Abstract
Objective:
To compare the characteristics of childhood-onset versus late-onset Attention Deficit Hyperactivity Disorder (ADHD) in a sample of treatment-seeking patients.
Method:
Among total of 101 adult patients who were recently diagnosed for ADHD, using the Diagnostic Interview for Adult ADHD (DIVA 2.0), 56 subjects exhibited childhood-onset ADHD, versus 45 displayed late-onset ADHD. Both groups were compared according to their sociodemographic, clinical, and neuropsychological features, providing crude (OR) and adjusted odds ratios (aOR), and their 95% confidence intervals [95% CI].
Results:
Compared to late-onset ADHD, patients with childhood-onset had a lower educational score, (OR = 0.52; 95% CI [0.35, 0.76]), a greater score of impulsivity (aOR = 1.09; 95% CI [1.03, 1.16]), an increased number of hyperactive-impulsive ADHD symptoms (aOR = 1.9; 95% CI [1.46, 2.47]), and higher rates childhood trauma (aOR = 1.07; 95% CI [1.01, 1.13]), cannabis use disorder (aOR = 1.07; 95% CI [1.01, 1.13]), and working memory impairment. No difference was observed concerning age, sex, psychiatric symptoms, quality of life, and autonomy.
Conclusion:
Childhood-onset adult ADHD displayed a more severe profile, relative to late-onset ADHD.
Introduction
Attention Deficit with or without Hyperactivity Disorder (ADHD) has long been conceptualized as a neurodevelopmental disorder with an onset of symptoms and impairments occurring in childhood, that is, before the age of 12 years (American Psychiatric Association [APA], 2015). Prospective studies of clinic-referred children with ADHD indicated that approximately 15% would continue to meet diagnostic criteria in adulthood, and 65% will continue to have subthreshold impairing symptoms as young adults (Faraone, Biederman, & Mick, 2006) contrasting with the old “childhood-limited” theory of ADHD (Lange et al., 2010). As a result, in their fifth version, the Diagnostic and Statistical Manual of Mental Disorders criteria for ADHD elevate the age-of-onset threshold from 7 to 12 years and lower the symptom threshold from 6 to 5 at each symptom domain for individuals aged 17 years and older (APA, 2015).
More recently, the results of several lifelong cohort studies suggested that ADHD in adolescence and adulthood is not always a continuation of childhood ADHD, and that ADHD may thus arise after childhood (Agnew-Blais et al., 2016; Caye et al., 2016; Moffitt et al., 2015). Consequently, it has been suggested that ADHD could be diagnosed after the DSM age-at-onset cut-off (Asherson & Agnew-Blais, 2019). Two main theories have attempted to explain what late-onset (LO) ADHD can represent. A first hypothesis it that, in individuals with LO ADHD, symptoms in childhood have been compensated for, owing to a supportive environment and/or greater cognitive skills, while other theories suppose that LO ADHD is actually the clinical manifestation of other psychiatric disorders but not ADHD, for example, the consequences of substance use (Agnew-Blais et al., 2016; Taylor et al., 2022).
The clinical comparison of CO versus LO forms of ADHD have led to conflicting results concerning neuropsychological assessment, genetic risk, or environmental factors (Asherson & Agnew-Blais, 2019). If some studies reported no difference in the impairment of neuropsychological functions (Faraone, Biederman, Doyle, et al., 2006), others showed different profiles of cognitive performance deficit in CO versus LO ADHD (Moffitt et al., 2015) suggesting these two forms could be etiologically discrete disorders. As mentioned above, it has also been suggested that adults with LO ADHD had subthreshold symptoms in childhood, (Asherson & Agnew-Blais, 2019; Faraone & Biederman, 2016), with a higher level of cognitive functioning (Agnew-Blais et al., 2016; Moffitt et al., 2015), which decompensated later into the full criteria for ADHD, in particular when socio-professional demands are higher. The aim of our study was to compare the clinical and neuropsychological features of CO versus LO ADHD, in a French outpatient population diagnosed with ADHD.
