Dual disability

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CHAPTER 19 Dual disability

Dual disability refers to the coexistence of an intellectual disability (ID) or autism with mental health problems. Both ID and autism are classified as developmental disorders and require evidence of their presence in the first 18 years of life for a diagnosis to be made. However, the manifestations of these disorders extend into adulthood and the field of dual disability is concerned with the mental health of adults with either ID or autism. The need for this speciality arises because the presence of a developmental disorder both increases the risk of comorbid mental disorders, as well as complicates their assessment and management.

This chapter provides a brief overview of ID and of autism, before concentrating on dual disability.

Intellectual disability (ID)

The concept of an ID is that some people have difficulty in caring for themselves due to deficits in intelligence. The current DSM–IVTR diagnostic uses the term ‘mental retardation’. The criteria are shown in Box 19.1.

Population surveys usually find that about 2% of the population have an ID. People with severe ID are more likely to be identified early in life and are more likely to have an identifiable aetiology. Below the age of 6, the diagnosis is based on delay in achieving developmental milestones. Those with less severe ID may not be identified until they start school, when poor academic performance becomes evident. Some may not be identified until secondary school and may present with oppositional behaviours and truancy due to their inability to meet the demands placed on them. The diagnosis is confirmed by demonstrating the IQ and functional deficits. At any age it is important to exclude medical problems that may be contributing to impaired intellectual function (e.g. hypothyroidism).

Aetiology

There are over 300 identified causes of ID and more are being identified as technology becomes more advanced, particularly in the field of genetics. In clinical populations the cause will be identified in about 10–15% of cases, but with more intensive investigation it is possible to determine the aetiology in up to a third of cases. Understanding aetiology is useful for the following purposes:

in the development of preventative strategies

in predicting the health needs of people with specific syndromes, including targeted screening and intervention programs, and

in understanding certain behavioural patterns and the development of particular psychiatric disorders that are associated with specific syndromes.

Management

The underpinning philosophy of management is to assist people with an ID to lead as normal lives as possible. This means that the role of staff is to attempt to compensate for the functions that the person cannot complete independently. This can range from full assistance with dressing, toileting and eating in those with a severe ID, to occasional help with issues such as budgeting or a weekly shop for a person with a mild ID.

Many people with an ID live with their families. Those accommodated by services usually live in small groups of four to six people in residential houses, although some live independently and others remain in institutional settings. There is an expectation that whenever possible people with an ID should access the same facilities as the rest of the population, including schools, recreational, health and social services.

Autism and autism spectrum disorders

In the 1940s, Kanner initially described autism as a condition characterised by lack of verbal development, significant cognitive impairment, and a characteristic lack of interest in interacting with other people. Over time, the concept of a spectrum of autistic disorders has evolved, referring to a group of disorders with impairments of varying severity in three major areas, namely social interaction, communicative functioning and imagination.

These three functional deficits are referred to as the triad of impairments and can occur across a range of IQ scores. DSM–IVTR criteria are listed in Box 19.2.

BOX 19.2 DSM–IVTR criteria for autism (synopsis)

DSM–IVTR criteria are:

A. a total of six (or more) items from (1), (2) and (3), with at least two from (1), and one each from (2) and (3):

(1) qualitative impairment in social interaction, as manifested by at least two of the following:

(a) marked impairment in the use of multiple nonverbal behaviours such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction

(b) failure to develop peer relationships appropriate to developmental level

(c) a lack of spontaneous seeking to share enjoyment, interests or achievements with other people (e.g. by a lack of showing, bringing, or pointing out objects of interest), and

(d) lack of social or emotional reciprocity

(2) qualitative impairments in communication as manifested by at least one of the following:

(a) delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)

(b) in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others

(d) lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level

(3) restricted repetitive and stereotyped patterns of behaviour, interests and activities, as manifested by at least two of the following:

(a) preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal in either intensity or focus

(b) apparently inflexible adherence to specific, non-functional routines or rituals

(c) stereotyped and repetitive motor mannerisms (e.g. hand or finger flapping or twisting, or complex whole-body movements), and

(d) persistent preoccupation with parts of objects

B. delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (1) social interaction, (2) language as used in social communication, or (3) symbolic or imaginative play, and

C. disturbance is not better accounted for by Rett’s disorder or childhood disintegrative disorder.

In DSM–IVTR, the term pervasive developmental disorders (PDD) is used as the overarching term that covers the autistic spectrum disorders. This group includes five specified conditions, as shown in Box 19.3. See also Chapter 16 for a comparison between autism and Asperger’s disorder.

