Comparison of the burden of illness for adults with ADHD across seven countries: a qualitative study

Worldwide, adults are increasingly diagnosed with ADHD. Typically seen as a problem of childhood, and once thought to be something that people outgrow, clinical and epidemiological research have identified ADHD as a persistent condition in adulthood for at least a large minority[1‐4]. In children, ADHD is a commonly diagnosed neuropsychiatric condition associated with hyperactivity, impulsivity, and inattention, and is estimated to occur in 3–7% of school-aged children[5]. In the United Kingdom, prevalence is estimated to be 3.62% in males and .85% in females[6].

In a meta-analysis of global prevalence in the general population, researchers estimated adult ADHD occurs at a rate of approximately 4% worldwide[7]. Persistence of ADHD in adulthood is strongly related to childhood symptom profile, including symptoms associated with the attentional plus impulsive-hyperactive type, symptom severity in childhood, comorbid major depressive disorder, high comorbidity of three or more child-adolescent disorders, paternal anxiety-mood disorder, and parental antisocial personality disorder[8]. Prospective studies evaluating the incidence of ADHD that persists into adulthood for those diagnosed with the condition in childhood range widely in their prevalence estimates, from 5% to 66%[9‐13]. This wide range is largely attributed to methodological differences in the very few studies conducted and distinctions in the diagnostic criteria utilized[7, 14]. However, ADHD among adults is understood to be a relatively common psychiatric condition with an estimated prevalence in the general population ranging between 2% and 6%[15]. The adult prevalence in the United States ranges from 2.9% to 4.4%[3, 12, 16, 17]. Available estimates of adult ADHD in Europe range from 2.8% to 7.3% (France 7.3%; Germany 3.1%; Italy 2.8%; The Netherlands 5.0%)[18].

Importantly, the rate of recognition of ADHD contributes to the range of diagnosis estimates across regions and health systems. Recognition is, in turn, affected by many factors including challenges of diagnosis, varying definitions of functional impairments, adaptive strategies of individuals that may mask or minimize symptoms, problems of self-report and insight into childhood symptoms, and media representations that influence the perceptions of both doctor and patient[19]. These factors may contribute to stigma of the patient and his or her symptoms of ADHD. Additionally, health systems and insurance structures also impact diagnosis rates, reflecting national values and norms that create either obstacles or a pathway towards diagnosis. For example, focus group participants from Italy in this study often traveled to neighboring countries to receive both diagnosis and medications for ADHD. This reflected the view of the health system, and its practitioners, that ADHD was primarily a disease of childhood.

Many individuals are diagnosed with ADHD as adults without having been formally diagnosed in childhood. Currently, an adult diagnosis of ADHD requires a retrospective analysis of an individual’s childhood for behavioral aspects that meet the criteria of childhood ADHD. Researchers of ADHD in adulthood argue that the disorder does not occur spontaneously in adulthood[2]. Although there is some continuity of core ADHD characteristics, the manifestation of symptoms varies in a developmental manner. For example, whereas children with ADHD may experience difficulties across all core symptom areas (inattention, hyperactivity, impulsivity), adults with ADHD are thought more likely to have inattentive symptoms than hyperactive or impulsive symptoms[17, 20].

Evidence suggests that ADHD symptoms continue to impair functioning, well-being, and health-related quality of life in adulthood[21‐24]. Adults with ADHD often experience multiple life difficulties, including depression or anxiety, anti-social behaviors, lowered socio-economic status due to work-related issues, and substance abuse[2, 4, 11, 25, 26]. Adults with ADHD are at risk for social skill deficiencies due to difficulties in affect recognition[27] and anger expression[28]. Women with ADHD report more depressive symptoms, greater anxiety and stress, and lower self-esteem than women without ADHD[29, 30]. In addition to the effect of ADHD on the individual, the societal impact of adult ADHD is significant as adults with ADHD commit more antisocial acts[25], are arrested more often[25], and are at increased risk for motor vehicle accidents than those without ADHD[28]. ADHD is relatively common in the workplace globally. As demonstrated in a ten-country study, approximately 3.5% of working adults have ADHD with related impacts on their work productivity[18]. From an economic perspective, healthcare costs are greater for adults with ADHD compared with those without ADHD[31]. Using a cost of illness framework, annual costs range between $12,005 and $17,458 per individual, with a total annual societal cost in childhood and adolescence of approximately $42.5 billion dollars (2005 estimates)[32]. Social stigma is also associated with behaviors exhibited by those with ADHD, compounding lifelong social suffering[33]. Thus, ADHD, as currently understood, imparts substantial morbidity on those with the disorder.

Over the past few decades, prevalence data have suggested that the United States incurs higher rates of diagnosis for ADHD generally, and this has catalyzed concern that ADHD might be an explicitly “American condition”, interpreted through specific socio-cultural structures and expectations for individuals. As researchers have noted, this may be due to the fact that research of ADHD has centered in the United States, and that there are discrepancies in the use of the diagnostic criteria[7]. The aim of this study was to qualitatively understand the ADHD experience in different countries of North America and Europe, with a focus on the similarities of its burdens across countries and health systems.