Method
Study Population
Participants were adult patients who had consulted in the diagnosis center for adult ADHD of Lyon, and had received a confirmed diagnosis of adult ADHD, based on the Diagnostic Interview for ADHD in adults (DIVA) 2.0 (Pettersson et al., 2018). The recruitment period was Jan 2019 to Dec 2021. The DIVA 2.0 was undertaken by a trained clinician, usually with the help of the patient’s family. Mini International Neuropsychiatric Interview (MINI) 5.0.0 was used to exclude possible other axis-1 psychiatric diagnoses that could question the final diagnosis of ADHD. The study pertained only to individuals with a positive diagnosis of ADHD. Patients already receiving treatment for ADHD, that is, methylphenidate, amphetamine derivatives, atomoxetine, or bupropion, respectively, at the time of the assessment, were excluded.
Clinical and Functional Measures
The DIVA 2.0 is a validated structured interview for the assessment of adult ADHD according to DSM-IV-TR diagnostic criteria. It provides a diagnostic result for ADHD, as well as elements on the clinical subtype of ADHD, that is, inattentive, hyperactive, or mixed, respectively. Moreover, the DIVA 2.0 allows to differentiate childhood-onset ADHD (i.e., current ADHD diagnosis with reported ADHD symptoms above diagnosis cut-off before 12-year-old) versus late-onset ADHD (i.e., current ADHD diagnosis with reported ADHD symptoms below diagnosis cut-off before 12-year-old) (Ramos-Quiroga et al., 2019). We also retrieved the number of inattentive and hyperactive-impulsive symptoms during childhood to assess the severity of inattentive and/or hyperactive-impulsive symptoms.
In addition, participants underwent a series of self-questionnaires assessing their level of anxiety, using the State-Trait Anxiety Inventory (STAI-A and STAI-B) (Ercan et al., 2015), depression, using the Beck Depression Inventory (BDI-II) (Beck et al., 2011), childhood traumas, using the Childhood Trauma Questionnaire (CTQ) (Scher et al., 2001), sleep impairments, using the Pittsburgh Sleep Quality Index (PSQI) (Fabbri et al., 2021), quality of life, using the World Health Organization Quality of Life (WHOQOL-Bref) questionnaire, autonomy (World Health Organization., s. d.), using the World Health Organization Disability and Autonomy Scale (WHODAS-2) questionnaire, impulsivity, using the impulsive behavior scale (UPPS-P) (Whiteside et al., 2005), tobacco use, using the Fagerström Test for Nicotine Dependence (FTND) score (Moolchan et al., 2002), alcohol use, using the Alcohol Use Disorder Identification Test (AUDIT) score (Gache et al., 2005), and cannabis use, using the Cannabis Use Disorder Identification Test–revised (CUDIT-R) (Adamson et al., 2010).
An additional clinician-based assessment explored the use of non-prescribed psychostimulant drugs in the previous month (yes vs. no), age (in years), sex (male or female), education level, using the International Standard Classification of Education (ISCED), body mass index (BMI, in kg/m2).
Neuropsychological Assessment
Participants underwent a complete neuropsychological assessment using multiple tests: TAP (Test for Attentional Performance) for phasic alert, divided attention, sustained attention, and motor inhibition (Zimmermann & Fimm, 1992), D2 for selective attention (Brickenkamp & Zilmer, 2011), WAIS-IV Digit Span for working memory (Wechsler, 2012), Stroop test for cognitive inhibition (Stroop, 1935), TMT (Trail Making test) for cognitive flexibility (Arbuthnott & Frank, 2000), and the multiple errands test, for planning skills (Shallice & Burgess, 1991), a test designed to assess the patient’s ability to take account of several instructions simultaneously. The test consists of an instruction sheet with a shopping district map showing several stores to which the patient must go for various errands, considering multiple constraints.
To assess the impairment of each cognitive function, measures were transformed into percentile ranks, standard scores or z-scores. Here, the thresholds proposed by Ceccaldi et al. (2015) were used. In view of the lack of consensus in the literature regarding cognitive impairment in individuals with ADHD, the lower cut-off values were considered as pathological, in order to encompass cognitive weaknesses in cognitive deficits. Thus, for percentile ranks, values below 16 are considered pathological. For z-scores, values below −1 are considered failed. For standard scores, values below 7 are considered pathological. The executive functions were investigated in this study and the criteria for dysexecutive syndrome were met when participants had at least two executive impairments in the different tests (Fonctions exécutives et pathologies neurologiques et psychiatriques, 2019).
