S. Deb, M.Thomas & C. Bright. Abstract

Transcription

1 506 Journal of Intellectual Disability Research VOLUME 45 PART 6 pp DECEMBER 2001 Mental disorder in adults with intellectual disability. 2:The rate of behaviour disorders among a community-based population aged between 16 and 64 years S. Deb, M.Thomas & C. Bright Division of Psychological Medicine, University of Wales College of Medicine, Cardiff, UK Abstract Despite the difficulty of defining behaviour disorder, most previous studies have reported a high rate of behaviour disorders in people with intellectual disability (ID). The aim of the present study was to establish the overall rate and types of behaviour disorders in a population-based sample of adults with ID. The other aim was to explore the possible risk factors that are associated with the overall rate as well as different types of behaviour disorders. One hundred and one adults with ID aged between 16 and 64 years were randomly selected from a sample of 246 such adults, i.e. those who were known to the Vale of Glamorgan Social Services Department in South Wales, UK. Thirteen behaviour disorders were rated according to the Disability Assessment Schedule. Background data on subjects were also collected, and were subsequently analysed to assess the relationship between different risk factors and behaviour disorders. Sixty-one subjects (60.4%) had Correspondence: Dr Shoumitro Deb, Division of Psychological Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK ( Deb@Cardiff.ac.uk). at least one behaviour disorder of any severity or frequency. Twenty-three per cent of subjects showed aggression, 24% self-injurious behaviour, 36% temper tantrum, 26% overactivity, 29% screaming, 38% attention-seeking behaviour, 20% objectionable habits, 18% night-time disturbance and 12% of subjects showed destructiveness. Statistically significant associations were seen between the rate of overall behaviour disorder and the use of psychotropic medication, and between family and group home residence. The rate of aggression was significantly associated with the use of psychotropic medication. The rate of self-injurious behaviour was significantly associated with the severity of ID, female gender and poor communication abilities. The rate of temper tantrum was significantly associated with the use of psychotropic medication. Twenty-four subjects showed severe or frequent aggression, destructiveness, self-injury or temper tantrum, and 11 individuals showed real challenging behaviours. Severe behaviour problems were significantly associated with female gender, severity of ID, the presence of a history of epilepsy and attendance at day activities. Keywords behaviour disorder, intellectual disability, population-based adults, risk factors 2001 Blackwell Science Ltd

