Many people are familiar with the occasional desire for food rich in fat and refined carbohydrate. Some people’s craving is never satiated and develops into an addiction-like attraction towards highly processed foods and consequently an increased risk of obesity, diabetes and cardiovascular disease. Substance use disorder is common among people with mental disorder, and new research suggests that this also applies to food addiction.
The cocktail of fat, sugar, salt and flavourings in fast food is intentionally designed to target the brain’s reward centre and provide pleasure. However, for some people, this highly processed junk food only provides brief satisfaction before they need more. Food addiction is a recognized and growing problem in many countries, and researchers recently reported that 9% of adults in Denmark meet the criteria for food addiction. It is well established that many individuals with mental disorder have alcohol and other substance use disorders, and a recent study from Denmark found that food addiction was very prevalent among individuals with mental disorder.
“Our recent study, which is the most thorough to date, confirmed our hypothesis. One quarter of individuals with mental disorder in Denmark seem to have lost control of their food intake, even though it is harming them. Food addiction was particularly prevalent among individuals with eating disorder, depression, personality disorder and schizophrenia,” explains a researcher behind the new study, Christina Horsager Pedersen, physician and PhD, from the Research Unit for Child and Adolescent Psychiatry, Aalborg University Hospital.
Although the researchers do not yet know the specific causal mechanisms underlying the link between food addiction and mental disorder, they believe that their study could provide an opportunity to re-evaluate the treatment of people with mental disorder and obesity who also meet the criteria for food addiction.
“Instead of conventional diet and exercise treatment programmes, we should probably consider a more psychotherapeutic approach, inspired by the treatment of substance use disorders, to help individuals with mental disorder to obtain a healthier lifestyle without obesity and its comorbidities such as diabetes and cardiovascular disease,” says Christina Horsager Pedersen.
Criteria for food addiction
Over the last decade, studies have shown that highly processed foods, ready meals and fast food rich in fat and refined carbohydrate can be addictive. Researchers refer to this condition as “food addiction”, since it has several behavioural and psychological similarities with the abuse of psychoactive substances such as alcohol, cannabis, amphetamine and cocaine.
“The symptoms of food addiction include loss of control, inability to cut down, continued use despite physical and emotional consequences and much time spent, with negative effects on social life and daily activities. Other symptoms include craving, withdrawal and tolerance, the latter describing the need to eat more and more to get the wanted feelings from eating, such as reducing negative emotions or increasing pleasure,” explains Christina Horsager Pedersen.
People must experience several of these symptoms to meet the criteria for food addiction. In addition, the symptoms must be so severe that they affect daily life and interpersonal relationships to an extent that inhibits and burdens the person significantly. You do not have food addiction if you just occasionally eat a whole bar of chocolate on a Friday night. Nevertheless, 9% of adults in Denmark meet the criteria for food addiction.
“Many of these people spend so much time acquiring and eating food that this negatively affects school attendance or work performance. Further, they cannot stop despite the obvious negative consequences that are both psychological and physiological. Since previous studies clearly show that many people with a mental disorder have alcohol and drug use disorders, we aimed to investigate the prevalence of food addiction in this group,” says Christina Horsager Pedersen.
Competing for reward systems in the brain
A total of 5,000 individuals aged 18–62 years were randomly selected from the Danish Psychiatric Central Research Registry equally distributed across eight major diagnostic categories of mental disorders: substance use disorder, psychotic disorder, affective disorder, anxiety and stress-related disorder, eating disorder, personality disorder, autism spectrum disorder and attention-deficit hyperactivity disorder.
“We invited them to participate in an online questionnaire-based survey that included the Yale Food Addiction Scale 2.0, which assesses the symptoms of food addiction. This enabled us to estimate the proportion of respondents with food addiction in each diagnostic group. The prevalence varied substantially and overall, 24% met the criteria for food addiction versus 9% in the general population,” explains Christina Horsager Pedersen.
Food addiction was particularly common among people with affective disorder, including depression (29%), personality disorder (29%) and schizophrenia (27%). Somewhat surprisingly, respondents with attention-deficit hyperactivity disorder had a relatively low prevalence (12%) although these individuals often experience comorbid substance use disorder.
“The explanation behind this finding may be that more potent substances than food compete for the same reward systems in the brain. This correlates very well with the fact that the people who already had an addiction disorder also had the lowest prevalence of food addiction,” says Christina Horsager Pedersen.
Food addiction as a specific treatment target
Food addiction is substantially more common among women than among men. More than half the women with schizophrenia had food addiction versus 12% of men, and overall, 32% of the women had food addiction versus only 13% of men.
“We see the same pattern in the general population, with 14% of women and 7% of men meeting the criteria for food addiction. In addition, we confirmed that food addiction is also linked with obesity among people with a mental disorder. Although the new study provides many of the answers we sought, it raises at least as many new questions that need to be clarified to understand and consequently treat people with food addiction,” explains Christina Horsager Pedersen.
Therefore, in future studies the researchers will aim to investigate the underlying mechanisms behind the association between obesity and food addiction and examine how food addiction affects people with a mental disorder. This includes examining how treatment with psychotropic medication affects the eating pattern. This research will attempt to identify unique risk factors that can help both to prevent food addiction and to treat those affected by it more effectively.
“We now want to investigate how food addiction influences the link between mental disorders and obesity, and the development of related metabolic diseases such as type 2 diabetes. For some people, food addiction may be a specific target for treatment or prevention of obesity and comorbidities such as type 2 diabetes,” says Christina Horsager Pedersen.
Additional treatment tool
Although food addiction is not yet a formal diagnosis, growing evidence indicate that it is an independent disorder and that certain types of food can be addictive. However, food addiction remains a relatively new concept.
“Many questions still need to be answered, which is also reflected in the considerable increase in research in this field in recent years,” explains Christina Horsager Pedersen.
Nevertheless, Christina Horsager Pedersen thinks that the new results already can be useful in exploring alternative frameworks for understanding obesity and thus inspire the treatment of people with both mental disorder and obesity.
“Including food addiction as a potential contributing mechanism causing obesity can potentially add to our current toolbox for treatment and prevention. Because of the conceptual and phenotypic similarities between food addiction and substance use disorder, basing treatment strategies on interventions from the field of addiction disorders has been suggested. For instance, this could include reducing symptoms of craving, and withdrawal via treatment involving cognitive behavioural therapy, pharmacotherapy and psychoeducation. Further, the food addiction construct has implications from a public health perspective. If we are to succeed in stopping the obesity epidemic, we should probably be more aware of our surrounding food environment and the constant exposure to cheap and potentially addictive foods,” concludes Christina Horsager Pedersen.