This analysis was derived from fourteen focus groups and five one-on-one telephone interviews held in seven countries: Canada, France, Germany, Italy, The Netherlands, United Kingdom, and United States (two focus groups in each country). The five telephone interviews were conducted in Italy in order to balance the sample size with that of the other countries. Adults with a medical diagnosis of ADHD were recruited for each group either through local clinical experts or ADHD advocacy groups. Participants were compensated for their time spent attending the group. The study was approved by an ethics committee.

The focus groups were semi-structured and conversational, and constructed with an emphasis on the burden of illness for the participants. The focus group script was developed based on a literature review, feedback from expert clinicians from each country included in the study, and prior experience of the authors with this population. The guide was designed to elicit commentary in several areas, including how the participants were diagnosed, their childhood experience of ADHD, and daily life, social, psychological, and physical functioning. All focus groups in English speaking countries were conducted by the first author, an experienced group facilitator. In non-English speaking countries, the groups were conducted by native speakers who were experienced facilitators and trained by the first author on the focus and intent of the discussion guide. Transcripts were translated into English and transcribed by different transcribers, and then coded thematically by one analyst (the second author). A preliminary code list was derived from the focus group script, and codes were added to the list as new themes emerged during the review of each transcript. Transcripts were reviewed and coded at least three times. First, they were reviewed to assess basic content and the emergence of new themes. This was followed by a second in-depth coding session. Finally, they were reviewed a third time for accuracy and consistency in the coding process. Additional review of transcripts occurred when a new code was added, to insure that all incidences of that theme were captured during the coding process. This method is especially strong for revealing similarities across transcripts; however, the regular review and re-review of transcripts also potentially highlights differences between them. Throughout these comparisons, an effort was made to look for differences by country.

When appropriate, codes were merged to avoid redundancy and/or split to reveal more specificity in the themes discussed by participants. Codes were then grouped into domains. The coding process was undertaken by one individual (the second author), in consult with the first author. The end result was a full coding schema that was descriptive of the collective experience of adult ADHD, spanning from physical symptoms to participants’ psychological and social responses to them. Representative sample comments are provided following each domain summary to support the qualitative findings. This descriptive coding method is consistent with grounded theory and other thematic analysis methodologies[34]. These participant commentaries were chosen for 1.) descriptive quality and 2.) central focus on the theme in question. They do not reflect any preferences for specific treatments or medications.

A total of 103 focus group participants, 52 men and 51 women, participated in the 14 focus groups. The average size of a group was 7 participants, with a range of 3 (one of the focus groups in Italy) to 9 participants. In addition, five telephone interviews were conducted in Italy in order to include more participants from that country. This brought the total number of participants to 108, representing 51 women and 57 men. The mean age of patients was 36 years, and the mean length of time since the diagnosis of ADHD was 8 years (range 0 to 46 years). Thirty-two percent of the study sample was diagnosed with ADHD in childhood. The self-reported lifetime average number of ADHD medications taken for the sample was 1.7, with 55% currently undergoing treatment with a prescribed ADHD medication. As expected in an ADHD population, 42% of the subjects reported that they also had other mental health diagnoses besides ADHD.

See Table1 for the full sample description.

As noted earlier, the focus group script emphasized the burden of illness for ADHD. As a result, participants talked about dilemmas of life affected by ADHD. They also spoke of positive aspects of life with ADHD, although to a lesser degree because of the emphasis on the burden of illness. Their comments were grouped analytically into four domains: ADHD Medical History (diagnosis, symptoms and medication use), Life Experience, Daily Life Impacts of ADHD and Psychological and Social Impacts of ADHD. Each broad domain contained several subdomains or themes. In the sections that follow, we detail the burden of illness associated with ADHD. The number of respondents and percentage of sample that discussed the issues explored in a given domain is listed with the table heading.

These findings strongly suggest that, on an international scale, the experience of ADHD in daily life is consistent, despite the socio-cultural differences that may exist between these seven countries. These adults experienced the impacts of ADHD on functioning and well being similarly across national boundaries. Participants in these focus groups felt themselves to be different from others, often from childhood, and reported that receiving a diagnosis of ADHD as adults can be accompanied by substantial difficulty. They retrospectively identifed difficulty interacting with others in childhood, and noted a great deal of difficulty in school life and with the educational process. They also believed that ADHD has impacted their lives in very significant ways, especially with regard to education and career, and their statements support clinical research conclusions that people with ADHD are prone to troubles with addictive behaviors and other activities thought to be risky or dangerous. Navigating daily life presented considerable challenges for these adults as they reported difficulties with social relationships of all types, including with work colleagues, family, friends, and acquaintances. Together, these challenges appear to contribute to psychological conflict and diminished well-being for many. Given that 42% of these adults reported other mental health conditions along with their ADHD, some caution is suggested in attributing all impairments reported solely to their ADHD. However, in general, the statements of subjects who reported other mental health conditions and the greater majority (58%) who did not report other conditions were not substantively different.