Statistical Analyses
Descriptive statistics are presented as the mean and the standard deviation (m ± SD) for quantitative variables, and the number and percentage (n, %) for categorical variables. Bivariable comparisons between childhood-onset and late-onset ADHD were conducted using Mann-Whitney test for quantitative variables, and chi-squared test for categorical variables. Logistic regression models were built, to explore the associations between the type of ADHD (i.e., CO vs. LO), and the other parameters, which were the dependent variables. Models provided raw and adjusted odds ratios and their 95% confidence interval ([a]OR, 95% CI). Adjustment variables were age, sex, and level of education. No multivariable models were built for neuropsychological tests, as the calculation of the results already integrated the same adjustment variables.
Ethics
The study was performed in accordance with the guidelines and regulations described by the Declaration of Helsinki and Jarde law on human research ethics (Toulouse et al., 2018). This study was approved by the CNIL (French National Commission on Informatics and Liberties) (approval reference number: MR-004-2020-006).
Results
Population
During the inclusion period, 184 patients were referred by other medical centers for ADHD assessment, and, for 123 of them, the diagnosis of ADHD was confirmed, using the DIVA 2.0. Twenty-two patients were excluded because they were already medicated for ADHD. Of the 101 participants included, 56 (55.5%) met the criteria for CO ADHD, whereas 45 (45.6%) met the criteria for LO ADHD.
Demographic and Clinical Description
Descriptive results of the two groups, as well as bivariable comparisons, are presented in Table 1, while the results of multivariable comparisons are presented in Table 2. There was no difference in age between both groups. In the CO ADHD group, a significantly lower proportion of women (28.6%) were found compared to the LO group (44.4%). However, this difference did not remain significant in multivariable model analyses.
Socio-Demographic, Clinical and Neuropsychological Characteristics of the Study Population.
Note. ISCED = International Standard Classification of Education; DIVA 2.0 = Diagnostic Interview for ADHD in adults; BMI = Body Mass Index; STAI; State-Trait Anxiety Inventory); A = State; B = trait; BDI = Beck Depression Inventory; CTQ; Childhood Trauma Questionnaire; PSQI = Pittsburgh Sleep Quality Index; WHOQOL= World Health Organization Quality of Life; WHODAS-2 = World Health Organization Disability and Autonomy Scale; UPPS = impulsive behavior scale; FTND = Fagerström Test for Nicotine Dependence; AUDIT = Alcohol Use Disorder Identification Test; CUDIT-R = Cannabis Use Disorder Identification Test–revised.
Using D2.
Using Test of Attentional Performance.
Using WAIS-IV Digit Span.
Using Trail Making Test.
Using Stroop test.
Using the multiple errands test.
At least two executive impairments in the different tests.
Bivariate and Multivariate Analysis.
Note. ISCED = International Standard Classification of Education; BMI = Body Mass Index; STAI = State-Trait Anxiety Inventory; A =State; B = trait; BDI = Beck Depression Inventory; CTQ = Childhood Trauma Questionnaire; PSQI = Pittsburgh Sleep Quality Index; WHOQOL = World Health Organization Quality of Life; WHODAS-2 = World Health Organization Disability and Autonomy Scale; UPPS = impulsive behavior scale; FTND = Fagerström Test for Nicotine Dependence; AUDIT = Alcohol Use Disorder Identification Test; CUDIT-R = Cannabis Use Disorder Identification Test -revised.
Adjusted on sex, age, and ISCED level.
p < .5. **p < .1. ***p < .01.
Participants in the CO group had a significantly lower educational level, relative to the LO group, that is, a lower ISCED score (OR = 0.52; 95% CI [0.35, 0.76]). They also displayed a lower rate of childhood trauma (aOR = 1.07; [1.01, 1.13]). Concerning the clinical features, a lower BMI was found in the CO group (aOR = 0.90; [0.82, 0.99]), as well as a higher level of impulsivity (aOR = 1.09; [1.03, 1.16]), a higher number of hyperactive-impulsive childhood ADHD symptoms (aOR = 1.9; [1.46, 2.47]) and inattentive childhood ADHD symptoms (aOR = 2.6; [1.75, 3.76]) at the DIVA.
Age at onset of first ADHD symptoms were below 12 for the CO ADHD group. For the LO group, 59.5% were 12 years-old or younger at onset, while 16.7% were adolescents, i.e., aged between 12 and 18 years, and 23.8% were adults, that is, aged 18 years or more when first symptoms occurred.