2 507 Introduction Behaviour disorders are common among people with intellectual disability (ID). However, it is difficult to define these problems, particularly since they depend on the perception of the people who are at the receiving end of these behaviours. In general, these include aggression, destructiveness, self-injurious behaviour, temper tantrum, overactivity, screaming/shouting, scattering objects around, wandering, night-time disturbance, objectionable personal habits, antisocial behaviour, sexual delinquency, and attention-seeking behaviour. In a population-based cohort of 2202 adults with ID from Leicestershire, UK, Smith et al. (1996) reported behaviour disorder in about 64% of their study population. In an older study of case registers of individuals known to services in New York State, USA, Jacobsen & Janicki (1985) found behaviour disorder among 57 60% of these individuals. Koller et al. (1983) reported behaviour disorder among 59% of a population-based sample of subjects with ID. Deb & Hunter (1991a) found behaviour disorders among 55% of 300 adults with ID, half of whom had epilepsy. The above authors did not find any statistically significant difference in the rate of behaviour disorders between subjects with and without epilepsy. In a community study, Harris (1993) reported aggression among 17.6% of subjects with ID. In a study of 2412 subjects with ID, Sigafoos et al. (1994) found that 11% showed aggressive behaviour, of whom 34% showed selfinjurious behaviour. The aims of the present study were to establish the overall rate and also the rate of different types of behaviour disorders in a population-based sample of adults with ID. The authors were also interested to assess the possible association between various risk factors and behaviour disorders. Subjects and methods Subject selection In the Vale of Glamorgan in South Wales, UK, the general population is approximately Approximately (63%) of these individuals are between the ages of 16 and 64 years. Some 246 (3.2 per 1000) adults in this age group with ID were known to the social services register. Out of these 246 subjects, 120 were randomly selected using a computer programme. One hundred and one (84%) of these 120 individuals were available for behavioural rating. Data collection A purpose-designed questionnaire was used to collect data from a face-to-face interview with the subjects and their carers, and in certain cases, key workers (in some cases, data were also corroborated from medical case notes) during an interview in subject s home setting. The information collected on subjects included their age, gender, cause of ID, level of ID, presence of any physical disability (e.g. deafness, visual problems or muscle weakness), presence of physical illness (e.g. asthma, diabetes or hypertension), history of epilepsy, detail of current medication, whether the subjects attended any day activity, level of speech (i.e. good normal conversation, can make sentences, can put a few words together or no speech), type of accommodation (i.e. family home, group home, live on their own or other accommodation). These data were analysed to assess for any association between these factors and behaviour disorder. All subjects and their carers were interviewed by a trained psychiatrist (M.T.) who, along with a psychiatric interview, rated these subjects on 13 different behaviour disorders according to the Disability Assessment Schedule (DAS; Holmes et al. 1982). The 13 behaviour disorders in the DAS were aggression, destructiveness, self-injurious behaviour, temper tantrum, overactivity, screaming/shouting, scattering objects aimlessly, wandering, night-time disturbance, objectionable personal habits, antisocial behaviour, sexual delinquency, and attentionseeking behaviour. Each behaviour was rated on a five-point ranking scale: (0) absent; (1) severe and frequent (more than three times per week); (2) less severe, but frequent; (3) severe, but less frequent; and (4) lesser management problem. For the purpose of the present study, the authors included only those behaviours as present in which the subjects scored between 1 and 3. They have also separately analysed data based on behaviours such as aggression, self-injurious behaviour and temper tantrums that had a score of either 1 or 2

3 508 (defined as severe behaviour disorder ), and those scored 1 only (behaviour both severe and frequent, defined as challenging behaviour ). Holmes et al. (1982) tested inter-rater, interobserver and test retest reliability of scores according to these 13 behaviour disorders and found them to be very high. Data analysis The rate of overall behaviour disorder and those of individual behaviour disorders were estimated along with their 95% confidence interval (CI). A stepwise logistic regression analysis of those factors that may affect the overall rate and type of behaviour disorders was also carried out. Results Description of the cohort The age range of the cohort was between 16 and 64 years (mean ± SD = 37.7 ± 13.5). There were 51 males and 50 females. Forty-eight subjects had mild, 42 moderate and 11 had severe ID. Thirty-six individuals were between 16 and 29 years of age, 31 between 30 and 45 years, and 34 were between 46 and 64 years of age. Sixty-three had good speech, 16 could put sentences together, 11 could put a few words together and 11 had no meaningful speech. In 32 cases, the cause of ID was known (e.g. Down s syndrome). Twenty-one patients had an associated physical disability and eight had a chronic physical illness. Seventy subjects attended some day activities. Forty-one individuals lived in a family home, 37 in a group home, seven on their own and 16 in other accommodations. In 25 cases, there was a history of epilepsy. Fifty subjects did not receive any medication, whereas 12 received antipsychotics, three antidepressants, 21 antiepileptics and 10 received other medication. In five cases, the medication history was not clear. Findings Altogether, 61 (60.4%) subjects showed behaviour disorder. Forty-four showed up to five behaviours together: nine showed one behaviour; 11, two behaviours; 12, three behaviours; eight, four behaviours; and four individuals, five behaviours. The rest Table 1 Rates of different types of behavioural disorders in two studies: (95% CI) ninety-five per cent confidence interval; and (c 2 ) chisquare test Present study (n = 101) Smith et al. (1996)* (n = 2202) 95% CI of Behavioural disorder Number percentage Number Percentage Aggression Destructiveness Self-injury Temper tantrum Overactivity Screaming/shouting Scatters objects Wandering Night-time disturbance Objectionable personal habits Antisocial behaviour Sexual delinquency Seeks attention * Numbers and percentages are calculated from the data in Smith et al. s (1996) Tables 1 and 2. c 2 = 6.70, d.f. = 1, P = c 2 = 8.12, d.f. = 1, P =