BOX 19.3 Autism spectrum disorders/pervasive developmental disorders (PDD)

• Autistic disorder is associated with a moderate to severe range of communication, socialisation and behaviour problems (see Box 19.2).

• Asperger’s disorder is a developmental disorder characterised by a lack of social skills, difficulty with social relationships, poor coordination and poor concentration, and a restricted range of interests; in contrast to autism, however, intelligence is normal and language skills in the areas of vocabulary and grammar are adequate.

• In Rett’s disorder, development proceeds normally for the first 6–18 months followed by a regression or loss of abilities. Characteristic repetitive ‘hand-washing-like’ movements may be the clinical give-away. This is an X-linked genetic mutation. It is lethal for males, who die in utero or soon after birth. Females may live to 40 years or more. Although people with this disorder have autistic features, there is debate about whether it should be classified as a PDD due to its clear-cut genetic aetiology.

• Childhood disintegrative disorder is extremely rare, and is characterised by regression in multiple areas of mental functioning following a period of at least 2 years of apparently normal development.

• Pervasive developmental disorder not otherwise specified is a term used when a person either does not fully meet the criteria to diagnose any of the four other subtypes of PDD, or does not have the degree of impairment required for their diagnosis.

The earliest epidemiological studies used Kanner’s very narrow criteria and found a prevalence rate for autism of around 0.05%. Much higher rates (around 1%) have been recorded using current diagnostic criteria for autistic spectrum disorders. The diagnosis is a clinical one and consists of gathering evidence of impairments in the triad of domains. The manifestations of these deficits are broadly covered in the diagnostic criteria (see Box 19.1 above), but can present in many different ways depending on age, sex, IQ, personality and situational context. The more severe the autism, the earlier the diagnosis; the more subtle variations may never be formally identified.

In addition to the classical triad, there are some other features that are common but not essential for the diagnosis. These include odd responses to sensory stimuli, including both hypersensitivity (e.g. extremely good hearing) and hyposensitivity (e.g. a very high pain threshold), poor motor coordination, over or under activity, and abnormalities of mood and of biological functions (e.g. eating, drinking and sleeping). Physical disabilities such as epilepsy and sensory impairments are common.

Aetiology

A range of factors have been implicated in causing autistic spectrum disorders. Genetic factors seem to predominate, although no simple pattern of inheritance has been identified and there are thought to be a range of genes that contribute to risk. Some specific genetic disorders are also associated with a higher risk of developing autism; these include fragile X syndrome.

Management

There is no known cure for autism, but appropriate management can ameliorate the impact. There is an emphasis on early intervention focusing on building communication skills using an educational approach. Operant-based behavioural techniques can enhance basic learning skills. Less conventional medical approaches include specific diets, supplements and medications, although there is no consistent evidence for any effect on the core features of autism. The outcome of any approach depends on the needs of the individual, which vary greatly, and on the appropriate application of the intervention itself.

Comorbidity and developmental disorders

Comorbidity is seen both between the developmental disorders themselves, as well as with other psychiatric disorders. Thus, around 20% of people with an ID have autism, while about 70% of people with autism have an ID. Around a third of people with developmental disorders have a comorbid mental disorder, with the risk increasing with the more severe levels of disability. The higher rates of comorbidity are thought to be due to exposure to risk factors, encompassing those factors shown in Box 19.4.

BOX 19.4 Factors underpinning comorbidity between ID and psychiatric symptoms

Biological factors

• Some genetic syndromes are linked both with ID and psychiatric illness (e.g. Down syndrome and dementia; fragile X and attention deficit hyperactivity disorder (ADHD)).

• Brain damage associated with an ID may give rise to problems of arousal, and difficulties in emotion regulation that can present as a psychiatric disorder.

• Certain genes lead to an ID and contribute to behaviour, and can be associated with specific behavioural problems called behavioural phenotypes (e.g. Lesch-Nyan syndrome and severe self-harming behaviour).

• People with an ID often have problems with hearing and vision, which is associated with increased risk for psychotic illnesses.

• Epilepsy occurs in 20% of people with an ID and is associated with depression and psychotic illnesses.

• Up to 30% of people with an ID are prescribed psychotropic medication which can have a number of behavioural and cognitive side effects.

Psychological factors

• People with an ID may be less able to develop effective coping strategies to deal with life stressors.

• People with an ID experience higher rates of stressful life events that are not explained to them (such as bereavement).

• Many people with developmental disorders have been teased and insulted from an early age and suffer from the effects of stigma and labelling.

• Low self-esteem and self-image may result from having an ID.

