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PubMed2005

Material, psychosocial, and behavioural factors in the explanation of educational inequalities in mortality in The Netherlands.

STUDY OBJECTIVES: To assess the direct and indirect contributions of material, behavioural, and psychosocial factors to the explanation of educational inequalities in mortality simultaneously. DESIGN: Prospective observational study (1991-1998). SETTING: General population from south east Netherlands. PARTICIPANTS: 3979 men and women aged 15-74 years without severe chronic disease at baseline (1991). MAIN RESULTS: Material factors (type of health insurance, financial problems, and housing tenure), psychosocial factors (life events and external locus of control), and behavioural factors (smoking habits and physical activity) together reduced the relative risk of mortality of the lowest educated group from 2.57 (95%CI 1.43 to 4.64) to 1.01 (95%CI 0.50 to 2.03). Of these three groups of factors, material factors contributed most to the educational inequalities. Part of the contribution of material factors was via psychosocial factors and part via behavioural factors. Psychosocial factors contributed to educational inequalities, partly via behavioural factors. Behavioural and psychosocial factors contributed only marginally to the explanation independent of material factors. CONCLUSION: Educational inequalities in mortality were explained by material, psychosocial, and behavioural factors. Material factors contributed most to the explanation, partly via psychosocial and behavioural factors. Improving the material situation of lower educated people may substantially reduce educational inequalities in mortality, partly via the psychosocial and behavioural consequences of improved material circumstances.

Adult↗
PubMed1999

Social mobility and health related behaviours in young people.

STUDY OBJECTIVE: To assess the influences related to social mobility, particularly health related behaviours, as one potential explanation for the social class variation in health among adults. DESIGN: The study is based on questionnaire data from the Adolescent Health and Lifestyle Surveys of 1985, 1987, and 1989. SETTING: The whole of Finland. PARTICIPANTS: A representative sample of 8355 adolescents. The response rate was 79%. MEASUREMENT AND MAIN RESULTS: The relation between social mobility and health related behaviours among 16 and 18 year old young people was studied. The measure of social mobility was based on a combination of the social class of origin and achieved social position measured by the present educational status, educational attainment, and labour market position. Three mobility groups were constructed: the downwardly mobile, the upwardly mobile and the stable. Health related behaviours in an upwardly or downwardly mobile group were compared with a stable group from the same social class of origin by calculating relative risks (RR). RRs were assessed by calculating age and sex adjusted rate ratios approximating a Mantel-Haenszel estimate. In logistic regression analyses the independent effects of the social class of origin and the achieved social position were investigated. Most of the nine behaviours studied (smoking, alcohol use, heavy intoxication, coffee drinking, tooth brushing, consumption of sweets, lack of physical exercise, choice of bread spread, and consumption of milk) were related to the direction of mobility so that health compromising behaviours were more frequent among downwardly mobile and less frequent among upwardly mobile young people than their stable peers. Achieved social position proved to determine health related behaviours more strongly than class of origin, thus emphasising the way education facilitates both health values and behaviours as well as the future social position. CONCLUSIONS: The close relation between social mobility and health related behaviours is concluded to be a part of an explanation of social class differences in health observed among adults.

Adolescent↗
PubMed2004

Informal confidential voting interview methods and temporal changes in reported sexual risk behaviour for HIV transmission in sub-Saharan Africa.

OBJECTIVES: Reliable data on sexual behaviour trends are needed to evaluate HIV interventions in sub-Saharan Africa but are difficult to obtain due inter alia to social desirability bias. The objective of this paper is to assess whether the use of informal confidential voting interviews (ICVI) was associated with greater reporting of socially proscribed behavioural risk factors for HIV infection than were conventional interviewing methods. METHODS: Comparison of changes in reports of risk behaviours for HIV infection in ICVI versus face to face interviews (FTFIs) between the first two rounds of a large scale, longitudinal, population based survey in Manicaland, Zimbabwe. Examination of factors that could contribute to observed changes in the effect of ICVI, including temporal changes in response error and social desirability, and factors affecting statistical power to detect differences between methods-that is, reductions in the prevalence of risk behaviours and sample size. RESULTS: Enhanced reporting of HIV associated risk behaviours in ICVI interviews was not so apparent in the second round as in the first round of the survey, particularly for less frequently reported behaviours. Levels of reported HIV associated risk behaviour and sample sizes both declined between the two survey rounds. The level of response error was higher in ICVI interviews than in FTFI interviews but did not alter over time. CONCLUSION: ICVI interviews can reduce social desirability bias in data on HIV associated risk behaviours. The extent and direction of change in net reduction in bias over time remains uncertain and will depend on local circumstances.