Furthermore, these adults agreed on the key presentation of symptoms of ADHD: hyperactivity, impulsivity, inattention, and disorganization without regard to their cultural and social biases. It may not be surprising that people who have been diagnosed with a condition, presumably in accordance to standardized symptom criteria, might agree on the symptoms most central to the condition itself. This is the situational background of this study, which recruited participants who had received a diagnosis of ADHD into focus groups to explore ADHD. This is also this study’s major limitation. Similarly, the fact that participants in these focus groups retrospectively identified problems in childhood also resonate with the explicit diagnostic criteria that a retrospective assessment of childhood is included in the diagnostic process. However, despite the standardized criteria of biomedicine, one might surmise that a condition that centers on observable behaviors might be experienced differently across national and cultural borders, resulting in different impairments in daily life and lifespan activities due to interpretation bias by society or culture. However, these focus groups suggest that this is not the case for these seven countries and that the burden of illness is, instead, quite similar for adults with ADHD.

Limitations for this small study include a self-selection bias by the participants. As interested volunteers for the study, they may not have been an adequate representational sample for the entire national populations of adults with ADHD. In addition, the study’s focus on the burdens of ADHD may not have captured fully the perceptions these individuals may share with regard to its positive qualities. The emphasis on illness in the focus group script was concomitant with an emphasis on debility, rather than ability. Furthermore, these methodological limitations point to the need to confirm the results quantitatively.

It should be noted that not all countries participating in this study have a medical system that relies on similar diagnostic categories, general criteria for diagnosis or the availability of ADHD medications for adults. For example, in Italy and France, ADHD is recognized primarily as a condition of childhood and commonly used medications for ADHD are not prescribed or generally available for adults. Thus the participants in the focus groups held in Italy spoke of the need to travel to other countries for both diagnosis and medicines, thus making their diagnosis experience and treatment somewhat more challenging and emotionally difficult than those of individuals in the United States, Canada, or the United Kingdom. Relatedly, health systems differences, while not explored to a great extent in these focus groups, may be the more salient difference across national boundaries than the diagnosis and experience of ADHD. In a world with global access to biomedical information and related media, coupled with international diagnostic guidelines, differences between countries may be less pronounced.

An important finding of this study centers on medication use. Among those who are prescribed and use medication for their ADHD symptoms, there appeared to be general satisfaction that the medications were efficacious and helpful to them. However, these individuals generally did not take their medications in compliance with their prescriptions, but as they saw fit based upon their interpretation of their signs and symptoms. This opens up a potential area of investigation into the impacts of adherence and non-adherence to medications for ADHD and its effects on long-term burden of illness. Further study investigating the effects of intermittent and fluctuating use of medication for ADHD symptoms in adults, conducted through both qualitative and quantitative methodologies, may lend more insight into the complexities of adult ADHD treatment. Furthermore, although not definitive, the commentaries of these respondents identified that side effects, perceived by some to be deleterious, led to a refusal of the medication itself. These patient-reported outcomes should be considered in the development of future treatment modalities, whether these treatments are pharmaceutical or behavioral.

Findings from this study suggest that additional qualitative research is needed to further elucidate socio-cultural differences across countries generally with regard to ADHD in order to better understand the context within which people experience their disease. This ethnographic research might include expert interviews with clinicians from each country, including those whose knowledge centers on ADHD and those whose practice may be more general, as well as attitudes from the lay public who do not have a diagnosis of ADHD. Parsing the role of social stigma from the symptoms themselves could be used to understand how social experiences impact the burden of illness in the case of ADHD. Focus groups segregated by the time of diagnosis (childhood or adulthood) and across multiple countries would provide additional insight into a very intriguing area of research.

In addition to ethnographic investigation, there are many other intriguing questions associated with ADHD in adults, clinical recognition, and health system contributions to the burden of illness. These include the levels of knowledge and acceptance of ADHD in adults among potentially treating practitioners, the accessibility of medical intervention and services within specific health systems, and the availability of multiple treatment medications. Within patient experience, it would also be interesting to be able to understand 1.) the relationship between the numbers of years diagnosed with ADHD and burden of illness; 2.) co-morbid mental health conditions and adherence to treatments; and 3.) feelings of social isolation and burden of illness.

Last, all of the countries selected for this study are considered “western” countries. As such, each has similar social and economic structures for education, work, and social relationships. It is not surprising, therefore, that participants in this study might have similar life stories to tell about the obstacles they faced as people with a diagnosis of ADHD. What is of importance, however, is the extent to which adults with a diagnosis of ADHD agree upon the burden of illness and general life impacts. Similar qualitative investigation into the burden of illness of ADHD in adults that includes countries outside North America and Europe would be an important contribution to this field.

ADHD is a consistent and stable diagnostic category across North America and Europe among those who carry the diagnostic label as adults. This appears to be true even in countries in which doctors typically do not recognize ADHD among adults. As these data demonstrate, adults in the United States, Canada, United Kingdom, France, Germany, The Netherlands, and Italy shared similar narratives in primary domains of functioning and well-being and agreed on the fundamental symptoms of ADHD. This suggests that the burden of illness and impacts of ADHD are similar across these seven countries and not limited to the United States alone.