• Lack of verbal skills may mean inability to tell carers about problems and to make use of advice.

• Both psychiatric and physical symptoms may be modified by the presence of an ID, making their recognition and treatment less likely.

Assessment issues

There are a number of issues that complicate assessment of the person with a dual disability. These may be considered in terms of the diagnostic process itself, as well as in terms of the classification of these disorders.

Process issues

People with developmental disorders are often brought to treatment by carers and it can be they, rather than the patient, who is experiencing the distress.

Psychiatric symptoms may be attributed to the ID itself; this is called diagnostic overshadowing. It must be remembered that the only ‘symptoms’ of ID are deficits in intelligence and functional impairment.

Psychiatric illness commonly presents with difficult behaviour and is treated as a behavioural problem.

Concrete thinking, an inability to understand abstract concepts such as emotions or time, and poor communication skills can lead to difficulties in understanding the person’s internal experiences.

The impoverished social and life experiences can lead to the unsophisticated presentation of symptoms that are then not recognised (psychosocial masking).

Stress-induced disruption of information processing can present as bizarre behaviour and thought disorder (cognitive disintegration).

People with a severe ID have a limited range of responses and illness can present as a change in the frequency of certain behaviours that may be difficult to recognise as the manifestation of a psychiatric illness.

Stigma means many people with an ID try to appear ‘normal’ and symptoms may be denied.

People with an ID are suggestible and may not provide accurate information.

Diagnostic and classification issues

People with developmental disorders were largely excluded from the research used in the development of modern classification systems. This has given rise to the following problems:

People with an ID may not have developed the ability to experience the normal range of thoughts and emotions required to meet diagnostic thresholds.

Behavioural presentations of psychiatric illness have not been operationalised.

Some behaviours that may be troublesome in some people with developmental disorders have not been included in the classifications for mental illness (e.g. faecal smearing, wandering, shouting or undressing).

Some specific causes of an ID are associated with certain behaviours that have not been accounted for in the classification system (e.g. the overeating evident in Prader-Willi syndrome).

The types of problem presented do not fit neatly into a medical classification system and may be due to social factors such as changes in staff at the residential units or physical factors such as pain.

Psychiatric disorder may present in an altered form such as regression and loss of skills.

To account for these difficulties, the assessment process needs to be modified. It is important to determine who the main stakeholders are, as they may have different perceptions as to what constitutes the reason for assessment and treatment. There is increased reliance on observation and collateral history and a large part of the work often involves reviewing previous reports and file notes. It is important to establish the person’s best level of function, as this forms a point of comparison to judge the impact of any illness. The ability of the person to understand and report on their internal mental state needs to be assessed and the mental state examination modified accordingly. It is important to assess cognitive, emotional, physical and social developmental levels, as problems can arise from unrealistic expectations or mismatches between levels. Box 19.5 provides some clinical tips in the assessment of dual disability.

BOX 19.5 Clinical tips in the assessment of people with dual disability

• The assessment process is prolonged and cannot be completed within the usual hour session. It is important to allow adequate time, and often assessments consist of many interviews over several weeks.

• Beware of excessive compliance and scripted answers as people with an ID have often been interviewed many times and may just want to say the ‘right’ thing.

• Do not mistake self-talk for hallucinations or imaginary friends for delusions. This can be normal depending on the person’s developmental level.

• Good interview technique is crucial, as unlike the normal population this group will need guidance and support to tell their story and it is important to avoid leading questions (‘Were you feeling depressed?’) or multiple questions (‘How are you sleeping and eating?’).

• People with developmental disorders may have difficulty in answering open-ended questions (‘How are you feeling?’). Multiple-choice questions may have to be used (‘Are you feeling sad or happy?’). The answers should be cross-checked by asking the question in different ways and reversing the order of choices (‘Are you feeling good or bad?’).

• People with developmental disorders may have difficulties with abstract concepts, including time. It is sometimes useful to use anchor events (‘How were you feeling at Christmas?’). They may also have difficulty in putting events in the correct time sequence to make a coherent history and you may have to make the links for them.

• Seeing the person in their own environment usually gives a much more accurate picture of how they are, as much behaviour is specific to a situation or environment.

• The person’s appearance is more a reflection of the quality of care they receive, than a measure of their ability.

• It may not be possible to interview people with severe developmental disorders, although they may be engaged in activities such as going for a walk, drawing or playing a game, and this can provide useful information about their ability to interact with others.