Adult↗
PubMed1999

Evaluation of clomipramine as an adjunct to behavioural therapy in the treatment of separation-related problems in dogs.

Forty-nine dogs showing signs of separation-related problems were randomly assigned to one of three groups: group A (15 dogs) received a placebo twice daily; group B (17 dogs) received clomipramine at 0.5 to 1.0 mg/kg twice daily; and group C (17 dogs) received clomipramine at 1.0 to 2.0 mg/kg twice daily. All the dogs also received behavioural therapy. Their owners were required to complete questionnaires about their dog's behaviour initially, and one, four and eight weeks after the treatment with clomipramine began. Bipolar ratings scales were used to monitor the frequencies of 'general', 'attachment-related' and 'separation-related' behaviours. Kruskal-Wallis tests and Kendall Rank correlations were used to determine any initial differences between the treatment groups, and the association between the initial scores and behavioural changes after one week of treatment with clomipramine. Extended Mantel-Haenszel statistics were used to evaluate the effects of clomipramine treatment versus the placebo, and Page's test was used to assess the effectiveness of behavioural therapy on its own. There were no significant differences in the demographic characteristics of the owners of the dogs assigned to the three groups. The dogs differed slightly in age between groups, and the dogs in the two clomipramine-treated groups were reported as showing problems at a significantly earlier age than those in the placebo group. Clomipramine treatment had a sustained suppressive effect on the dogs' general activity levels, and a more modest suppressive effect on their attachment-related tendency to want much physical contact with their owners. The typical signs of separation-related behaviour problems were not significantly affected by treatment with clomipramine, but behavioural therapy on its own was highly effective in reducing behavioural problems.

Adult↗
PubMed2002

Aetiology of separation-related behaviour in domestic dogs.

A longitudinal study of seven litters of labrador retrievers and five litters of border collies from eight weeks to 18 months of age indicated that the majority showed some degree of potentially undesirable behaviour when separated from their owners. Its incidence was particularly high in the labrador retrievers, of which 13 of 23 showed separation-related behaviour for more than a month. Socially diverse environments experienced between six and 12 months of age were associated with a subsequent absence of separation-related behaviour. In a questionnaire survey of dog owners, separation-related behaviour was reported in 27 of 94 dogs, and a further 20 had shown the behaviour in the past. Male dogs were more likely to express separation-related behaviour currently, and females were more likely never to have displayed it. The prevalence of the behaviour was unaffected by whether the dog was pedigree or mixed breed, or whether it had been obtained from a breeder or from a rescue organisation. Combining the results of the two studies, the owners of only six of 75 dogs showing separation-related behaviour had sought assistance, and only two of the owners had sought help from veterinary surgeons.

Animals↗
PubMed2001

A two-locus model for experience-conditioned direction of paw usage in the mouse is suggested by dominant and recessive constitutive paw usage behaviours.

Left-right direction of paw usage in the mouse depends on the genotype and the directional nature of the test. There are two phenotypic classes; in some strains, direction of paw usage is learned or conditioned by the direction of the initial test chamber and the experience of reaching and, in other strains, paw usage is a constitutive behaviour not affected by previous experience. We report the evidence for locus heterogeneity in the cause of constitutive versus experience-conditioned paw usage from a phenotypic analysis of F1 hybrid generations from the experience-conditioned C57BL/6J, C3H/HeHa, and SWV strains and the constitutive CDS/Lay and DBA/2J strains. The F1 hybrids between strains of different phenotypic classes provide evidence of locus heterogeneity. Constitutive paw usage in CDS/Lay is phenotypically dominant to experience-conditioned behaviour in both C57BL/6J and SWV. However, constitutive paw usage in DBA/2J is phenotypically recessive to experience-conditioned behaviour in C57BL/6J and dominant to experience-conditioned behaviour in SWV. Among the experience-conditioned strains, C57BL/6J is highly lateralized but SWV is only weakly lateralized. Our data suggest a model in which C57BL/6J may have a "strong" allele that identifies a functional difference between the constitutive paw usage of CDS/Lay and DBA/2J. DBA/2J may have a loss-of-function mutation at the same locus that is recessive to the strong C57BL/6J allele. SWV may have a "weak" allele and the (SWV x D2)F1 compound heterozygote may be below a threshold for detectability of experience-conditioned behaviour, making the constitutive behaviour of DBA/2J appear to be dominant to the experience-conditioned behaviour of SWV. CDS/Lay may have a dominant allele at a second locus that suppresses experience-conditioned behaviour in all F1 hybrids.

