Appropriate screening for the following disorders, where clinically indicated, may be helpful in some cases before conducting further assessment:
- obstructive sleep apnoea
- iron-deficiency anaemia
- vitamin B12 and folate deficiency
- malabsorption problems (e.g. coeliac disease)
- petit mal epilepsy
- severe substance dependence
- head injury (neuropsychological assessment can be helpful here).
It is important not to rule out ADHD simply because other disorders have already been identified.
It is important to recognise that many mental and physical health problems can cause difficulties with attention, impulsivity, hyperactivity and organisation, but these conditions are often episodic or later in onset, unlike ADHD which is present from childhood and persistent. ADHD can co-occur with any DSM-5 disorder and typically does – ADHD rarely occurs on its own (Table 1). It is important not to rule out ADHD simply because other disorders have already been identified. There are many patients whose anxiety and depression improves once any underlying ADHD is treated. Treating underlying ADHD improves the treatment of comorbid conditions and quality of life. It can be time consuming to tease apart a patient’s developmental history and the often wide array of presenting symptoms when ADHD is suspected, so a series of longer consultations should be scheduled. The Canadian Attention Deficit hyperactivity Disorder Resource Alliance (CADDRA) guidelines are an excellent source of information for GPs who wish to increase their assessment skills in ADHD.9
How is ADHD treated?
Current treatment guidelines suggest that the mainstay of treatment for moderate- to-severe ADHD in adults is stimulant medication, either methylphenidate or dexamfetamine.9-12 Statistics from the Pharmaceutical Benefits Scheme in 2015 indicate that the rate of prescription of ADHD medication in adults is vastly lower than the prevalence of the disorder in the adult population: 0.1 to 0.5% of the adult population received a prescription for an ADHD medication yet the prevalence of ADHD in adults is about 4 to 5%.13 ADHD in adults is far from being overdiagnosed and overtreated. There are high costs to the individual and our society when ADHD remains untreated (Box 3).
The good news is that most patients respond well to stimulant medications. For patients who are unable to tolerate stimulant medication, do not find it effective or have substance misuse issues, a nonstimulant medication may be trialled. In some cases, a combination of stimulant and nonstimulant medication may be helpful (Table 2).