DSM-5,ICD-11,RDoC and ADHD diagnosis

DSM digest

While there has been considerable criticism of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) in general, much of the criticism has utilized child psychiatric examples (Levy, 2012). Frances (2010) argued that the DSM-5 had introduced several new disorders that might overlap with ‘normal behaviour’, and had also loosened requirements for many of the existing disorders, reducing the threshold for adult attention hyper-activity deficit disorder (ADHD) and post-traumatic stress disorder, and adding a diagnosis for ‘temper tantrums’ (disruptive mood dysregulation disorder – DMDD).

The DSM-5 allows a diagnosis of ADHD if ‘several inattentive or hyperactive-impulsive symptoms’ are present prior to age 12 years rather than 7 years, and requires six inattentive or six hyperactive-impulsive symptoms to be present for 6 months in two or more settings. For older adolescents and adults, the DSM-5 requires at least five symptoms. It also requires clear evidence ‘that the symptoms interfere with, or reduce the quality of, social, academic or occupational functioning’. Severity is specified in terms of numbers of symptoms in excess of those required to make a diagnosis. In addition, the predominantly inattentive, predominantly hyperactive-impulsive and combined subtypes were retained. DSM-5 also allows an ADHD diagnosis in the presence of autism.

On the other hand, Polanczyk et al. (2007) conducted a comprehensive systematic review of studies addressing prevalence rates of ADHD/HD worldwide and a meta-regression analysis to understand the reasons of estimate variability. Their findings suggested that the large variability of attention deficit hyperactivity disorder/hyperkinetic disorder (ADHD/HD) prevalence rates worldwide resulted mainly from methodological differences across studies. Their meta-regression analysis emphasized the critical role that methodological variables (i.e. impairment criteria, diagnostic criteria, and source of information) played in the large variability of ADHD/HD prevalence estimates in different geographic locations. When the diagnosis of ADHD/HD was made in the same geographic location but according to a different methodological criterion (i.e. with or without the requirement of functional impairment), estimates ranged from 3.7% to 8.9%. The authors pointed out that the International Classification of Diseases, 10th Revision (ICD-10) and DSM-IV criteria provided very similar lists of symptoms but recommended different ways of establishing a diagnosis, with a lower prevalence predicted by the ICD-10’s requirement for symptom thresholds to be reached in all dimensions, though DSM-5 now also requires two or more settings. ICD-11 is due for publication in 2017 and it remains to be seen how closely the structure of ICD-11 is aligned with DSM-5, given the need for the former to obtain consensus from representatives of over 200 countries.

Research Domain Criteria (RDoC)

The National Institute of Mental Health has embarked on a new approach to psychiatric classification aimed at reflecting functional dimensions based on translational research on gene circuits and behaviour. First (2013) has pointed out that while the DSM and ICD have been highly successful in facilitating communication between clinicians, researchers and administrators, there has only been moderate success in establishing diagnostic reliability when applied by clinicians. According to First, prediction of the course and treatment response is only moderately successful. The goal of RDoC is to relate fundamental domains of behavioural functioning to underlying neurobiological components, conceptualized as disorders in brain circuitry. The RDoC framework has identified five major domains of functioning, each containing more specific constructs. These consist of negative valence systems (fear/extinction, stress/distress, aggression); positive valence systems (reward seeking, reward/habit learning); cognitive systems (attention, perception, working memory, declarative memory, language, cognitive control); systems for social processes (imitation, theory of mind, social dominance, facial expression, attachment/separation fear, self-representation); and arousal regulatory systems (arousal and regulation, resting state activity).

According to First (2013), the RDoC approach represents a true paradigm shift in classification of mental disorders, moving away from defining disorders based on descriptive phenomenology, and focuses on neural circuitry as the fundamental classificatory principle. He points out that RDoC’s impact on future clinical classification in psychiatry will depend on how well the included molecular and neurobiological parameters end up predicting prognosis and treatment response.

Baroni and Castellanos (2015) have reviewed RDoC constructs implicated in ADHD (reward-related processing, inhibition, vigilant attention, reaction time variability, timing and emotional lability). They report that the most frequently used neuropsychological test in ADHD has been the Continuous Performance Test (CPT), though reaction time variability (RTV) has also been found to be present in other conditions. While the RDoC approach promises the greater reliability of objective measurement, it will still be important to maintain careful phenomenological description and relationships in terms of ADHD subtypes, comorbidity and development. Ideally, DSM-5, ICD-11 and RDoC should enrich each other and perhaps RDoC will help clarify interesting relationships between ADHD and comorbid conditions such as autism, oppositional defiant disorder, conduct disorder and personality development, as well as treatment response.