Animals↗
PubMed1998

Effects of two-year treatment with the cholinesterase inhibitor rivastigmine on behavioural symptoms in Alzheimer's disease.

Alzheimer's disease (AD) is accompanied by prominent behavioural disturbances. They cause significant distress for both caregivers and patients and can play a major role in the decision to institutionalise AD patients. Recent evidence suggests that cholinergic deficiencies not only contribute to the memory and cognitive abnormalities of AD but are also responsible for some behavioural abnormalities seen over the course of the disease. In this study we assessed the ability of rivastigmine, a pseudo-irreversible cholinesterase inhibitor, to improve behavioural and psychopathologic symptoms in AD. The analysis included 34 patients present in the Germanarm of the international study B303 who received and completed long-term treatment with rivastigmine in the open-label study B305. Assessments of behaviour and psychopathological symptoms were performed using the behavioural component of the Clinicians Interview Based Impression of Change Plus (CIBIC-Plus). Results show that long-term treatment with rivastigmine can slow the progression of behavioural and psychopathological symptoms of AD. Behavioural symptoms showing stabilisation included aggressiveness, activity disturbances, hallucinations and paranoid features. Results also suggest that patients treated earlier with rivastigmine may attain a greater benefit compared with patients whose treatment is delayed 6 months. Further studies examining the effects of rivastigmine on behavioural disturbances in AD are therefore warranted.

Journal Article↗
PubMedDate not supplied

Bulimia and impulsive behaviour in middle adolescence.

BACKGROUND: In clinical samples, bulimia seems to be associated with various dyscontrol behaviours suggesting weakness in impulse control. Population studies of adolescents, however, are needed. We evaluated the association between self-reported bulimic behaviour and a number of dyscontrol behaviours, namely bullying, truancy, excessive drinking and sexual disinhibition among adolescents aged 14-16. This is the first study on bulimia and impulsivity in a large non-selected adolescent population sample. METHODS: A self-report questionnaire was administered to a representative population sample of 14- to 16-year-old adolescents (pupils of the 8th and the 9th grades of secondary school in four different regions in Finland). 4,453 girls and 4,334 boys aged 14-16 participated. The participation rate was 85.5%. RESULTS: Bulimic behaviour was associated with bullying, truancy, excessive drinking and sexual disinhibition among both sexes. Odds ratios for bulimic-type eating pathology according to each of these behaviours varied between 1.7 and 4.1. The more dyscontrol behaviours occurred simultaneously, the more likely was bulimic-type eating pathology. CONCLUSIONS: There is an association between bulimic behaviour and dyscontrol behaviours in the general population of adolescent girls and boys.

Adolescent↗
PubMed2003

The influence of piglet birth weight on physical and behavioural development in early life.

The objective of this study was to determine whether body weight at birth influences the physical and behavioural development of the neonatal pig. Sixteen sows and their litters were randomly allocated into four treatment groups. From the normal distribution curve of their birth weight, piglets were sub-divided into three groups: (1) low (<10th percentile) (2) normal (10-90th percentile) and (3) high (>90th percentile). To assess behavioural development, each litter was exposed to a ball placed in the creep area for a period of 1,800 s, and evaluated once over a 3-day period starting on either 5, 7, 14 or 21 days of postnatal life. Their response to, and interaction with, an object was used to calculate a numerical index of piglet behavioural development. Teat order was calculated following observations during consecutive suckling on days 11, 13 and 15 of life, and dominance hierarchy was assessed on day 12, 14 and 16. Individual body weight was recorded on days 0, 5, 7, 14 and 21 of postnatal life. Statistical differences between groups were analysed using general linear model, analysis of variance. Regression analyses were used to determine relationships between physical and behavioural development with teat order and dominance. There was a significant (p < 0.001) relationship between birth weight, growth performance and behavioural development. Behavioural developmental index (BDI) significantly improved (p < 0.001) with age and was also influenced by the day on which the ball was introduced (p < 0.01). Body weight on day 1 of the test was significantly (p < 0.001) correlated to BDI and age at test. Piglets demonstrating compensatory growth were more dominant and exhibited an improved behavioural developmental score than their slower growing littermates. In conclusion, compromised growth in utero can have a detrimental effect on the physical and behavioural development of the neonate. Animals with an enhanced developmental index in conjunction with a higher dominance value exhibited a improved neonatal growth performance.

