Prediction of childhood ADHD symptoms to quality of life in young adults: Adult ADHD and anxiety/depression as mediators

Highlights

• Persistent childhood ADHD may co-occur with ANX/DEP and influence later QoL.

• We identified the mediators on the pathway from childhood ADHD to later adverse QoL.

• Both the severity of adult ADHD and ANX/DEP symptoms had significant meditation effects.

• Childhood ADHD may predict lower QoL in adulthood via persistent ADHD symptoms and ANX/DEP.

Abstract

Childhood attention-deficit/hyperactivity disorder (ADHD) symptoms may persist, co-occur with anxiety and depression (ANX/DEP), and influence quality of life (QoL) in later life. However, the information about whether these persistent ADHD and ANX/DEP mediate the influence of childhood ADHD on adverse QoL in adulthood is lacking. This study aimed to determine whether adult ADHD symptoms and/or ANX/DEP mediated the association between childhood ADHD and QoL. We assessed 1382 young men aged 19–30 years in Taiwan using self-administered questionnaires for retrospective recall of ADHD symptoms at ages 6–12, and assessment of current ADHD and ANX/DEP symptoms, and QoL. We conducted mediation analyses and compared the values of mediation ratio (P_M) by adding mediators (adult ADHD and ANX/DEP), individually and simultaneously into a regression model with childhood ADHD as an independent variable and QoL as a dependent variable. Our results showed that both adult ADHD and ANX/DEP symptoms significantly mediated the association between childhood ADHD and QoL (P_M = 0.71 for ANX/DEP, P_M = 0.78 for adult ADHD symptoms, and P_M = 0.91 for both). The significance of negative correlations between childhood ADHD and four domains of adult QoL disappeared after adding these two mediators in the model. Our findings suggested that the strong relationship between childhood ADHD and adult life quality can be explained by the presence of persistent ADHD symptoms and co-occurring ANX/DEP. These two mediators are recommended to be included in the assessment and intervention for ADHD to offset the potential adverse life quality outcome in ADHD.

Introduction

Attention deficit/hyperactivity disorder (ADHD) is a common neuropsychiatric disorder, characterized by early onset, persistent and pervasive patterns of developmentally inappropriate inattention, overactivity and impulsivity (Biederman et al., 1998, Ingram et al., 1999, Mannuzza and Klein, 2000, Wilens and Dodson, 2004), with high prevalence of 5–10% of school age children (Faraone et al., 2003, Gau et al., 2005, Skounti et al., 2007) and 2–4% of adults (Fayyad et al., 2007, Kessler et al., 2005a, Kessler et al., 2006, Simon et al., 2009). ADHD accounts for 30% to 50% of child referrals to mental health services (MTA Cooperative Group, 1999), leads to substantial functional impairment in wide-ranging domains, especially in educational (Harpin, 2005), family, and peer domains (Bagwell et al., 2001, Hoza, 2007, Wilson and Marcotte, 1996), and influences quality of life (Wehmeier et al., 2010, Klassen et al., 2004, Matza et al., 2005, Pongwilairat et al., 2005, Sawyer et al., 2002, Topolski et al., 2004, Varni and Burwinkle, 2006) among individuals with this disorder. While several researchers have reported that persistent ADHD (Bagwell et al., 2001, Friedman et al., 2003) and co-occurring other psychiatric conditions (Murphy & Barkley, 1996) are associated with these adverse social outcomes in adolescence and adulthood, limited research has examined their relation with quality of life.

Youths with ADHD are at a heightened risk for social, emotional, and adaptive difficulties (August et al., 1998, Hoza, 2007, Nijmeijer et al., 2008, Wilson and Marcotte, 1996), which predict adverse psychosocial outcomes in later life. Since ADHD is more persistent than previous thought and is associated with impairment and comorbidities over the life span (Wilens & Dodson, 2004), data from longitudinal follow-up studies from childhood to adulthood are crucial to advance our understanding of the trajectories of ADHD impact (Ingram et al., 1999). In addition to many long-term follow-up studies of ADHD that focused on different domains of functional impairment, including academic underachievement (Wilson & Marcotte, 1996), reduced vocational opportunities (Barkley, Fischer, Smallish, & Fletcher, 2006) and social maladjustment (Bagwell et al., 2001, Greene et al., 1997), the concept of well-being and quality of life has emerged as an important outcome measure in observation studies (Graetz et al., 2001, Sawyer et al., 2002) and clinical trials (Perwien et al., 2004, Yang et al., 2007) in ADHD as well as other mental disorders (Bastiaansen et al., 2004, Hays et al., 1995, Mendlowicz and Stein, 2000).

