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.

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

It must have been mid-October 2017 that Oliver (8 years of age) and his family were referred to us by one of our co-workers. “Parents would like to know more about a dietary intervention for Oliver’s ADHD as opposed to medication. Oliver is falling behind at school due to attention difficulties and impulsivity. In addition to that, he has difficulty maintaining friendships and gets into fights every other day.” After screening Oliver’s behavioural problems both at home and at school, we concluded that Oliver fulfilled all inclusion criteria and none of the exclusion criteria: he and his family were most welcome to participate in our dietary intervention at New Brain Nutrition.

Oliver’s family consists of his mother, father and younger sister Liz (6 years of age). In addition to that, his grandmother and grandfather are closely involved in raising Oliver and Liz: they take care of their grandchildren two days a week (after school). One of the major difficulties that parents had to deal with in implementing the diet was that the grandparents were somewhat sceptical about the intervention. While grandfather had this ‘Well, boys will be boys’ kind of view on Oliver’s behaviour, his grandmother was more into a ‘The way to a man’s heart is through his stomach’ perspective, which led to pampering Oliver and Liz with candy on a daily basis. This called for some extra support from our researchers (who are also clinicians) in explaining the treatment to the grandparents. Eventually, all were on the same page and well-instructed before the start of the dietary intervention.

chocolate gooey browniesAt the start, parents filled out a baseline questionnaire on the behavioural problems (i.e. hyperactivity, impulsivity, attention deficits), physical problems (i.e. headache, stomach-ache, changes in appetite) and emotional difficulties (i.e. tantrums, mood swings) that Oliver dealt with. These measures were monitored by his parents on a daily basis (on a 5-points scale) for the following five weeks. These data were collected by our dietician on a weekly basis, while the dietician also monitored their adherence. In the first week, Oliver and his grandmother made a few dietary mistakes, but from the second week onwards, all became accustomed to the dietary protocol. Oliver’s mother encouraged all family members by setting shared goals on a weekly basis. For example, if the children earned a certain amount of stickers, they would go to the swimming pool by the end of first week, to a play-farm by the end of the second week, and so on.

After three weeks, a drop in behavioural problems was seen (from an average of 5/5 at baseline to an average of 3/5 after 3 weeks), while emotional difficulties (and the related fights with peers) were diminished after three weeks (from 5/5 on average at baseline to an average of 1/5 after 3 weeks). Physical complaints were not reported (1/5 on average at both baseline and after 3 weeks). His attentional problems however remained severe (4/5 on average at both baseline and after 3 weeks).

The decrease in problems persisted until the end of the first five weeks of the dietary intervention. Since the attentional problems kept interfering with Oliver’s school performances, school provided Oliver with a noise-cancelling headset after the fifth week.

The overall results led Oliver and his family to decide to proceed with the re-introduction of eliminated foods. This however was done after the holidays (Saint Nicholas, Christmas), which parents considered too much of a challenge to combine with a strict diet. Today (mid-February), Oliver and his family are in the midst of the re-introduction of foods. Every two weeks one new product is re-introduced in bulk. Oliver’s mother turns out to be a genius in creating attractive snacks and dishes that adhere to the dietary protocol. And Oliver? He is very proud of himself for sticking to the diet!

(Editor’s note: New Brain Nutrition is conducting numerous studies on food elimination diets and other nutrition and supplement topics through 2022.  Subscribe to our blog for updates.  We look forward to sharing a lot of information and findings with you.)

Vitamin B and ADHDThere is a well-documented relationship between dietary factors, health and human behavior. Severe malnutrition produces neurological and psychiatric symptoms. It is also assumed that dietary factors play a role in common mental disorders, such as ADHD, but this is less established and more difficult to investigate. A few studies have documented a beneficial effect of dietary interventions and vitamin supplements in ADHD in children and adults. To examine the nutritional status in ADHD, Landaas et al.(1) recently compared blood vitamin levels in 133 adult ADHD patients and 131 healthy controls. In the ADHD group there was a clear overrepresentation in the group with low levels of vitamins B2, B6 and B9.

It is yet unclear whether these vitamin levels are a) associated with ADHD symptoms, or b) whether they are the result of altered dietary intake, or c) metabolism in ADHD patients. However, it is possible that the differences reflect dietary habits that are different in a subgroup of ADHD patients and controls. Dietary habits are established early during life and may last into adulthood. It is possible that suboptimal dietary habits may precipitate, exacerbate or maintain symptoms of ADHD. More research in larger samples is obviously needed to clarify these issues. Over the next five years in our project, entitled “Effects of Nutrition and Lifestyle on Impulsive, Compulsive, and Externalizing behaviours,” we expect to gain much more insight into these connections.  We will share our findings with you.  Stay tuned!!

(1) BJPsych Open. 2016 Nov; 2(6): 377–384. Published online 2016 Dec 13. doi:  10.1192/bjpo.bp.116.003491
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5153567/