding system. With more evidence-based instruments, mental health problems can be targeted more efficiently and reliably.

Our final goal is earlier interventions which prevent mental health problems in these children getting more severe and spreading through other domains such as school, work, or social contacts.

We will keep you posted about the results of the DB-DOS in the TRACE project!

REFERENCE
1 Bunte, T. L., Laschen, S., Schoemaker, K., Hessen, D. J., Van der Heijden, P. G. M., & Matthys, W. (2013). Clinical Usefulness of Observational Assessment in the Diagnosis of DBD and ADHD in Preschoolers. Journal of Clinical Child & Adolescent Psychology, 42(6), p.p. 749-761.
http://dx.doi.org/10.1080/15374416.2013.773516

 

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In every classroom approximately two children are diagnosed with Attention Deficit Hyperactivity Disorder (ADHD). They struggle with attention problems and hyperactive and impulsive behavior. This has negative consequences for these children. For example, they can have difficulties learning, it puts them at risk for other psychiatric problems, and it can cause parent-child relationship problems. Therefore, children with ADHD do need some sort of treatment for optimizing the quality of their lives.

After psycho-education to the child, parents and teacher, medication is often the first choice of treatment because it is evidence-based. However, there is a growing group of parents that do not wish to medicate their child. They are concerned about the side and long-term effects. Thus, these parents seek other treatment. That is where they get stuck: which other effective treatments are available?

In order to develop new treatments, there is a growing field of research focusing on risk factors for ADHD symptoms. One of these risk factors that has been studied increasingly is nutrition. Nutrition plays a role in physical well-being, but could also play a role in psychological well-being and cognitive functioning. Consequently, dietary treatments could be an alternative treatment for children with ADHD. There is a long history of research in nutrition, but there is not enough evidence yet about the (cost-)effectiveness to implement dietary treatments in clinical health care.

Elimination DietSo far, studies examining the effectiveness of a so-called elimination diet showed the strongest effects (1). The aim of an elimination diet is to find out which products trigger ADHD symptoms. However, results of these studies are inconclusive because of several limitations. First, outcome measurements used in these studies were not objective. Second, studies suffered from a sample bias towards highly motivated and educated parents. Third, underlying mechanisms are still unknown. Fourth, long-term effects are unknown. Moreover, it is unknown if an elimination diet is more effective in reducing ADHD symptoms than a healthy diet based on the World Health Organization (WHO) guidelines (2).

We thought: can we take into account these limitations and examine the effectiveness of two dietary treatments? This resulted in the TRACE study: ‘Treatment of ADHD with Care as usual versus an Elimination diet’ (TRACE) study. This is the first study to determine the short- and long-term effectiveness and cost-effectiveness of two dietary treatments as initial addition to care as usual as a treatment trajectory for children with ADHD.

We will substantially improve upon previous studies by implementing the intervention in non-commercial mental health centers, including blinded and objective measurements, and comparing two dietary treatments with care as usual. Also, understanding the biological effects could inform clinicians to potential markers and targets for preventative or individualized treatment. For this reason, we also examine the underlying biological mechanisms (e.g. mechanisms in the gut and brain) of dietary treatments (TRACE-BIOME and TRACE-MRI studies). We collect blood, stool and saliva samples.

The TRACE study is a two arm randomized control trial: participants are randomized to either an elimination diet or a healthy diet. The comparator arm includes children who are being treated with care as usual. Currently, we included in each dietary treatment arm about half of the targeted participants (N=81 in each dietary group). In the care as usual group, we included about one third of the targeted participants (N=60).

We hope to finish inclusion around January 2020.   am really looking forward to the results and hope to share this with you in a couple of years! If you have any questions, feel free to contact us via trace@karakter.com

References:

(1) Nigg, J. T., Lewis, K., Edinger, T., & Falk, M. (2012). Meta-analysis of attention-deficit/hyperactivity disorder or attention-deficit/hyperactivity disorder symptoms,         restriction diet, and synthetic food color additives. Journal of the American Academy of Child & Adolescent Psychiatry, 51(1), 86-97. https://doi.org/10.1016/j.jaac.2011.    10.015 . Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321798/

(2) Izquierdo Pulido, M. L., Ríos Hernández, A., Farran, A., & Alda, J. Á. (2015). The role of  diet and physical activity in children and adolescents with ADHD. Recent Advances in Pharmaceutical Sciences V, 2015, Research Signpost. Chapter 4, p. 51-64.  Link: http://diposit.ub.edu/dspace/bitstream/2445/67543/1/T_1444299316Munozv%204.pdf

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What makes some of us more likely to drive over the speed limit, participate in extreme sports or make decisions that can impact health over time? Risk-taking behavior has distinct subtypes (for example disinhibition, sensation seeking, calculated risks, impulsivity) that develop due to the complex interplay of different factors: our lifestyle and environment, our personal susceptibility (genetic and biological variants) and a wide range of psychological effects.