The concept of quality of life has been defined in many ways. A relatively well-accepted definition provided by Leidy, Revicki, and Genesté (1999) is that quality of life is an individual's subjective perception of the impact of health status (e.g., disease and treatment) on physical, psychological, and social functioning. Quality of life encompasses more than simply symptom levels and can be distinguished from psychopathology measurement quite well, because it addresses several aspects concerning a person's functional adaptation in his or her everyday life (Bastiaansen, Koot, & Ferdinand, 2005). Although there is an overlap on several parts between instruments designed to measure quality of life and those used to measure functional impairment, the key distinction is that quality of life measures subjectively against an internally rather than externally generated standard (Danckaerts et al., 2010). Functional impairment is usually rated by the clinicians but quality of life is rated by the patients. Functional impairment is integral to the illness, whereas quality of life is a broader assessment of the impact of illness (Sawyer et al., 2002). The main goal of healthcare is to improve patients’ perceptions of their health and the extent to which health problems interfere with their quality of life (Spitzer et al., 1995). Assessment of the quality of life can assist the clinicians to identify areas of life that are particularly difficult for the patients (Danckaerts et al., 2010). Appropriate support and intervention based on the assessment can therefore be engaged (Danckaerts et al., 2010).

Recent western literature documents that significantly lower quality of life in youths with ADHD than healthy controls in several domains such as psycho-social, achievement and self-evaluation domains (Hakkaart-van Roijen et al., 2007, Klassen et al., 2004, Matza et al., 2005, Pongwilairat et al., 2005, Sawyer et al., 2002, Topolski et al., 2004, Varni and Burwinkle, 2006). The degree of adverse life quality outcome was significantly correlated with the severity of ADHD symptoms (Klassen et al., 2004, Matza et al., 2004). Among the three ADHD subtypes, defined according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV): predominantly inattentive type (ADHD-I), predominantly hyperactive/impulsive type (ADHD-HI), and combined type (ADHD-C), individuals with ADHD-C were consistently rated the most impaired (Graetz et al., 2001, Landgraf et al., 2002) and individuals with ADHD-I were reported to have low self-esteem and social and school-related problems (Graetz et al., 2001), but fewer externalizing problems than individuals with ADHD-C or ADHD-HI (Graetz et al., 2001). However, little is known about quality of life in individuals with ADHD in Asian population (Chao et al., 2008).

ADHD symptoms, particularly inattention, commonly persist to adolescence even to adulthood (Biederman et al., 2000, Gau et al., 2010a, Hart et al., 1995). A majority of individuals with childhood ADHD continue to struggle with a substantial number of ADHD symptoms (Wilens, Faraone, & Biederman, 2004) and high levels of dysfunction despite a sizeable rate of syndromatic remission in young and middle-aged adults (Biederman et al., 2000, Das et al., 2012). ADHD symptoms in adulthood are considered to increase the likelihood of vocational underachievement, substance abuse and antisocial and delinquent behaviors (Barkley et al., 2006, Biederman et al., 1998, Kessler et al., 2005a, Torgersen et al., 2006).

