Why do some of us find it more difficult to exercise than others? Why do we prefer investments or mortgages to fixed income? Why do we find it difficult to answer test questions if the wrong answers deduct points? All these questions are important in the field of economics, psychology or education, but also in our daily lives, and are related to the concept of devaluation of rewards.

In the early 1970s, psychologist Walter Mischel demonstrated how many young children are unable to wait a short period of time for two treats in his famousMarshmallow test. Likewise, the work of Kahneman and Tversky, and Thaler have been awarded Nobel Prizes in Economics (in 2002 and 2017) for their studies on what influences how we humans decide. For example, we are all "risk averse", i.e. afraid to take risks, but this common characteristic is particularly pronounced in some people.

Many subsequent works have shown that three of the aspects core topic that influence the value of a award for an individual would be how safe award is (i.e., the risk), how much effort it takes to get it, or when we are going to get it.

Attention deficit hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder in children and adolescents, with a worldwide prevalence of 3-5%. In adults, data on the frequency (prevalence) of the disorder are similar.

ADHD is characterised by a continuous pattern of hyperactivity, impulsivity and/or inattention that negatively affects academic, social, or family functioning from childhood and throughout life. As in children with ADHD, adults share the symptoms of inattention, hyperactivity and impulsivity. However, these symptoms vary with age. Hyperactivity is the symptom that decreases the most, followed by impulsivity and inattention remains about the same. Adults with ADHD are less likely to show obvious hyperactive behaviours, instead they may show inner restlessness and constant mental activity, thus internalising their hyperactivity.

Some common problems related to ADHD in adulthood would be:

- concentration problems
- difficulty with organization
- problems with routines
- problems completing tasks
- depression and/or leave self-esteem
- inner restlessness
- poor time management skills
- impatience and frustration

Likewise, in some cases adult ADHD is associated with non-beneficial lifestyles, including risky behaviors, substance use, or sedentary lifestyles. In fact, although ADHD is sometimes thought of as a school-only problem, the disorder has important consequences for individuals with ADHD. ADHD negatively impacts social relationships, health, and final, quality of life.

One specific aspect of the consequences of ADHD may be that young people with the disorder may devalue rewards differently than people without ADHD when making decisions in their daily lives, and that this is also related to different health-related lifestyles. It is these aspects that we sought to assess in our project.

César Soutullo, team member of research, explains the characteristics of ADHD in adults.

B During the last decades, the knowledge of ADHD in adults has experienced an increase in different areas of study (clinical, neuropsychological, neuroimaging and Genetics). In particular, one of the areas that has experienced the greatest progress is therapeutics, especially in relation to psychopharmacology. Despite this, the issue and the quality of the programs of study on the efficacy of psychopharmacological and psychological treatment is lower in this population than in children.

It is recommended that treatment (as well as diagnosis) be carried out by a team multidisciplinary, including at least a psychiatrist and a clinical psychologist. In addition, it is advisable that the treatment approach be multimodal, i.e., that it covers not only the clinical setting, but also the family, school or work setting. It may also be advisable to link up with the nearest association or Foundation.

There are two main branches of treatment for adult ADHD, pharmacological and psychological. Combined treatment, which includes the use of psychotropic medication in conjunction with other psychological and social approaches, has been shown to be the most effective in adult ADHD.

Pharmacological treatments

A number of effective and well-tolerated psychotropic drugs are now available for the treatment of adult ADHD. These drugs can help to reduce the symptoms of the disorder. They are classified into two main groups according to their chemical characteristics: stimulants and non-stimulants.

The first group (stimulants) is made up of drugs of the amphetamine family such as methylphenidate. Methylphenidate is the most widely used stimulant. There are three pharmaceutical presentations of methylphenidate: one immediate-release, which requires three daily intakes, and two extended-release, which require a single morning dose. A characteristic of this drug is its very short effect deadline and its short life average (i.e., the short time it remains in the body).

In the second group (non-stimulants) are all those drugs that, having demonstrated usefulness in reducing symptoms, are not stimulants. Atomoxetine is the best studied non-psychostimulant drug in adults and, therefore, the one with the indication for treatment of ADHD in this population. Atomoxetine can be administered either as a single dose (morning) or in two doses (morning and midday).

All medications seek to increase the amount of a subject neurotransmitter (i.e., a subject molecule that facilitates the transmission of information between neurons) called catecholamines since there is evidence that ADHD is characterized by a lack or dysfunction of this neurotransmitter.

Psychological treatments

Psychological interventions are helpful in the treatment of the disorder, although structured approaches such as cognitive behavioural therapy and psychoeducational interventions have shown positive results in studies. Both types of therapy can be carried out in an individual or group format.

Cognitive-behavioural therapy, a structured intervention adapted to the characteristics of the disorder and each patient, is the most effective psychological approach to treat ADHD in adults. It consists of the application of cognitive and behavioural techniques to address the main difficulties present in this disorder, such as time management, problem solving or impulse control.

Psychoeducational interventions aim to provide adequate information to both the patient and family about the disorder (aetiology, prognosis and associated factors), its treatment and the management of certain situations. They can be used as therapies in themselves or as a component of a more extensive therapy.