Diagnosis and management of attention-deficit hyperactivity disorder in children and adults with and without learning disability

AIMS AND METHOD

Anecdotal evidence suggests that attention-deficit hyperactivitydisorder (ADHD) is underdiagnosed in adults and people of allages with learning disability. This study examines the clinicalpractice of Irish consultant psychiatrists when assessing andtreating symptoms of ADHD in children and adults with and withouta learning disability. A postal questionnaire was sent to 302consultant psychiatrists working in Ireland.

RESULTS

Ninety-seven consultants (32%) responded, 62 working in generaladult psychiatry, 23 in child and adolescent psychiatry and12 in learning disability. Overall, respondents were more confidentabout making a diagnosis of ADHD in people without a learningdisability. Those working with children were significantlymore confident in diagnosing and treating ADHD than those workingwith adults, irrespective of whether the patient had a learning disability.

CLINICAL IMPLICATIONS

There is general agreement that symptoms of ADHD exist in childrenand adults both with and without a learning disability. Itis likely that ADHD may be undertreated in patients with learningdisability, especially in the adult population.

Introduction

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Introduction

Attention-deficit hyperactivity disorder (ADHD) is a heterogeneous constellation of complex neurodevelopmental problems ratherthan a single disorder (Zwi et al, 2000; Rowland et al, 2002).Studies have shown a higher prevalence of ADHD in children withlearning disability (Handen et al, 1994; Dekker & Koot, 2003).There is growing evidence that ADHD can be successfully treatedin children with learning disability (Handen et al, 1999; Barkley et al, 2002; Pearson et al, 2003) but it is very difficult to make a diagnosisin these children because of ‘diagnostic overshadowing’ (Reiss & Szyszko, 1983; White et al, 1995; Jopp & Keys, 2001; Mason & Scior, 2004).

Although the prevalence of ADHD in adults is not known (Schaffer, 1994)there is a growing consensus that ADHD continues into adulthood (Barkley, 1990; Toone et al, 1999; Fitzgerald, 2001; Willoughby, 2003).It seems logical that this disorder would present in adultswith a learning disability, and possibly to a greater extentthan in adults without such disability (Fox & Wade, 1998),but there are diagnostic difficulties with the current classificationsystem, particularly in making the diagnosis in adults andthose with learning disability (Murphy & Barkley, 1996;Seager & O’Brien, 2003).

The literature has shown that treatment of ADHD not only improvesabnormal behaviour but also self-esteem, cognition, and socialand family function, and that response can vary in differentage-groups and with certain comorbid conditions (Wender, 1995; Findling et al, 1996; Wilens et al, 1996). However, studiesindicate that less than half of those with the disorder are receiving treatment (Barkley et al, 2002; Dekker & Koot, 2003).

This study was carried out to assess the practice of Irish psychiatristsin relation to the diagnosis of ADHD. We postulated that thediagnosis of ADHD is generally overlooked in adults and inpatients with learning disabilities.

Method

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Method

Consultant psychiatrists were selected for this survey as weconsidered that their responses would reflect the current overallclinical practice in diagnosing and treating ADHD in Ireland.

An anonymous postal questionnaire was prepared specificallyfor this survey. An explanatory letter, a questionnaire relatingto either children or adults and a prepaid envelope were sentto all 302 consultant psychiatrists listed in the Irish MedicalDirectory (Irish Medical Services, 2003). Of these, 250 workedwith adults, 36 with children and adolescents, and 16 withpatients with a learning disability. Four weeks later a reminderletter was sent with further copies of the same questionnaires.

The questionnaire was designed to establish whether consultant psychiatrists believe that ADHD exists, what assessment methodsthey use and what treatments they use when working with childrenand adults both with and without learning disability. The questionnairealso requested demographics and examined levels of confidencein making the diagnosis of ADHD using a visual analogue scale;respondents were asked to indicate the frequency with which they included symptoms taken from DSM-IV criteria (American Psychiatric Association, 1994)using the following options: ‘never’, ‘sometimes’,‘often’, ‘always’. They were also askedto rank these symptoms in the order they considered the most important for making a diagnosis of ADHD. The questionnairealso included general questions concerning the respondents’understanding of ADHD and its assessment and treatment. Finally,participants were asked to add any other symptoms which theyregarded as important for the diagnosis of ADHD.

The Statistical Package for the Social Sciences version 10.1for Windows was used for data analysis.

Results

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Results

Although only 58 consultants responded initially (19%), 97 responseswere received in total after the reminder (32%). In total,25% (n=62) of the general adult and 64% (n=23) of the childand adolescent psychiatrists responded, and 67% (n=12) of thoseworking with learning disability.

All respondents were asked whether ADHD ‘occurred’in children, adults and in those with learning disability (Table 1).