CO subjects had higher rates of cannabis and alcohol use disorders. The difference remained significant for cannabis use only in the adjusted regression model (aOR = 1.07 95% CI [1.01, 1.13]). There was no significant difference between groups concerning the level of anxiety, depression, sleep impairment, tobacco use, quality of life, or autonomy. Mean levels of anxiety (state and trait) were elevated in both groups, as well as the level of sleep disorder risks. Mean depression scores were moderated in both groups.
Concerning quality of life, scores in the four domains (physical, psychological, social, and environmental) were lower than the normative population in previous studies (Murphy & Murphy, 2006), meaning that CO and LO have a poorer quality of life in these different domains. Poor level of functioning/autonomy was also retrieved in both groups according to the WHODAS scale.
Neuropsychological Data
As presented in Tables 1 and 2. There was no difference concerning neuropsychological testing between CO and LO ADHD, except for working memory, which tends to be more impaired in CO group (42.9% had an impairment in working memory) compared to LO group (24.4%) (OR = 2.32; 95% CI [0.98, 5.49]). Among the different cognitive functions assessed, sustained and divided attention, and planification were the most impacted in both groups (more than 50% of participants in each group).
Discussion
Our study aimed to compare the clinical and neuropsychological characteristics of participants with either CO or LO ADHD in a clinical population with a current diagnosis of ADHD. Our results emphasize that CO ADHD that persisted during adulthood had more severe functional impairments, relative to subjects with LO ADHD, with a lower educational level, higher level of impulsivity, more hyperactive-impulsive symptoms, increased risk of childhood trauma, cannabis used disorder, and increased impairment in working memory.
Our results are in line with other studies, demonstrating that CO ADHD is a more severe ADHD (Agnew-Blais et al., 2016; Lopez et al., 2017), with a higher level of hyperactive-impulsive symptoms (Solanto, 2019), and functional difficulties, such as a lower education attainment (Agnew-Blais et al., 2018). In contrast with some previous studies, we did not find that LO ADHD was more associated with substance use disorder risk and therefore the hypothesis that LO ADHD could be a consequence of substance consumption (Agnew-Blais et al., 2018; Moffitt et al., 2015; Sibley et al., 2018) is not corroborated by our results. For both CO and LO ADHD, we found high level of anxiety and depressive symptoms, low quality of life and autonomy, as well as high level of neuropsychological impairment accordingly to previous study (Agnew-Blais et al., 2016; Cooper et al., 2018; Faraone, Biederman, Doyle, et al., 2006). Both CO and LO ADHD are associated with a considerable personal burden.
As previously suggested in the scientific literature, it is plausible, in view of our findings, that individuals LO ADHD were not diagnosed earlier because of a sub-clinical symptomatology. In our population, more than half of the LO ADHD group reported some inattention and/or hyperactive-impulsive symptoms before 12 years of age, even if the number of symptoms was below the diagnosis cut-off.
Also, we found a lower rate of childhood trauma in the LO ADHD group. Childhood trauma could be a reason for early specialized consultation, leading to an earlier assessment of children with trauma-related suffering and an earlier ADHD diagnosis (Chronis-Tuscano, 2022).
Our study had several limitations. Because of its retrospective design, we could not distinguish whether CO ADHD was more severe because the duration of the disorder was longer, or, on the contrary, if CO ADHD occurred sooner in life because the form of the disorder was intrinsically more severe in these individuals. The impact of lifelong medications, including previous ADHD treatments, was not investigated. Moreover, we did not compare the IQ between groups, which would have provided useful pieces of information. In particular, we could not explore the hypothesis that better intellectual performances explain the differential profile of LO versus CO ADHD. Last, although the DIVA scale allows for a retrospective ADHD diagnosis, several studies have identified some potential recall and classification bias for retrospective ADHD diagnosis (Breda et al., 2020; Mannuzza et al., 2002). Our results should thus be interpreted regarding this potential misclassification. It is possible that recall of childhood symptoms was facilitated by a more severe or noticeable symptomatology.
Conclusion and Perspective
Individuals with CO ADHD appeared to have more severe functional features, relative to LO ADHD. Overall, our results are more in line with the hypotheses which suggest that LO ADHD could be a “compensated” form of ADHD, with symptoms that are both less severe and occur later in life. Of course, our findings are retrospective and are based on a single-center study and should be replicated in additional samples and prospective data.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