4 509 (n = 17) showed more than five behaviours together: two showed six behaviours; five, seven behaviours; five, eight behaviours; one, nine behaviours; three, 11 behaviours; and one individual showed 12 behaviours. Table 1 shows the rates with the 95% CIs of individual behaviour disorders in the current study cohort in comparison with those reported in the Smith et al. (1996) cohort. In Table 2, the present authors have presented the differential rates of overall behaviour disorder in different subgroups of the cohort. Since previous studies on behavioural problems concentrated primarily on severe problems, particularly aggression, destructiveness and self-injury (Quereshi & Alborz 1992; Emerson et al. 1997), the present authors have separately calculated their data primarily including these behaviours. Twenty-four subjects (23.8%) showed severe and/or frequent (more than three times a week) (score 1 or 2 ) aggression towards others or objects (destructiveness), or self (self-injurious behaviour) or tantrum (n = 6). The present authors have analysed separately the risk factors associated with these severe behaviour disorders and presented them in Table 3. In 11 subjects (10.9%), these behaviours were both severe and frequent (score 1 only) (tantrum in two subjects). These behaviours posed a challenge to the services and could be termed as challenging behaviours. In Table 4, the present authors have presented the differential rates of aggressive behaviour in different subgroups of the cohort. In Table 5, they have presented the differential rates of self-injurious behaviours in different subgroups of the cohort. Regression analysis of independent variables showed no statistically significant association of any of these factors with overactivity. However, there was a statistically significant association between temper tantrum and the use of psychotropic medication (50% of those who received antipsychotic medication showed temper tantrums, 100% of those who received antidepressants, 50% of those who received antiepileptic medication, 20% of those who received other medication and 28% of those who received no medication showed temper tantrums; c 2 = 10.42, P = 0.03, d.f. = 4). A statistically significant association was seen between the accommodation types (group home = 24%, family home = 7.5%, Table 2 Rates of overall behavioural disorders in different subgroups of the cohort with intellectual disability (ID): (c 2 ) chi-square test Behavioural disorders Subgroup Total number Number Percentage Gender Male Female Age group (years) Accommodation* Family home Group home Single Other Cause of ID Known Unknown Drugs** Neuroleptics Antidepressants Anti-epileptics Other None Epilepsy Present Absent Day activities Present Absent Level of ID Mild Moderate Severe Speech Good Sentences Words None Physical disability Present Absent Physical illness Present Absent Psychiatric illness (mild/moderate ID) Present Absent * c 2 = 8.07, d.f. = 3, P = ** c 2 = 14.02, d.f. = 4, P =

5 510 Table 3 Rates of overall severe behavioural disorders in different subgroups of the cohort with intellectual disability (ID): (c 2 ) chisquare test Severe behavioural disorders Subgroup Total number Number Percentage Gender* Male Female Age group (years) Accommodation Family home Group home Single Other Cause of ID Known Unknown Drugs Neuroleptics Antidepressants Anti-epileptics Other None Epilepsy*** Present Absent Day activities**** Present Absent Level of ID** Mild Moderate Severe Speech Good Sentences Words None Physical disability Present Absent Physical illness Present Absent Psychiatric illness (mild/moderate ID) Present Absent * c 2 = 3.7, d.f. = 1, P = ** c 2 = 6.54, d.f.= 2, P = *** c 2 = 4.83, d.f. = 1, P = **** c 2 = 7.42, d.f. = 1, P = Table 4 Rates of physical aggression in different subgroups of the cohort with intellectual disability (ID): (c 2 ) chi-square test Physical aggression Subgroup Total number Number Percentage Gender Male Female Age group (years) Accommodation Family home Group home Single Other Cause of ID Known Unknown Drugs* Antipsychotics Antidepressants Anti-epileptics Other None Epilepsy Present Absent Day activities Present Absent Level of ID Mild Moderate Severe Speech Good Sentences Words None Physical disability Present Absent Physical illness Present Absent Psychiatric illness (mild/moderate ID) Present Absent * c 2 = 10.78, d.f. = 1,4 P = 0.03.

