Attention-deficit hyperactivity disorder (ADHD) has been known by various names. In the 1960s, the disorder was given the term ‘minimal brain dysfunction’ (American Psychiatric Association, 1968). Around the late 1980s ADHD was recognised in adults. It is a medical condition that should be treated in order to prevent serious functional impairment to life and resulting costs. Currently in the UK there are limited reports on the prevalence of adult ADHD. We decided to survey all consultant adult and child and adolescent psychiatrists in England and Wales using a semi-structured questionnaire to obtain an estimate of the number of patients with adult ADHD in their current case-load and whether they provide any service for people with adult ADHD.

Method

The contact details of consultant psychiatrists in England and Wales were obtained from the Royal College of Psychiatrists. Local ethical approval was obtained prior to commencement. The anonymous questionnaire (see Box 1) was disseminated along with a covering letter on 6 May 2006 to 1947 consultant psychiatrists. The project duration was 6 weeks from the date of posting. The questionnaire was designed to obtain the numbers of patients with adult ADHD currently receiving treatment from consultant adult and adolescent psychiatrists along with what treatments and diagnosis are used. Respondents were also asked to indicate the age range of patients and gender, who monitors patient medication and approximate number of referrals of suspected adult ADHD received per annum. Participants were also invited to add any other comments they felt were relevant to this study. Microsoft Excel was used for data analysis.

Results

There were 1030 respondents, giving an overall response of 52.9%. Only 197 consultants (19%) offer a service for people with adult ADHD. There were 234 child and adolescent psychiatrists who responded and 12 were providing a service for adults with ADHD; this figure is included in the total number of consultants offering a service (n=197). Some of the child and adolescent psychiatrists commented that they were managing patients until they were 20 years or above. A total of 1345 patients are currently being treated for adult ADHD. It is difficult to predict the prevalence of adult ADHD from this survey. However, Table 1 shows that 1748 new referrals with suspected adult ADHD are received by consultants in England and Wales per year (mean 3.74 per consultant, s.d.=15.27).

Table 1. Responses to the questionnaire by consultants in England and Wales

	n	%
Total responses	1030
Offering a service for adult ADHD	197	19.1
Treating adult ADHD	325	23.9
Patients treated for adult ADHD	1345
Male	995	73.0
Female	350	26.0
Treatment used
Methylphenidate	251	55.0
Atomoxetine	91	19.0
Dexamphetamine	53	11.0
Other	72	15.0
Age group of most patients
18-25 years	209	54.0
25-35 years	126	33
> 35 years	49	13.0
Medication monitored by
General practitioner	54	15.0
Psychiatrist	254	70.0
Combination	56	15.0
Total referrals with suspected adult ADHD per year1	1748
Transfer meetings from CAMHS to adult team1	300	29.1
Consultants using ICD—10 criteria	394	38.3

Discussion

In recent years clinicians and researchers have accepted the validity of ADHD in adulthood (Reference Weiss, Murray and WeissWeiss et al, 2002). Currently there are diagnostic criteria available to diagnose adult ADHD but there is controversy and doubts among clinicians about the validity of these for adult ADHD (Reference McCough and BarkleyMcCough & Barkley, 2004). Longitudinal studies of children with ADHD followed up into adolescence and adulthood have reported high rates of persistent ADHD symptoms (Reference Weiss, Hechtman and MilroyWeiss et al, 1985; Reference Mannuzza, Klein and BesslerMannuzza et al, 1993; Reference Rasmussen and GillbergRasmussen & Gillberg, 2000). Comorbid illness makes the diagnosis more difficult (Reference Murphy and BarkleyMurphy & Barkley, 1996) and ADHD is often underdiagnosed in adults (Reference LambergLamberg, 2003).

One of the major difficulties in establishing the prevalence of adult ADHD is that continuity of care is lost during the transition from child and adolescent services to general adult services. This is evident from our survey. Only 300 (29.1%) respondents had transfer meetings. The comments of respondents indicated a widespread reluctance on the part of adult psychiatrists and general practitioners to prescribe stimulants to adults. There are very limited prevalence studies available and the exact prevalence is not known. In the USA, 5% of children have ADHD. Persistence into adulthood varies from 10 to 60%. Approximately 2% of US adults have ADHD, although this is not standardised worldwide (Reference Mannuzza, Kelin and MoultonMannuzza et al, 2003).

Currently in the UK there are limited reports on the prevalence of adult ADHD and it seems likely that adults with ADHD are under-recognised and undertreated. Their symptoms are distinct, although similar, to those of children with the disorder, but it is important to remember that adults are not just ‘grown-up’ children and may have entirely different presentations and problems. It can be confusing for clinicians who have little experience of screening for, or diagnosing adult ADHD. Self-report rating scales such as the Adult ADHD Self-Rating Scale (Reference Kessler, Adler and AmesKessler et al, 2005) and clinician-administered scales may be a helpful starting point, although they cannot replace an extensive clinical history and knowing when to refer the patient to a healthcare professional with experience of adult ADHD.

It is important to remember that adult ADHD remains a clinical diagnosis. This postal survey reveals the increasing demand and need for services and resources to treat adult ADHD. A substantial number of consultants have asked for funding and resources to treat this group of patients. Unfortunately they end up with no support from their trusts. More research needs to be done to establish the prevalence of ADHD in the adult population. The consultants who responded to this survey have expressed very great interest in this topic; one consultant commented ‘we need guidelines to assess and treat adult ADHD’. The survey clearly describes a need for a nation-wide service for adult ADHD. National guidance regarding the diagnosis and treatment of adults with ADHD would be a welcome development and should perhaps be addressed by the National Institute for Health and Clinical Excellence (NICE).

In conclusion, this survey highlights the importance of adult ADHD. There is clear indication from the survey that the prevalence of adult ADHD in England and Wales is likely to be high. More robust research is needed to find its exact prevalence.

Declaration of interest

Postal expenses were paid by Eli Lilly.