Hypothalamic-pituitary-adrenal axis function and hypothalamic-pituitary-thyroid axis function in mentally retarded oatients with and without self-injurious and/or aggressive behaviour

[摘要] English: The etiology of aggression and self-injuring behaviour in low functioningmentally retarded patients is multi-factorial and may reflect the presence ofundiagnosed psychiatric conditions, unapparent due to the degree of thepatient's impairment. It may also reflect hyperactivity of the stress response.The intricacies of diagnosis in this group of patients call for the developmentof biological markers to aid in diagnosis, therapy selection and drug responsemonitoring. Measuring and determining the relative contribution of individualneurotransmitters in the problem behaviour is complex and impractical.An alternative route may be to evaluate the functions of the hypothalamic-pituitaryaxis, which has extensive connections with the limbic area and isrelatively easy to assess. The hypothalamic-pituitary system controls thebehavioural, endocrine, autonomic and immunological responses to stress.The dexamethasone suppression test (OST) as adapted by Carroll and thethyroid-releasing hormone stimulation test (TRHST) has been extensivelyused in research on biological markers in major depression. Stress is knownto activate the hypothalamic-pituitary-adrenal (HPA) axis, reflected byelevated cortisol levels.The study is a matched control study comparing hypothalamic-pituitary-adrenalaxis function and hypothalamic-pituitary-thyroid axis function in 44institutionalised mentally retarded patients with and without self-injuring andaggressive behaviour through the measurement of baseline cortisol levels andthe application of the dexamethasone suppression test and the thyroid-releasinghormone stimulation test. The groups were matched according togender, age and level of functioning. The mean age of the aggressive group106was 44,1 years (±SO 9,8) and the mean age of the non-aggressive group was44,2 years (±SO 10,5).Baseline hypercortisolaemia occurred in five of the 22 aggressive subjects(22,7 %) and in two of the 22 non-aggressive subjects (9,1 %). Cortisol nonsuppressionwith the OST occurred in two subjects in the aggressive group(9,1 %) and one subject in the non-aggressive group (4,5 %). The OST did notdemonstrate a difference in the two groups, yet there were more individuals inthe aggressive group with abnormal high baseline cortisol, as well as atendency towards a higher baseline cortisol in the aggressive group,suggesting an abnormal or more reactive stress response. Higher baselinecortisol levels were not related to age or the type of aggression, yet subjectswith more recent aggressive activity showed higher baseline cortisol levels.The TRHST was generally well tolerated by the subjects. Side effects werefew and transient. There were two male subjects in the aggressive groupshowing a blunted TRHST. Primary hypothyroidism was demonstrated in oneof the female subjects in the non-aggressive group and subclinicalhypothyroidism in two subjects in the non-aggressive group, as well as in onesubject in the aggressive group.Longitudinal studies are needed to determine cortisol levels in unmedicatedpatients, in addition to comparing cortisol levels during different kinds oftreatment.

[发布机构] University of the Free State