6 511 Table 5 Rates of self-injurious behaviour in different subgroups of the cohort with intellectual disability (ID): (c 2 ) chi-square test Self-injurious behaviour Subgroup Total number Number Percentage single = 0% and other accommodations = 0%; P = 0.02) and destructiveness. For the purpose of comparison, the present authors have summarized the findings from the previous studies on the prevalence of behavioural problems and challenging behaviours in Table 6. Gender* Male Female Age group (years) Accommodation Family home Group home Single Other Cause of ID Known Unknown Drugs** Neuroleptics Antidepressants Anti-epileptics Other None Epilepsy Present Absent Day activities Present Absent Level of ID*** Mild Moderate Severe Speech** Good Sentences Words None Physical disability Present Absent Physical illness Present Absent Psychiatric illness (mild/moderate ID) Present Absent * c 2 = 7.89, d.f. = 1, P = ** c 2 = 13.67, d.f. = 3, P = *** c 2 = 16.18, d.f. = 2, P < Discussion Principal findings A high proportion (60.4%) of adults with ID showed at least one behaviour disorder of any severity or frequency. Certain factors such as the use of antipsychotic medication, attendance at any day activity, severity of ID and poor speech were significantly associated with different types of behaviour disorders. Severe behaviours were found among 18% of subjects in the form of aggression, destructiveness and self-injury, and 6% showed tantrum. The occurrence of severe behaviour disorders was significantly associated with the female gender, severity of ID, the presence of epilepsy and attendance at day activities. Strengths and weaknesses of the current study The present authors believe the particular strengths of this study are that it used a population-based sample, a face-to-face interview was conducted with subjects and their carers to gather information, the rating of behaviour disorders was done by a trained psychiatrist, a validated instrument that has been used widely before was used for behaviour ratings (i.e. DAS; Holmes et al. 1982), psychiatric diagnoses were made in the same population in which behaviour rating was done and a wide range of risk factors were analysed. However, definition of behaviour disorder remains difficult, and it depends on the perception of the observer/reporter of the behaviour, the timing and the setting. It is possible to achieve different prevalence figures of behaviour disorder by using different rating scales. The number of adults with ID known to the social services register was much lower than expected. This is not unusual for an administrative sample such as the present one, but it also means that a higher proportion of subjects with behaviour disorder are known to the service

7 512 Table 6 Prevalence studies of behaviour disorders in adults with intellectual disability (ID) Study Number Sample characteristics Prevalence Jacobson (1982) New York case register, 66% between 50% with mild ID 21 and 64 years of age (case record 55% with moderate ID study) 64% with severe ID 75% with profound ID (including delusions, hallucinations, depression and suicidal threats) Koller et al. (1983) 150 Population-based sample 59% of total cohort (post-school subjects) (children and post-school subjects) 52% with mild ID 56% with severe ID (any behaviour disorder) 18% of total cohort 17% with mild ID 14% with severe ID (severe behaviour disorders) Jacobsen. & Janicki (1985) New York case register, 60% with severe ID (profound/severe ID) approximately half in the 57% with profound ID community and one-third (any behaviour disorder) over 22 years of age Borthwick-Duffy (1994) California case register (all ages) 15.3% of over 21 years of age 7.6% with mild ID 12% with moderate ID 22% with severe ID 33% with profound ID (severe aggression, destructiveness and self-injury) Quereshi & Alborz (1992) Population-based case register 16.5% of total ID cohort 1.9 per general population (challenging behaviours) Smith et al. (1996) Population-based case register 64% of total cohort 17.6 per general population (any behaviour disorder) Emerson et al. (1997) Population-based case register 12% of total ID cohort 3.3 per general population (challenging behaviours) agencies. Therefore, the true rate of behaviour disorder in the population is likely to be lower than that found in the current study. Comparison with other studies The overall rate of behavioural problems in the present study was similar to that found by Smith et al. (1996), who used the same behaviour rating scale, although they had a higher proportion of patients with severe and profound ID in their cohort. Apart from the rates of overactivity and attention-seeking behaviour, the rates of different types of behaviour disorders found in the current study were similar to those found by Smith et al. (1996). The rate of attention-seeking behaviour

