What do rewards have to do with mental health problems?

Photo by Jacqueline Munguía

What do you think of when I say “rewards”? Perhaps you think of the points you collect every time you shop or the badges you get when playing a videogame. Well, then you’re right!  A reward can be anything. A good grade, going on a trip with friends, a smile, and even that dessert you crave in the middle of the night. Rewards are any stimuli with the potential to make us seek and consume them, and if we like, we will probably want to get them again [1].

Actually, you crave that dessert because you ate it once, and you liked it so much that your brain learned that eating that dessert again will make you feel good. This happens because of a neurotransmitter called “dopamine” released when you eat the dessert, giving you that little rush of pleasure. Now your brain knows what you like and will want more of that.

By now, you probably have realized that rewards are present in virtually everything we do in our daily lives. That is why seeking and consuming rewards are considered to be a fundamental characteristic of human behavior. These rewards that we keep consuming guarantee that we stay alive by eating and drinking water, for example. Rewards also have a huge influence on how we experience positive emotions, motivate ourselves to perform tasks, and learn new things [2].

What about the relationship between rewards and mental health problems?

Although rewards are natural stimuli that make us keep doing healthy and nurturing things, it can also become a problem. Rewards are not the problem itself, but some people can have an unhealthy behavior towards rewards. That’s where mental health problems come in. Did you know that most mental health conditions have alterations in how rewards are processed in the brain? It’s so common that these so-called reward processing alterations are now considered a “transdiagnostic feature,” meaning we can find them across different mental health conditions [3].

Reward processing is a term to refer to all aspects related to how we approach and consume rewards. For instance, how you respond after getting a reward (responsiveness), how motivated you are to go after a reward (drive/motivation), how impulsive you are when trying to get new and intense rewards (fun-seeking/impulsivity). So, as you can see, it’s not only about getting the rewards, but many different things play a role in a simple action we do.

Let’s think of an example: You are going to a party with your best friends. You are motivated to go out with your friends because you’re always happy when you are around them [this is the drive/motivation]. Once you are at the party, you meet your friends, talk, laugh and are happy you decided to join because you’re feeling that rush of pleasure [this is the responsiveness aspect]. At some parties, things can get a bit out of control, and some people might do risky things on the spur of the moment, like binge drinking. You refuse to binge drink because you thought of the risks, and you don’t want to be in trouble later [that’s the third aspect, the fun-seeking/impulsivity].

Now, let’s think of how that party would be for people with reward processing alterations. In the case of a very high drive, they would be super motivated to hang out with friends. On the other hand, if they have low responsiveness, they wouldn’t be able to have fun at the party even though all of their friends are there and the party is super fun. Lastly, in the case of high fun-seeking/impulsivity, they wouldn’t think of the risks and consequences and engage in binge drinking anyways.

As I mentioned before, these alterations play a role in different mental health conditions. They can affect one or more aspects of reward processing, and they can be either lower or higher than average. For example, people with ADHD can show higher risk-taking, meaning that they are more susceptible to take big risks without thinking about the consequences [4]. This impulsive behavior might be a reflection of the altered fun-seeking aspect of reward processing. Another example is the lack of interest in social interactions in people with autism spectrum disorders [5]. This lack of interest might reflect a reduced drive/motivation to go after social rewards.

These are just some examples of what reward processing alterations might look like in the context of mental health problems. There are still a lot of open questions. As part of my PhD research, I am trying to answer some of them. For example, which came first? Are reward processing alterations causing mental health problems, or are they just mere symptoms of these conditions? If you want to learn more about this topic, stay tuned as more blog posts will come!

Dener Cardoso Melo is a PhD candidate at the University Medical Center Groningen (UMCG). He is using data from the CoCA project together with other datasets to investigate the potential causal role of reward processing alterations in different mental health conditions.


  1. Schultz, W. (2015). Neuronal reward and decision signals: From theories to data. Physiological Reviews, 95(3), 853-951. doi:10.1152/physrev.00023.2014
  2. Wise, R. A. (2002). Brain reward circuitry: Insights from unsensed incentives. United States: Elsevier Inc. doi:10.1016/S0896-6273(02)00965-0
  3. Zald, D. H., & Treadway, M. T. (2017). Reward processing, neuroeconomics, and psychopathology. Annual Review of Clinical Psychology, 13(1), 471-495. doi:10.1146/annurev-clinpsy-032816-044957
  4. Luman, M., Tripp, G., & Scheres, A. (2010). Identifying the neurobiology of altered reinforcement sensitivity in ADHD: A review and research agenda. Neuroscience and Biobehavioral Reviews, 34(5), 744-754. doi:10.1016/j.neubiorev.2009.11.021
  5. Stavropoulos, K. K., & Carver, L. J. (2018). Oscillatory rhythm of reward: Anticipation and processing of rewards in children with and without autism. Molecular Autism, 9(1), 4. doi:10.1186/s13229-018-0189-5