However, research about quality of life in individuals with persistent ADHD from childhood to adulthood is quite limited. Similar to their child or adolescent counterparts, adults with ADHD diagnosis (Grenwald-Mayes, 2001, Matza et al., 2007) and ADHD symptoms (Gudjonsson, Sigurdsson, Eyjolfsdottir, Smari, & Young, 2009) appear to have lower quality of life than non-ADHD adults in western populations. Similar results were also found in a school-based survey showing that young adults with ADHD symptoms having poor quality of life in Taiwan (Chao et al., 2008). Self-report of decreased quality of life reflects individual's subjective perception of dissatisfaction with his/her health status that does not explain how ADHD negatively affects quality of life. Although quality of life has been used as one of efficacy measures in clinical trials for ADHD (e.g., Adler et al., 2008, Matza et al., 2006), limited studies have utilized quality of life as a measure to identify specific factors that influence life quality in adult patients with ADHD. These studies showed that ADHD symptom severity (Rimmerman, Yurkevich, Birger, Azaiza, & Elyashar, 2007) and family of origin dynamics (Grenwald-Mayes, 2001) were highly predictive of life quality in adult ADHD patients. Identifying what factors that mediate ADHD to decreasing quality of life in adults with ADHD is warranted to design specific measures for assessment and intervention for individuals with ADHD to improve their life quality and other functional outcomes at adulthood (Agarwal, Goldenberg, Perry, & Ishak, 2012).

Another important issue that drew our attention is the impact of comorbid symptoms on quality of life owing to high comorbidity in ADHD. Several studies reported persistent ADHD may also contribute to incremental psychiatric comorbidities of oppositional defiant disorder, conduct disorder, bipolar disorders, depression, anxiety and sleep problems (Biederman, 2005, Biederman et al., 2006, Gau et al., 2010b, Murphy and Barkley, 1996, Tai et al., 2012). The severity and disability levels of ANX/DEP, a cluster of common minor mental symptoms, are related to social and functional impairment (Hays et al., 1995, Nomura et al., 2000, Ormel et al., 1993, Wells and Trust, 1989) and contributed to various dimensions of quality of life (Hays et al., 1995, Mendlowicz and Stein, 2000). However, little is known about the association between these comorbidities and quality of life in individuals with ADHD. Limited similar data showed that ADHD symptoms were correlated with more severe depression, anxiety, and daytime sleepiness, and poorer quality of life (Chao et al., 2008), and that life satisfaction is negatively correlated with ADHD symptoms and depression anxiety stress rating (Gudjonsson et al., 2009) in young adults. Given the above findings, it is particularly crucial to determine the extent to which the development of ANX/DEP seen in ADHD adults explains the association between childhood ADHD to adverse quality of life in adolescence and adulthood.

In summary, although decreased quality of life in adults with ADHD have been reported in western studies (e.g., Grenwald-Mayes, 2001, Gudjonsson et al., 2009, Landgraf, 2007, Matza et al., 2007, Mick et al., 2008) and one study in Taiwan (Chao et al., 2008), there has been no study reporting the factors mediating the pathway from childhood ADHD to decreased quality of life in adulthood. Moreover, literature documents that children with ADHD symptoms or diagnosis tend to have persistent ADHD (Wilens & Dodson, 2004) and develop ANX/DEP conditions (Gau et al., 2010b, Tai et al., 2012), and that childhood ADHD, adult ADHD symptoms, and ANX/DEP may predict adverse social outcomes (Bagwell et al., 2001, Ormel et al., 1993, Rucklidge et al., 2007) and be associated with declined quality of life at adulthood (Gudjonsson et al., 2009, Hays et al., 1995, Mendlowicz and Stein, 2000, Safren et al., 2010, Taanila et al., 2009). Lastly, there is no such information about how these persistent ADHD symptoms and ANX/DEP mediate the prediction of ADHD to adverse quality of life. Hence, we conducted this study to clarify the role of adult ADHD symptoms and/or ANX/DEP in mediating the pathway from childhood ADHD to quality of life using a nationally representative male sample. Understanding the mediators for quality of life in ADHD could be helpful to assist the clinicians and public healthcare professionals in developing specific intervention strategies to improve the quality of life in individuals with ADHD. We hypothesized that childhood ADHD symptoms would predict the impairment of quality of life. We also anticipated that severity of adult ADHD symptoms and ANX/DEP would be associated with quality of life and mediate the relationship between childhood ADHD and quality of life at young adulthood.