CASE EXAMPLES: dual disability

A 21-year-old man with an IQ of 40 lived with his Italian Catholic family. He had started to rub his erect penis against other people, irrespective of age or gender. The possibility of a manic illness was considered, but the problem was thought to be because he had never had any sex education nor did he have any outlets to express his sexuality as his family did not think this was appropriate due to his intellectual impairment. In this case, his physical development was out of synchrony with his cognitive level.

A 24-year-old man with a mild ID and cerebral palsy became increasingly agitated over a period of months and lost a considerable amount of weight before making several serious suicide attempts. He complained of hearing the voice of a man telling him to do things. He was diagnosed with depression and treated with electroconvulsive therapy (ECT), making some improvement. Some weeks later he was able to disclose to his case manager that he had been sexually abused over a period of months at his day placement by his key worker who had also been telling him what to do and say. The diagnosis was revised to post-traumatic stress disorder (PTSD).

A 32-year-old woman with a mild ID had not left her room for several months and had been spending all her time lying on her bed. She had attracted a previous diagnosis of borderline personality disorder on the basis of aggressive behaviour and transient paranoia and hallucinations. On review, her parents reported a much wider range of psychotic symptoms that they had attributed to her ID. Her diagnosis was revised to schizophrenia and with appropriate treatment she was able to return to her day placement.

Specific psychiatric disorders

In people with an ID, comorbid disorders are well recognised in research settings, but often underreported and undiagnosed in clinical practice. Specific clinical scenarios include those described below.

Dementia and delirium

People with an ID are more likely to develop delirium in response to factors affecting brain function, such as infection, trauma, and illicit and prescribed drugs. People with Down syndrome are at very high risk of developing Alzheimer’s dementia and from age 40 onwards almost all will have pathological changes (although only a third will have clinical signs). The rest of the ID population seem to dement in the same way to the normal population, although it may be evident at a younger age due to the lower cognitive reserves. Problems can occur in making the diagnosis if the level of premorbid cognitive function is unknown.

Schizophrenia

Developmental disorders are risk factors for the development of schizophrenia and herald a poorer prognosis. Schizophrenia occurs at high rates in people with an ID (2–3%). The symptom profile in people with an ID is similar to that described in Chapter 5, but the disorder can present with aggression, disturbed behaviour or poor self-care.

Negative symptoms can exacerbate skill loss and cognitive changes can impair the ability to learn new skills. Schizophrenia cannot be reliably diagnosed in people with an IQ lower than about 50.

Mood disorders

Depression has a high prevalence in people with an ID. It may present with classical features such as tearfulness, lack of interest, social withdrawal and psychomotor retardation. However, some patients present with aggression, acting out or self-harming behaviour, or simply a loss of skills and social withdrawal. Mania presents with an increase in activity, intrusive behaviour, destructiveness, irritability and sometimes self-abusive behaviour.

Anxiety disorders

As in the normal population, anxiety may present with repetitive worrying thoughts, fear and, in extreme instances, panic. However, people with an ID may have difficulty communicating their fears, and physiological manifestations such as flushing, sweating, pallor, tremor, hyperventilation and insomnia can be useful clues. Avoidance is a common behavioural manifestation of anxiety. Relatively greater emphasis is placed on phenomena such as agitation, screaming, crying, withdrawal, regressive/clingy behaviour or freezing.

Personality disorders

Many patients with an ID have a background of abuse, neglect, poor parenting, inadequate education, and poor social and coping skills, coupled with a low tolerance of frustration with impaired impulse control. A personality disorder can often present with a range of unacceptable behaviours such as aggression or inappropriate sexual activity, but is often labelled a behaviour disorder. The prevalence is thought to be about 20% among those with an ID.

Behaviour disorders

People with an ID can present with behaviours that can be dangerous to themselves or others and limit their opportunities to lead a normal life. The current term to describe these is challenging behaviours, although the term behaviours of concern is coming into vogue. In some cases these behaviours are secondary to an underlying illness, which may be medical or psychiatric, and it is important to exclude these before adopting a behavioural framework. A behavioural framework assumes the behaviour has a function for the individual. In this situation an intensive process is undertaken, to record the situations leading to the behaviour, and what happens afterwards. This information can be analysed with a view to understanding the underlying motivation; this is termed a functional (or applied) behavioural analysis. Interventions are based on helping the person to communicate and to learn skills that help them meet their needs, in addition to adjusting the environment to encourage appropriate behaviour.

Mental health in the severely disabled

This group often has multiple handicaps, including epilepsy, sensory deficits, and limited mobility and communication. They have a restricted range of responses, and the bulk of pathology consists of behaviour disorders, with an unclear relationship to other forms of psychiatric illness. Impulsive, explosive and sexually inappropriate behaviours are common. Repetitive stereotyped movements often occur and connections to obsessive-compulsive disorder and to schizophrenia have been suggested.

