Table 1 Practice Recommendations for children and adults with comorbid ADHD and ASD: identification and assessment

1. Due to the level of complexity involved, assessments should only be offered by healthcare practitioners with appropriate training and skills.

2. A comprehensive assessment should include detailed information about the person’s development and functioning across settings spanning many years (see text for topics). Symptom presentation may change over time for both conditions.

3. Semi-structured clinical interviews that explicitly map onto diagnostic criteria may be helpful as they guide the assessor to complete a comprehensive developmental and clinical interview.

4. A helpful precursor to any interview is to ask the parent/carer to look at childhood developmental health records, photographs and school reports and/or to think about key transitions in the child’s life (such as moves from home, change of school).

5. The assessor should take a parsimonious approach, i.e. they should not ‘double count’ symptoms present in both ADHD and ASD.

6. It is critical to consider the extent to which the individual’s functioning is age appropriate and obtain examples of how difficulties interfere in their functioning and development at home and in educational or work environments.

7. Compared with males, females with ADHD may present with fewer disruptive behavioural problems and those with ASD may have lower intellectual abilities.

8. The assessor should consider the potential impact of cultural issues, e.g. use of eye contact and type of play.

9. Whenever possible, collateral information should be obtained from independent sources, e.g. parent/carer, teacher interviews, observation in school and/or other settings, adults, perusal of school, college and/or employment reports.

10. Informants who are family members may have ADHD or ASD (perhaps undiagnosed), which may impact upon their judgement of ‘typical’ behaviour.

11. Symptoms of both ADHD and ASD may be masked for many reasons, which may cloud clinical judgement, e.g. accommodations may be applied at home and the individual may have developed compensatory strategies, which may minimise deficits in social communication and interaction, and/or skills to ‘camouflage’ difficulties in specific situations or for a brief period of time.

12. There are high rates of comorbidity associated with both ADHD and ASD, and the assessment should identify whether co-existing comorbid disorders are present. Young children presenting with an initial diagnosis of ASD should be continually monitored through development for ADHD, particularly given that the average age of diagnosis for the two conditions is discrepant.

13. A risk assessment should be included (see text for topics) together with an assessment of dysfunctional strategies. For example, in young people and adults, these might be alcohol or substance misuse to manage social anxiety or low mood.

14. Assessment of capacity may be warranted for adults with ASD with severe impairments who require substantial support.

15. Rating scales are not diagnostic instruments but tools to aid diagnosis and monitor clinical progress. If used to screen, individuals receiving borderline scores (i.e. falling just below cut-offs) should not be excluded from referral for a comprehensive clinical diagnostic assessment.

16. Norms for many screening tools are often based predominantly on male samples, which may disadvantage their use in females.

17. Reporting tools such as visual representations of mood states or visual analogue scales will facilitate the assessor to obtain subjective information from individuals who have difficulty identifying or describing their thoughts, feels and sensations.

18. Observational assessments, including neuropsychological tests, are not diagnostic. They augment clinical decision-making by providing useful information regarding a person’s functioning.

19. An intellectual assessment should always be considered, together with an assessment of adaptive functioning, and a low threshold applied for their administration.

20. An intellectual assessment may be helpful for children and young people in school or further education to determine cognitive strengths and weaknesses, establish goals of treatment and target appropriate educational interventions.

21. For both conditions, uneven cognitive profiles are commonly seen across verbal abilities, performance abilities, working memory and processing speed, reflecting variable strengths and weaknesses.

22. The outcome of the assessment should include a diagnostic formulation as well as an aetiological formulation that includes protective, predisposing, precipitating and perpetuating factors that inform a comprehensive care plan which takes into account of the needs of the individual and how these may be met across settings (see text for topics). It should also include a Positive Behavioural Support plan, which aims to provide a consistent approach between different caregivers. The care plan should be shared with all relevant parties, as appropriate (including educational establishments, with consent).