Animals↗
PubMed1987

Intracerebroventricular oxytocin stimulates maternal behaviour in the sheep.

The maternal behaviour of 7 ovariectomized, oestrogen-treated ewes was recorded after intracerebroventricular (ICV) infusions of oxytocin (OT). At weekly intervals 10-min behaviour tests were given starting 1 min after control (saline) or OT infusions. In the ewes' home pens, 5-, 10- and 20-micrograms doses of OT significantly increased the frequency of some or all of the maternal behaviours scored (low-pitch bleats, sniffing, licking and approaching/following the lamb), and 3 ewes allowed suckling attempts. Aggressive (head butts) and negative (withdrawal from the lamb) behaviours significantly decreased in frequency. Vaginocervical stimulation (10 min duration) produced similar effects on these behaviours. When the lambs were removed from the ewes' pens, the ewes exhibited significantly more high-pitch bleats (protest) following OT treatment. When 20 micrograms OT was given ICV in the absence of oestrogen priming, or when it was given intravenously with oestrogen priming, no significant effects on maternal behaviour were seen. Maternal behaviour was also significantly stimulated in oestrogen-treated ewes in a larger, novel testing environment (an enclosed area of field) following 5- and 20-micrograms doses of OT. In an additional experiment in the field enclosure it was found that ewes spent significantly more time near a lamb in a cage following both 5- and 20-micrograms doses of OT. In both experimental settings the high OT doses (10 and 20 micrograms) significantly increased the frequency of feeding although the effect was not dependent on oestrogen priming. These results demonstrate that central OT may play an important role in stimulating maternal behaviour in the sheep.

Animals↗
PubMed2004

Modern concepts of socialisation for dogs: implications for their behaviour, welfare and use in scientific procedures.

The provision of a socialisation and training programme for dogs can lead to an improvement in the quality of the data that are produced from scientific procedures, and also to an improvement in animal welfare. A reduction in the number of animals needed to produce statistically significant data can result from decreasing the variability of the experimental data. The effects of a dog's behaviour can be a major source of random variability. A well socialised, habituated and trained dog should be calm during experimental procedures and, for example, during an ECG measurement, thus providing good quality data. A fearful, poorly socialised dog may also appear to be well-behaved on an examination table, and during an ECG measurement, because of the freezing response. However, there is likely to be a difference in the level of stress that these two individuals experience during the procedures. The stress response can have an impact on vital physiological parameters, such as heart rate. The variability in these parameters and the behaviour exhibited within a group of socialised, habituated and trained dogs that have been well prepared for experimental procedures, should be less than the variability present within a similar group of dogs that have not been prepared for these procedures. This paper describes two socialisation programmes, which were designed in order to compare the heart rates and behaviour of dogs which had received different degrees of socialisation, habituation and training. The behaviour of small groups of dogs from this study was compared with that of dogs on a standard socialisation programme, by using a simple, reproducible behavioural score scheme. The heart rate of the dogs was also measured. The results showed that there was little difference in heart rate between the groups, but that there were significant differences in the scores for key behaviours. There was evidence of a decrease in the variability of the behavioural scores for the groups of dogs that had undergone an intensive socialisation programme. Therefore, a socialisation programme can have a significant effect on behaviour and welfare, and has the potential to improve the quality of the data that are recorded.

Animal Welfare↗
PubMed1998

5-hydroxytryptamine and impulse control: prospects for a behavioural analysis.

