Autism Spectrum Disorder

Autism Spectrum Disorder Definition/Description A neurodevelopmental condition characterised by qualitative impairment in social interaction and communication as well as repetitive stereotyped behaviour, interests and activities. Epidemiology • • More common in males Features usually manifest before the age of 2-3 years. Aetiology • • Genetics Environmental: - No specific causes identified - Toxin exposure - Prenatal infections esp. rubella - NO LINK TO THE MMR VACCINE - Obstetric complications - Mother having epilepsy - Mother being on SSRI especially in first trimester - Early gestational maternal hypothyroxinemia - Parental age ➔Either being 35 or more. Pathophysiology • • • • • Abnormal cellular configurations in several regions of the brain - Frontal and temporal lobes and the cerebellum. - Enlargement of the amygdala and hippocampus - Neurons present in select divisions of the pre-frontal cortex in an autopsy. The patches of abnormal neurons found in the frontal and temporal loves are involved in social, emotional, communication and language functions. - Early treatment -> improves ASD symptoms. Greater myelination in bilateral medical frontal cortices and less myelination in left temporoparietal junction. Region-specific differences in the concentrations of grey matter, made up of neuronal cell bodies, dendrites, unmyelinated axons and glial cells, are also found in the brains of people with autism GABA: - Prematurity - Reduced -> sensorimotor and behavioural anomalies ➔Reduced especially in cingulate region. ➔Key region for evaluation of social relationships, emotion and cognition ➔Fusiform gyrus -> important for face and facial expression evaluation. • • • • Behavioural measures of inhibition correlated with reductions in sensorimotor GABA concentrations. Glutathione (GSH): - Oxidative stress - Reduced in the dorsal anterior cingulate N-acetyl aspartate (NAA): - Reduced levels in the frontal, partial and temporal lobes, amygdala, hippocampus and thalamus. Mitochondrial dysfunction Neural inflammation Clinical features • • • • • • • • Persistent impairment in communication and social interactions. Restricted stereotyped patterns. Repetitive movements. Intellectual impairments Language impairments. Sensory abnormalities Associated conditions: - Epilepsy - Other neurodevelopmental and psychiatric disorders - Genetic conditions - Higher head circumference to brain volume ratio. Note: in mild autism there is no intellectual impairments Diagnosis • • • Hearing and vision testing Genetic testing - Fragile X syndrome Comprehensive evaluation: - Social interaction and communication skills - Language and comprehension skills - Behaviour - Cognitive development - Association conditions DSM-V criteria A. Persistent deficits in social communication and social interaction across multiple contexts, manifested by the following currently or by history: - Deficits in social-emotional reciprocity, failure to initiate or respond ot social interactions, failure of normal back and forth conversations, reduced sharing of interests, abnormal social approach. - Deficits in nonverbal communication behaviours used for social interaction, poorly integrated verbal and nonverbal communication, abnormal eye contact and body language, difficulty understanding gestures, lack of facial expressions and nonverbal communication. - Deficits in developing, maintaining and understanding relationships such as difficulties adjusting behaviours to suit various social contests, difficulties in sharing imaginative play or in making friends, absence of interest in peers. B. Repetitive patterns of behaviour, interests or activities as manifested by at least two of the following, currently or by history: - Stereotyped or repetitive motor movements, use of objects or speech. - Insistence of sameness, inflexible adherence to routines or ritualized pattern of verbal or nonverbal behaviour. ➔E.g. express distress at small changes, difficulties with transition, rigid thinking, need to take same routine, eating same foods. - Highly restricted, fixed interests that are abnormal in intensity or focus. ➔E.g. strong attachment or preoccupation with unusual objects, excessively circumscribed or preservative interests. - Hyperactivity or hypoactivity to sensory input or unusual interests in sensory aspects of the environment ➔E.g. apparent indifference to pain/temperature, adverse responses to sounds and textures, excessive smelling or touching objects. C. Symptoms must be present in the early developmental period - But may not become fully manifest until social demands exceed limited capacities or may be masked by learned strategies later in life. D. Symptoms cause significant impairment in social, occupational or other important aspects of current functioning. E. These disturbances are not better explained by an intellectual disability or a global developmental delay. • Specify if: - With or without accompanying intellectual impairment - With or without accompanying language impairment - Associated with a known medical or genetic condition or environmental factor. - Associated with another neurodevelopmental, mental or behavioural disorder - With catatonia Treatment and Management • • • Early behavioural and educational management - Should be started already in preschool children ➔Greatly improves outcomes - Competence training: social skills, communications skills - Establishing clear and consistent structures Family and support counselling - Parental education on interaction the with child and acceptance of their behaviour. Medical treatment - SSRIs ➔For depression - Antipsychotics ➔For irritability, aggression, self-harm, tics - Stimulants ➔For inattention