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Table 1. Respondents’ views on the existence of attention-deficit hyperactivity disorder in children, adults and those with learning disability

Ranking and presentation
Ranking of symptoms of ADHD in children and adults both withand without learning disability was also examined using a Mann-Whitneyanalysis. Only one symptom ‘Often fidgets with handsor feet’ was ranked as significant only in patients withoutlearning disability. Consultants in adult psychiatry consideredfidgeting less important for a diagnosis in those without learningdisability than consultants in child psychiatry.

${chi}$ ² analysis revealed that the following six symptoms were seensignificantly more often by those working with children withoutlearning disabilities than by consultants working with adults:‘often fidgets with hands or feet’; ‘hasdifficulties engaging in leisure activities quietly’;‘is often on the go or acts as if driven by a motor’;‘blurts out answers before questions are completed’; ‘often interrupts or intrudes on others’; ‘doesn’t seem to listen when spoken to directly’.

Confidence in making a diagnosis
A two-way analysis of variance (ANOVA) was used to assess consultants’confidence in making a diagnosis of ADHD in adults and childrenwith and without learning disability. The dependent variablewas self-rated confidence (possible range 0–100). Theindependent variables were children/adults (non-repeated) andwith/without intellectual disability (repeated). Groups weredefined as adults and children and our population as with andwithout learning disability. No interaction was found betweengroup and population. However, the main effect for group wassignificant (F_obs=18.732, d.f.=1, 57, P<0.05).

Examinaiton of the means suggested that consultants workingwith children were more confident at making a diagnosis inpatients with and without learning disability than the consultantsworking with adults. The main effect for population was alsosignificant (F_obs=32.661, d.f.=1, 57, P<0.05), with themean scores suggesting that consultants were more confidentabout making a diagnosis of ADHD in patients without learning disability.

Methods of diagnosis
Respondents were asked in an open-ended question to specifywhich methods they used for diagnosing ADHD. The most commonanswers were:

clinical interview using diagnostic criteria from DSM-IV orICD-10
mental state examination
collateral history froma relative/carer/teacher
classroom observation
the Connersrating scales for parents and teachers
specialised psychologicalassessment
continuous performance test
refer to a specialist
occupational therapy assessment
work history.

Treatments
The most frequently used medications were methylphenidate and dexamphetamine. Other medication included carbamezepine, moodstabilisers, clomipramine, venlafaxine, psychotropics, imipramineand zopiclone. Other treatments included psychoeducation, cognitive-behaviouraltherapy, social skills training and occupational therapy. Acombination of stimulant medication and behaviour managementand Parents Plus programmes was also reported to be effective.

Discussion

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Discussion

The aim of this study was to establish whether consultant psychiatrists believe that ADHD exists, and what assessment methods and treatmentsthey use when working with children and adults both with andwithout learning disability. Most respondents reported observingsymptoms of ADHD in both children and adults with a learningdisability (n=77, 79%). However, certain symptoms were seenmore often by consultants working with children without learningdisability than those working with adults and significant differences were reported.

Consultants might be more confident about making a diagnosisof ADHD in patients without learning disability because of‘diagnostic overshadowing’ in the latter group (Reiss & Szyszko, 1983; White et al, 1995; Jopp & Keys, 2001; Mason & Scior, 2004). This is a well-described problemin the diagnosis of psychiatric conditions in people with learningdisabilities. It is of concern that despite indications thatADHD is more common in people with learning disabilities (Seagar& O’Brien, 2003) the diagnosis was not generallyconsidered in this group by those we surveyed.

It is interesting that the child psychiatrists were significantlymore confident in diagnosing ADHD in patients with and withoutlearning disability than those working with adults; this mayreflect the historical emphasis on this condition as beinga diagnosis of childhood and suggests the need for trainingof general psychiatrists (Royal College of Psychiatrists, 1998, 2004).

A limitation of this study is the poor response rate from certaingroups. Only 25% (n=80) of general adult psychiatrists completedthe questionnaire compared with 64% (n=23) of child and adolescentpsychiatrists and 75% (n=12) of consultants working with learningdisability. The overall response rate was 32% (n=97). Thisstudy reflects only the practice of one discipline; the practicesof other disciplines (e.g. psychology) were not examined. However, in Ireland the assessment and treatment of ADHD is usuallycarried out by multidisciplinary teams led by a consultantpsychiatrist and we believe that our results are a fair representationof current practice in Ireland.

Conclusion

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Conclusion

Our study shows that psychiatrists are less confident aboutmaking the diagnosis of ADHD in patients with learning disability,especially adults. Hence the diagnosis may go undetected witha resultant lack of appropriate treatment which may furthercompound existing impairments.

We believe that it would be useful to produce two consensusstatements regarding the assessment and treatment of ADHD:one in relation to adults and one in relation to patients ofall ages with learning disabilities. We will be recommendingto the relevant faculties of our College that groups be establishedto produce such consensus statements.

References

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