Impulsiveness is a significant clinical problem associated with a variety of psychiatric and neuropsychiatric disorders. Clinical and experimental studies have provided evidence that individuals displaying impulsive behaviour tend to show signs of deficient functioning of the ascending 5-hydroxytryptaminergic (5-HTergic) pathways of the brain. A persistent problem in investigations of the biological basis of impulsive behaviour has been the lack of a satisfactory definition of 'impulsiveness', as distinct from other behavioural features, such as aggression, which are often apparent in 'impulsive' individuals. Research in the experimental analysis of behaviour suggests that two important characteristics of 'impulsiveness' are (i) deficient tolerance of delay of gratification and (ii) inability to inhibit or delay voluntary behaviour; both of these characteristics are amenable to study in laboratory animals. We describe some delayed reinforcement and delayed response paradigms which purport to capture these behavioural characteristics, and review recent evidence that manipulation of 5-HTergic function alters behaviour in these paradigms. It is argued that the two characteristics of 'impulsiveness' are themselves the product of disturbance of more fundamental behavioural processes; the nature of these processes is considered.

Animals↗
PubMed1998

GABAergic drugs and sexual behaviour in the rabbit: evidence for species-specific effects.

The effects of gamma-amino butyric acid (GABA)-ergic drugs on male rabbit sexual behaviour have been evaluated. The GABA(A) agonist 4,5,6,7-tetrahydroxixazolo-5,4c-pyridin-3-ol (THIP), the GABA(B) agonist R-baclofen and the GABA antagonists picrotoxin and bicuculline were used. Injection of THIP, 20 mg/kg, s.c. produced a complete suppression of sexual behaviour and R-baclofen, 2.5 mg/kg, s.c. a significant inhibition. Intraperitoneal injections produced effects at higher doses than did s.c. injections. The inhibition produced by R-baclofen was associated with strong motor effects as shown by the water escape test. It is probable, therefore, that the reduced sexual behaviour observed after treatment with this drug is a consequence of sedative or muscle relaxant effects. By contrast, the dose of THIP that inhibited sexual behaviour had no effect on the water escape test. These results show that the GABA(A) agonist inhibits sexual behaviour in the male rabbit independent of effects on the motor system. The GABA antagonists had marginal or no effects on sexual behaviour. When these data are compared to previous results in the rat, substantial differences are seen. As there are differences between the effects on rat and rabbit sexual behaviour by other types of drugs, it appears that drug action on sexual behaviour cannot be generalized from one species to another.

Animals↗
PubMed1984

Behavioural assessment of disturbed, institutionalized retardates.

While behavioural assessment has had wide application in a number of educational and treatment settings, relatively little has been done to develop programmes specifically for use with retardates who have been institutionalized for the treatment of disturbed behaviour. As a result, the development of appropriate procedures for the latter group requires extrapolation from the use of behavioural techniques in other settings. The current literature on behavioural assessment stresses the importance of identifying meaningful response units and their controlling variables, if efficacious treatment programmes are to be mounted. To be maximally useful, assessment must provide a relatively simple description in objective, non-inferential terms of how a patient responds to the demands of daily living. While many reports of treatment programmes focus on the assessment of a single, narrowly defined variable, the occurrence of which can be readily counted, this is not appropriate for the initial assessment procedures of a residential treatment centre. What is required is an omnibus approach which samples the patient's responses to a broad array of environmental situations which are relevant to the centre and its population. A review of available behavioural scales reveals that there are very few reliable omnibus scales available for use with retardates and none which adequately assesses the behavioural concommitants of disturbed retardates. To deal with this group of patients, it is proposed that, initially, two scales be used to sample both normal and maladaptive behaviour. A number of suggestions have been made for implementing behavioural assessment procedures in residential treatment centres, especially for disturbed retardates.

Activities of Daily Living↗
PubMed1991

Behaviour problems of the mentally retarded.

The behaviour profiles of 176 mentally retarded individuals from two reception centres and nine group homes were assessed. The correlations between behaviour and age, sex, degree of mental retardation, etiology of mental retardation and medical diagnosis were assessed using the Revised Child Behaviour Profile. The severity of behaviour disturbance did not vary with age or medical diagnosis. The moderately retarded subjects presented with more severe behaviour problems, such as aggression, than the severely mentally retarded subjects. The variable most predictive of behavioural problems was etiology of the disorder. Individuals with Down's syndrome had significantly fewer behaviour disturbances and those with autism and pervasive developmental disorder had significantly more behaviour disturbances than other subjects. A psychiatric disorder was found in 10.2% of the sample. The implications of these findings are discussed with respect to public policy.