CASE EXAMPLES: manifestations of dual disability

A 40-year-old man with Down syndrome abruptly started running up to people and hitting them at the factory where he worked packing tins into boxes. Dementia was considered but there was no loss of skills. It was thought that he might be responding to hallucinations, but the behaviour was specific to his workplace. A behaviour analysis over several weeks revealed that the only time staff interacted with him was following an assault. It was established that since a new particularly disabled client had started at the workplace, staff had had significantly less time to interact with the patient. Increasing the staffing levels to deal with the new client resolved the issues.

A 20-year-old man with a moderate ID exhibited a deterioration in behaviour over a period of 6 months. He was pacing while mumbling ‘bad boy’, ‘don’t do that’ and ‘shush’, and engaging in severe self-harming behaviour by charging at walls and banging his head. As his mother had treatment-resistant schizophrenia, it was thought he had become psychotic and was responding to hallucinations. On assessment it was determined that he had autism and the self-talk was usual when he was agitated. On physical review it was noted that he had pus in his left ear. Otitis media was diagnosed and treated, after which his behaviour returned to base line.

A 60-year-old man with a mild ID was taken to the hospital emergency department after making suicidal threats. This was in the context of his having been evicted from his shared accommodation after he had attempted to set fire to the house using petrol. There was concern that he had a depressive illness. However, on review of his file it was evident that he had a long history of offences with repeated threats of suicide when confronted with the consequences of his actions. He met the criteria for antisocial personality disorder with significant borderline traits. It was recommended that he be charged with arson.

Management

There is little research specifically on the treatment of mental disorders in people with developmental disorders, and treatments broadly parallel those used in the rest of the population. However, a number of specific issues need to be borne in mind when articulating a treatment plan in those with a developmental disorder. One particular issue is that of consent to treatment. Although in common law an adult is presumed to have capacity to give or withhold consent until proved otherwise, developmental disorders impair some of the abilities required for decision making, leading to a lack of capacity. Although mental health Acts usually provide a legal framework to enable individuals who lack capacity to be treated, there is often no equivalent power in disability legislation. In general, it would be appropriate to use mental health legislation when the person is being treated for a mental illness and to use guardianship powers for other decisions involving health and lifestyle problems.

Pharmacotherapy in people with a developmental disorder should be directed at specific diagnostic hypotheses using the same principles as for the normal population. There is some evidence that drugs take longer to work and that lower doses are required in those with developmental disorders. Objective measures of response and side effects should be implemented.

Psychological treatments have general applicability in the developmental disorders population, but modifications may be required to ensure the individual can understand the intent and process. Behavioural treatments have ascendency, though cognitive approaches can be used in those of higher intellectual functioning. People with an ID often take longer to respond to psychological treatments, and may need lots of real-life practice to understand some of the techniques. This often works best if the person’s social network is involved in the treatment program.

Social interventions are a critical component of the comprehensive care of the individual with a developmental disorder. These encompass provision of pleasant living situations, opportunities for meaningful recreational and vocational activities, and opportunities to develop satisfying relationships. Regrettably, these aims are often difficult to achieve.

It usually is not possible for one service provider to meet the complex needs of this population and there are often several services involved with a multitude of different professionals and carers. Table 19.1 provides a guide to the different activities undertaken by the more commonly involved service providers.

TABLE 19.1 Roles of members of the multidisciplinary and extended team in the management of the person with dual disability

Profession/position	Role
Disability case manager	Identify the person’s needs and broker other services to provide these. Sometimes this role itself is undertaken by another agency
Mental health case manager	Monitoring and delivering therapeutic interventions
Psychiatrist	Assessment and treatment of mental disorders
General practitioner	Provision of general healthcare and screening
Psychologist	Assessment of IQ and neuropsychological function
Behaviour intervention and support practitioner	Undertake a functional behaviour analysis with the aim of developing a behaviour management plan
Carers and families	Carers may be paid or unpaid family members. They will often assist the person with day-to-day function, as well as implement strategies devised with the assistance of other professionals (e.g. administer medication and behaviour interventions)
Guardian	A guardian is often needed to make decisions on behalf of the person, including consenting to treatment. They may be formally appointed through a court process or a family member may often informally adopt this role
Other	There are a range of other people with significant roles who may be involved, including the house supervisor or manager in shared accommodation facilities, house staff, teachers, one-to-one workers (often employed to supervise the person for several hours at a time), counsellors, employers, trainers/educators at day placements and also peers with whom they may have significant relationships