In the study of Strawbridge and colleagues (2018) the goal was to identify genetic determinants of this trait. This approach has the potential to improve our understanding of impulsive behavior across different psychiatric disorders. It can also help later on to explore the possible overlap between mental illnesses and physical health.

„Would you consider yourself a risk taker?” This was the question posed to 116,255 participants, aged 40 to 69, from the UK Biobank project, a large population cohort containing a wide range of sociodemographic and medical information. Roughly one-quarter answered yes, they were the ’risk takers’ group.

A subset of participants took part in a prolonged follow-up occasion as well, where the same question was asked enabling an assessment of response consistency. Reproducibility was quite good, 81% of all participants responded consistently, 13% inconsistently, while in 6% the data was missing.

Genetic loci associated with risk-taking behavior were explored using the genome-wide association study approach. The authors identified one potential locus on chromosome 3 (CADM2) consistently, which was previously implicated in cognitive and executive functions.

Considering the entire genome using the polygenic risk score approach, the authors found, that the genetic variants that make us risk-prone also make us more likely to develop mental illnesses, such as bipolar disorder, schizophrenia, attention-deficit hyperactivity disorder, and post-traumatic stress disorder.

This trait has not only significant positive genetic correlations with a range of mental health disorders, but also with smoking, lifetime cannabis use and body mass index (BMI). The latter implies the possibility that this finding could be followed up in a study exploring the nutritional aspects of impulsivity as well.

Overall, using dimensional approach for traits (from “normal” to pathological) rather than discrete diagnostic categories could be helpful for finding the common ground in the neurobiological underpinnings across psychiatric disorders. From this point of view, risk-taking behavior is also a complex and important phenotype for investigations.

You can find the full research article here.

Strawbridge, R. J., Ward, J., Cullen, B., Tunbridge, E. M., Hartz, S., Bierut, L., Horton, A., Bailey, M. E. S., Graham, N., Ferguson, A., Lyall, D. M., Mackay, D., Pidgeon, L. M., Cavanagh, J., Pell, J. P., O’Donovan, M., Escott-Price, V., Harrison, P. J., & Smith, D. J. (2018). Genome-wide analysis of self-reported risk-taking behaviour and cross-disorder genetic correlations in the UK Biobank cohort. Translational Psychiatry, 8. https://doi.org/10.1038/s41398-017-0079-1

This was co-authored by  Tünde Kilencz, a psychologist and research assistant at Semmelweis University, Department of Psychiatry and Psychotherapy in Budapest, Hungary.

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The reason why I look at impulsive behavior is because mental disorders are the single largest contributors to disease burden in Europe. Impulsivity and compulsivity increase the risk of psychiatric disorders, especially Attention Deficit Hyperactivity Disorder, alcohol and drug abuse disorders, conduct disorder and antisocial disorders (including aggression). The urgency of addressing impulsivity and compulsivity is additionally strongly supported by the fact that these problems increase the risk for mortality.

My name is Yvonne Willemsen and I have started my PhD track at Radboud University in the Netherlands in October 2017. For my project I will assess the association between nutrition, gut microbiota composition and impulsive behavior in toddlers and young adolescents. In the following paragraphs, I will explain the first study that I am currently conducting.

Many previous studies have examined the association between nutrition and executive functions. Executive functions are cognitive processes in the brain that contribute to regulating thoughts and behaviors. Executive functions can be roughly divided into three core functions, namely: inhibitory control, working memory, and cognitive flexibility. Inhibitory control, which can be interpreted as the opposite of impulsivity, is necessary to suppress impulses. It is also an important core function of executive functions, as it supports working memory and cognitive flexibility.  To date, studies have examined the association between nutrition and executive functions in general (1). Whether nutrition is related to inhibitory control specifically (in toddlers and young adolescents) is something that still needs to be investigated.

The next step of my study is to understand how nutrition is associated with inhibitory control. To explain a possible mechanism, we will look at the gut microbiota. The reason why the gut microbiota is a point of interest is because gut microbiota can secrete molecules that may influence brain function, and thus may influence inhibitory control (2). This connection between the gut and the brain is also known as the gut-brain axis. Gut microbiota composition can change according to nutritional intake, and can therefore play a role in the gut brain axis (3). To assess the association between nutrition, gut microbiota and behavior in toddlers and young adolescents, we will use questionnaires and different behavioural measures.

  1. Cohen, J. F. W., Gorski, M. T., Gruber, S. A., Kurdziel, L. B. F. & Rimm, E. B. The effect of healthy dietary consumption on executive cognitive functioning in children and adolescents: a systematic review. Br. J. Nutr. 116, 989–1000 (2016). Link
  2. Rogers, G. B. et al. From gut dysbiosis to altered brain function and mental illness: mechanisms and pathways. Mol. Psychiatry 21, 738–748 (2016). Link
  3. Oriach, C. S., Robertson, R. C., Stanton, C., Cryan, J. F. & Dinan, T. G. Food for thought: The role of nutrition in the microbiota-gut–brain axis. Clin. Nutr. Exp. 6, 25–38 (2016). Link
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