Activities of Daily Living↗
PubMed2005

Evaluating the effectiveness of teacher training in Applied Behaviour Analysis.

Interventions for children with autism based upon Applied Behaviour Analysis (ABA) has been repeatedly shown to be related both to educational gains and to reductions in challenging behaviours. However, to date, comprehensive training in ABA for teachers and others have been limited. Over 7 months, 11 teachers undertook 90 hours of classroom instruction and supervision in ABA. Each teacher conducted a comprehensive functional assessment and designed a behaviour support plan targeting one behaviour for one child with an autistic disorder. Target behaviours included aggression, non-compliance and specific educational skills. Teachers recorded observational data for the target behaviour for both baseline and intervention sessions. Support plans produced an average 80 percent change in frequency of occurrence of target behaviours. Questionnaires completed by parents and teachers at the end of the course indicated a beneficial effect for the children and the educational environment. The potential benefits of teacher implemented behavioural intervention are discussed.

Adolescent↗
PubMed2004

Effects of galantamine on behavioural and psychological disturbances and caregiver burden in patients with Alzheimer's disease.

BACKGROUND: Behavioural and psychological disturbances occur in up to 90% of patients with Alzheimer's disease (AD), have a substantial impact on both patients and caregivers, and are often associated with the decision to institutionalise patients. Galantamine (Reminyl) is a dual-acting cholinergic treatment that improves cognitive and functional performance, delays the onset of behavioural symptoms and decreases behaviour-associated caregiver distress. OBJECTIVE: To assess the impact of galantamine on behavioural disturbances and associated caregiver burden in non-institutionalised patients with AD. METHODS: This was a 3-month, open-label, multicentre study in Switzerland. Patients with mild-to-moderate AD received galantamine (escalated from 8 to 24 mg/day over 8 weeks). The primary outcome was the Neuropsychiatric Inventory (NPI) for patients who completed 3 months treatment (observed cases, OC). Secondary outcomes included the Nurses' Observation Scale for Geriatric patients (NOSGER), and the Clinical Global Impression (CGI) of change. RESULTS: 124 patients (mean age 75.2 years, 55.6% women) received galantamine and were included in the intention-to-treat (ITT) safety analysis. Significant improvements in NPI scores versus baseline were seen in the OC analysis (p < 0.05, N = 91); mean total NPI scores (+/- SE) were reduced from 14.9 +/- 1.2 at baseline to 11.3 +/- 1.2 at month 3. Eleven out of 12 NPI domains were improved. Anxiety, aberrant motor behaviour, delusions, euphoria and night-time-behaviour all improved by > 30%. Symptoms with the highest baseline frequency and severity improved by 19-27%. A significant reduction in total NPI caregiver burden was observed at month 3 (p < 0.05). Despite this short assessment period the NOSGER evaluation and physicians' CGI also showed improvement. Adverse events (AEs) were mostly gastrointestinal. CONCLUSION: Galantamine significantly reduced behavioural disturbances after 3 months in this population and this had a positive impact on behaviour-related caregiver burden. Galantamine showed the expected safety profile and was well tolerated.

Aged↗
PubMed1996

Plasma beta-endorphin concentrations in people with learning disability and self-injurious and/or autistic behaviour.

BACKGROUND: It has been suggested that the key variable in reduced plasma immunoreactive beta-endorphin concentrations in autistic subjects may be concomitant self-injurious behaviour. METHOD: We studied morning levels of plasma beta-endorphin in 33 learning disabled people with self-injurious and/or autistic behaviour. RESULTS: The beta-endorphin level of the subjects with severe self-injurious behaviour proved to be significantly lower than of autistic subjects without severe self-injurious behaviour (3.6 (1.4) pmol/l v. 5.8 (4.3) pmol/l; t-test: P = 0.045. Replication: 3.7 (1.1) pmol/l v. 5.7 (3.8) pmol/l; t-test: P = 0.043). Individuals with mild and occasional self-injurious behaviour were found to have beta-endorphin levels comparable to those without self-injurious behaviour. Further, subjects being treated with neuroleptics and lower beta-endorphin levels than untreated subjects. CONCLUSIONS: These results stress that in any study of opioid systems of learning disabled people, it is very important to differentiate between people with and without severe self-injurious behaviour. The results support the idea that severe self-injurious behaviour may be related to functional disturbances in the endogenous opioid system.

Adult↗