8 513 depends very much on staff s or carer s attitude to and perception of this behaviour. Emerson et al. (1997) and Quereshi & Alborz (1992) found severe challenging behaviours among 10 15% and 16.5% of their subjects with ID, respectively, particularly in the form of severe aggression, self-injury and destructiveness. The overall rate of severe challenging behaviour in the current study is comparable with these findings. In contrast with the findings of the current study, Emerson et al. (1997) found a predominance of males among the subjects with severe challenging behaviours (although there was an association between female gender and self-injurious behaviours). Like the current study, Emerson et al. (1997) found an association between severe challenging behaviour and the increasing severity of ID. However, they found aggression, temper tantrum and repetitive posturing more common among subjects with less severe ID, whereas selfinjury was more prevalent among those with more severe ID. In the current study,a similar trend was found among subjects who showed self-injury, but no such association was found between the severity of ID and either aggression or temper tantrums. The present authors did not find any significant association between the overall rate of behaviour problems (of any type and severity) and the presence of epilepsy. This is in line with some previous studies (Deb & Hunter 1991a; Deb & Joyce 1998). However, when the present authors compared the rate of severe behaviour problems (rating 1 or 2 on aggression, self-injury and tantrums) with the history of epilepsy, they found a significant association. Controversial evidence exists in the literature regarding a positive relationship between psychiatric illness and behaviour problems: whereas Deb & Hunter (1991b) found no positive correlation, Lauder et al. (1984) did. Behaviour disorder was present among 84.6% of those who had a psychiatric illness and 54.5% of those who did not. Psychiatric disorder was present among 20.8% of those who had behaviour disorder and 5.4% of those who did not. These differences were not statistically significant. It is worth noting that Moss et al. (2000) have recently reported an association between the increasing severity of challenging behaviour and an increased prevalence of psychiatric symptoms, most prominent being the depressive symptoms. They have also shown an association between the anxiety symptoms and the presence of self-injurious behaviour. Clinical implications The analysis of the risk factors has revealed some interesting findings. A significantly higher proportion of those who showed behaviour disorders lived in group homes compared with family homes and other accommodation. Although expected, this finding has obvious implications for service provision. The present authors also found a strong association between the use of psychotropic medication, including antipsychotics, antidepressants and antiepileptic medication, and the rate of behaviour disorder. It is difficult to establish the cause and effect relationship between the two. One may argue that this association is a reflection of an association between psychiatric illness and behaviour disorder. However, this association was not apparent when we compared ICD-10 psychiatric diagnosis with the use of medication (see Deb et al. 2001, pp ). This perhaps again highlights the issue of the use of antipsychotic medication in people with ID who show behaviour disorder in the absence of any detectable psychiatric illness (for review, see Deb & Weston 2000). There was a significant association between selfinjurious behaviour and female gender. Similar findings have been reported previously (Maisto et al. 1978; Maurice & Trudel 1982). Collacott et al. (1998) did not find an association between selfinjurious behaviour and gender, but like the present authors, found an association with developmental quotient. There is no equivalent diagnostic category in the ICD-10 for behaviour disorder, although, among children, conduct disorder is a valid diagnosis. The present authors found that the overall rate of mental disorder, including both behaviour disorder and functional psychiatric illness, was quite high in their study cohort (64%). This figure is comparable with many previous studies of prevalence of psychiatric illness among adults with ID in which behaviour disorder was included among the overall diagnosis of psychiatric illness (Corbett 1979; Lund 1985; Cooper 1997).

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