The notorious evening chronotype and my master’s thesis

Almost every person, healthy or not, suffers from occasional problems with sleep and circadian rhythm. In the modern days of 24/7 smartphone use and transcontinental flights, our internal body clock is having a hard time adjusting to the external cues. For the persons suffering from mental health issues, their impaired sleep cycle can be one of the cornerstone problems of daily living. Sleep problems have been confirmed to be a first symptom, consequence, or even a cause of such psychiatric conditions as major depression, bipolar disorder, ADHD, autism, substance abuse, and even aggressive behaviour. Their strong relations, however, have not been studied systematically and broadly just yet.

Why study the circadian rhythm?

Circadian rhythm is our inner clock that regulates a lot of important processes in the human body, including the sleep/wake cycle, the release of hormones and even the way we process medicines. This clock is run by the brain region called the hypothalamus, which piles up a protein called CLK (referring to “clock”), during the daytime. CLK, in turn, activates the genes which make us stay awake, but also gradually increases the creation of another protein called PER. When we have a lot PER, it turns off CLK production and makes us ready to sleep. As CLK is getting lower, this causes a decrease in PER, so that the process starts again with elevating CLK waking us up. This cycle happens at around 24-hour intervals and is greatly influenced by so-called zeitgebers, or time-givers, like light, food, noise and temperature. When our retina neurons catch light waves, the suprachiasmatic nucleus in our brain stops the production of the hormone called melatonin that induces sleep and starts producing noradrenaline and vasopressin instead to wake us. This is the exact reason why you cannot fall asleep after watching a movie at night.

Figure 1. The smart protein CLK wakes us up and its friend PER gets us to sleep.

Sometimes our body clock fails to function, as in the case of jetlag when we feel bad after changing a time zone or social jetlag when we have to start work early at 8 am. It can go as far as a circadian rhythm disorder meaning you have either a delay or advancement of sleep phases or an irregular or even non-24-hour daily activities preference. However, in the general population, a small variation in the rhythm is quite normal and is usually referred to as a chronotype. It defines your preference of when to go to sleep and do your daily activities and is divided into 3 distinct versions. The radical points of these variations include a morning chronotype, or “larks”, who go somewhat 2-3 hours ahead of the balanced rhythm, and an evening chronotype, or “owls”, who are a little delayed. The larks feel and function better during the first half of the day and go to bed rather early, while the owls prefer to work in the evenings and go to bed and wake up naturally late. The third chronotype is the in-between, balanced version of these two.

Figure 2. The ‘owls’ seem to have questionable personalities and suffer from psychiatric conditions more often!

What’s my study about?

Previous research has shown that many psychopathologies are linked to an evening circadian preference. For my master thesis research, I am investigating whether we can identify specific profiles in sleep and circadian rhythm problems that are linked to specific mental health problems. There was even a curious study where researchers linked the Dark Triad personalities, which include people with tendencies for manipulation, lack of empathy, and narcissism, to the evening chronotype. Maybe this leaves some evidence for the famous quote that “evil does not rest”. However, there’s a great variation in sleep duration and perceived quality of sleep in patients with various diseases. We hope to divide such persons into more or less accurate groups with a sleep profile that would predict and aid the correct diagnosis of one or the other mental health condition.

The psychopathologies are included in our study as so-called dimensions, which look at each psychiatric syndrome not as with a norm/pathology cut-off but rather as a continuum of symptoms severity. This approach allows us to see if the sleep/circadian profile we identify refers to mental health in general or can be a distinguished part of a certain psychiatric condition. It might be that all dimensions, like depression and autistic spectrum disorders, have an evening chronotype and some non-specific sleep problems. Alternatively, we might find out that a person with symptoms of depression would sleep more or less than average and go to bed later, whereas a person with anxiety would go to sleep later as well but wake up at night very often despite an average summed up sleep duration.

The circadian rhythm changes throughout a lifetime from an early to an evening chronotype towards adolescence and then gradually shift back to the earlier preference with older age. Across the whole lifespan people constantly face varying quality of night sleep. Moreover, each psychiatric condition has a particular age of onset and sometimes changes its character with time. These are the reasons why our study will also look at how the sleep/circadian profiles change within the development phases from children (4-12 years) to adolescents (13-18) to adults (19-64) to the elderly (≥65) and if they affect males and females differently.

Why would it matter?

Should we discover distinct links between the profiles of sleep/circadian problems and certain conditions, other studies can then look into whether these profiles could be the reasons behind developing a mental health condition. It’d be interesting to finally learn what is a chicken and an egg in each profile-disease relation. For instance, should we really treat ADHD patients with melatonin and bright-light lamps instead of stimulants?

Figure 3. Maybe if we adopt a typical cat’s lifestyle, we get less mental health problems. 🙂

Dina Sarsembayeva is a neurologist and a research master’s student at the University of Groningen. She is using the data from the CoCa project to learn if the chronotypes and sleep problems can be turned into profiles to predict specific psychiatric conditions.

Further reading

  1. Walker, W. H., Walton, J. C., DeVries, A. C. & Nelson, R. J. Circadian rhythm disruption and mental health. Transl. Psychiatry 10, (2020).
  2. Logan, R. W. & McClung, C. A. Rhythms of life: circadian disruption and brain disorders across the lifespan. Nature Reviews Neuroscience vol. 20 49–65 (2019).
  3. Jones, S. G. & Benca, R. M. Circadian disruption in psychiatric disorders. Sleep Med. Clin. 10, 481–493 (2015).
  4. Taylor, B. J. & Hasler, B. P. Chronotype and Mental Health: Recent Advances. Curr. Psychiatry Rep. 20, (2018).

Prevalence and cost of ADHD comorbidity

Do individuals with ADHD more often suffer from depression, anxiety, substance abuse or severe obesity, than individuals without ADHD? Are there differences between men and women in how often this is the case? Does having ADHD in addition to one of these conditions result in higher health care costs?

The short answers to these questions, are yes, yes and yes. In the CoCA-project, researchers have investigated these questions using very large datasets including Scandinavian birth registries that contain information of millions of people. This allows us to get a better understanding of how often conditions occor, how often they occur together, and how often they occur in men vs women. Furthermore, we have investigated health insurance data from Germany to study patterns of health care costs associated with ADHD and its comorbid conditions.

The interpretation of these data is however not simple. That is why we have recorded a webinar with dr. Catharina Hartman from Groningen, The Netherlands. She is the leader of these studies and can explain what these findings can and cannot tell us. The webinar ends with implications for policy makers and health care professionals, based on these findings.

These are the world’s most high ranking experts on ADHD

Who are the most knowledgeable people about ADHD in the world? According to the website expertscape.com, these are professors Stephen Faraone (SUNY upstate University), Samuel Cortese (University of Southampton) and Jan Buitelaar (Radboud University Nijmegen).

What’s more, several scientists who are involved in our research consortia that investigate ADHD (i.e. Aggressotype, CoCA, IMpACT, Eat2beNICE) are top-ranked in this list of more than 30.000 possible experts in the field. These include Stephen Faraone, Jan Buitelaar, Philip Asherson, Barbara Franke, Joseph Antoni Ramos-Quiroga, Henrik Larsson, Catharina Hartman and Pieter Hoekstra. What this means is that the ADHD research that we do, and that is often reported on in this blog, is lead by the world’s top ADHD experts.

‘Our’ top-ranked ADHD experts. From left-to-right: Stephen Faraone, Jan Buitelaar, Philip Asheron, Barbara Franke, Joseph Antoni Ramos-Quiroga, Henrik Larsson, Catharina Hartman, Pieter Hoekstra.

How is an expert defined?

The website expertscape was started by John Sotos when he was looking for an expert on Parkinson’s disease to treat his uncle. This turned out to be more difficult than he thought. As John Sotos was a doctor himself, he luckily had a large network of doctors that he could contact about this. But this made him realise that people who don’t have such a network, would not be able to find out who the most knowledgeable persons are on a particular topic. He therefore created this website expertscape.com

The way the website works is quite simple: it searches for academic, peer-reviewed publications by a certain person on a certain topic. The more someone has published on a topic, the higher this person is ranked. Thus,  “[a]n expert is not just someone who knows a lot about a particular topic. We additionally require that the expert write about the topic, and be involved at the leading edge of investigation of the topic.”

This means that the site is actually not a very good tool to find a good doctor. As the website acknowledges “a great doctor has many important qualities beyond expert knowledge of your very specific medical condition.” However, it does mean that the website is pretty good at providing a simple overview of who has a lot of scientific knowledge about a specific topic.

So are they really experts?

In the past years I have met with most people in the top of this list, and I dare say that they are very knowledgeable indeed. Each of them has been working in the ADHD field for a considerable amount of time and has added important new insights into ADHD through research and publications. What I find most striking from this list however, is that most of these experts work together in consortia and international networks. And that is how the field really moves forward: by combining the knowledge of all these experts.

Several of these experts have also written for this blog:


Source: http://expertscape.com/ex/attention+deficit+disorder+with+hyperactivity


This blog was written by Jeanette Mostert. Jeanette studied brain connectivity in adult ADHD during her PhD. She is now dissemination manager of the international consortia CoCA and Eat2beNICE.