Introduction: Autism spectrum disorder is a neurodevelopmental disorder that is often combined with other diseases, so the prognosis of patients is very poor, most of them need to be cared for for for life, which seriously affects the quality of life of patients. Clarifying the cause of the disease has become a top priority and will provide a basis for effective prevention, early diagnosis, and early intervention of autism spectrum disorder. At present, genetic and environmental factors are related to the occurrence of autism spectrum disorder, and genealogy studies, twin studies, etc. have shown that autism spectrum disorder is highly inherited.
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Understanding the epidemiological characteristics of autism spectrum disorder, the clinical prevalence of males will be higher than in females
1. Population distribution
Autism spectrum disorders begin in infancy and early childhood, develop symptoms gradually at 12–18 months of age, and can be diagnosed at 24 months of age. According to the World Health Organization, 1 in 160 people worldwide suffers from autism spectrum disorder, or a prevalence of 6.25 per thousand. The prevalence in men is higher than in women, according to data released by the U.S. Centers for Disease Control and Prevention's Surveillance Center for Autism and Developmental Disabilities in 2018.
The prevalence of autism spectrum disorder in 8-year-olds is as high as 16.8 per thousand, the prevalence of males is 26.6‰ and that of females, and the prevalence of males is about 4 times that of females; the prevalence of non-Hispanic white children is 17.2‰, the prevalence of non-Hispanic black children is 16.0‰, and the prevalence of Hispanic children is 14.0‰.
There is still a lack of monitoring systems for autism spectrum disorders in mainland China, and the results of meta-analysis based on data on the prevalence of autism spectrum disorders in the general population of the mainland show that the prevalence of autism spectrum disorders is 3.923 per thousand, the prevalence of autism spectrum disorder is 7.277 per thousand, the prevalence of females is 1.645 per thousand, and the prevalence of males is 4.4 times that of females.
2. Regional distribution
Oxford researchers summarized the prevalence of autism spectrum disorders in various countries from 1990 to 2017 and plotted them on the world map for the prevalence of autism spectrum disorders in various countries in 2017, and the prevalence of autism spectrum disorders in mainland China was lower than in other countries.
According to the data it provides, the prevalence of autism spectrum disorder in Canada was the highest at 9.4 per thousand in 2017, followed by Japan at 8.5 per thousand and the continental prevalence of 4.0 per thousand. The results of a meta-analysis of the prevalence of autism spectrum disorder in Asia showed that the prevalence was highest in East Asia, at 5.1 per thousand, higher than in Western Asia (3.5 per thousand) and South Asia (3.1 per thousand).
The results of the meta-analysis of the prevalence of autism spectrum disorder in mainland China showed that the prevalence in rural areas was 6.226 ‰, the prevalence in urban areas was 3.273 ‰, and the prevalence in rural areas was 1.9 times that of urban prevalence; the prevalence rate in eastern Mainland China was 4.581 ‰, and the prevalence rate in central China was 5.085 ‰. Another continental meta-analysis showed that the prevalence in the south of the continent was 5.467 per thousand, higher than the 1.591 per thousand in the north.
3. Time distribution
The prevalence of autism spectrum disorder continues to rise, which may be related to the improvement of diagnosis and screening methods of autism spectrum disorder, and the improvement of parents' and guardians' awareness of the disease. Survey data from the U.S. Centers for Disease Control and Prevention's Surveillance Center for Autism and Developmental Disabilities show that the prevalence of autism spectrum disorder in 8-year-olds rose from 9 per thousand in 2006 (1 in 111 people) to 14.7 per thousand in 2010 (1 in 68 people).
Recently published data in 2014 show that the prevalence has risen to 16.8 per thousand (1 in 60 people). In 2015, Hao Xiaohui's graduation thesis conducted a meta-analysis of 23 studies, and the results showed that the prevalence of autism in 2007 to 2010 was 1.591 ‰, lower than the prevalence of 5.467 ‰ from 2011 to 2014.
Children born in finland and Sweden in autumn have the highest risk of autism spectrum disorder, and children born in spring have the lowest risk of autism spectrum disorder. Researchers from the Second Affiliated Hospital of Nanjing Medical University in Mainland China compared the distribution of birth seasons between the children's group and the healthy children, and the results showed that the frequency of birth in the autism spectrum disorder group was significantly higher than that of the healthy control group, which was inconsistent with foreign studies.
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The onset of autism spectrum disorder is associated with a variety of factors and is a disease with a complex pathogenesis
1. Pathogenesis of autism spectrum disorder
The pathogenesis of autism spectrum disorder has not yet been understood, with the continuous deepening of research, researchers in molecular genetics, bioinformatics, biochemistry, epigenetics, electrophysiology, neurochemistry, neuroimmunology, neuroanatomy, neuroanatomy, cell and animal models and other aspects of research found that autism spectrum disorder is a complex mechanism of the disease.
Mainly related to neurodevelopmental abnormalities, dysfunction of neural pathways, synaptic and neural connection abnormalities, neurotransmitter imbalances, etc., synaptic function, translation and WNT signaling pathways are currently considered to be the main cellular pathways associated with the pathogenesis of autism spectrum disorders, and are usually affected by multiple types of genetic mutations.
Synaptic function, translation, and WNT signaling pathways are highly integrated, and WNT signaling controls key transcriptional programs that affect neuronal maturation and neural circuit formation, which also rely on synaptic activity during development, with local translation of synapses being the basis of synaptic plasticity and cognition, which is also stimulated by synaptic activity. These three pathways respond to and are influenced by neuronal activity.
The mTOR pathway also plays an important role in cellular pathways that are interconnected by neuronal activity. The mTOR signaling pathway regulates cell proliferation, growth, and neuronal morphogenesis, and mutations in genes in this pathway are closely associated with the occurrence of autism spectrum disorders.
PTEN is a tumor suppressor gene that mutates in many human cancers, and individuals with PTEN mutations are susceptible to tumors, but can also exhibit brain dysfunction, including cranial malformations, epilepsy, mental retardation, and can also lead to giant malformations of the mouse and human forebrains, which may be related to abnormal activation of the P13K/AKT pathway in specific neuronal populations.
2. Clinical features
The main core symptoms of children with autism spectrum disorder are social interaction disorders, communication disorders, and stereotyped repetitive behavior patterns and interests. Social communication disorder is manifested by a lack of interest and skills in social interaction, a lack of secure attachment relationships with their parents, and an inability to interact normally.
Communication disorders are manifested as: speech communication: speech is not developed or stunted, and even speech regression, speech comprehension ability has different degrees of defects, according to their own wishes to express difficulties; nonverbal communication: lack of understanding and use of non-verbal communication ability, nonverbal communication body language and eye annotation function is abnormal, facial expression is indifferent.
Stereotyped repetitive behaviors and interests manifest as repetitive or fixed use of objects, words, or actions that are very limited to quirky interests. In addition, children are often combined with other diseases, such as attention deficit hyperactivity disorder, anxiety disorder, bipolar disorder, inflammatory bowel disease, epilepsy, intellectual disability, neuritis, immune disease, schizophrenia, sensory problems, sleep disorders, etc.
3. Diagnosis
Diagnosis of autism spectrum disorder is based on behavioral characteristics and developmental conditions, and it is important to assess the observation and development of their behavior on a scale. Diagnostic criteria are based on DSM-V., and can be diagnosed by meeting the following five diagnostic criteria.
Diagnostic criteria are: deficits in social interaction and social communication in multiple settings; the presence of stereotyped repetitive patterns and interests; symptoms early in development; symptoms that cause clinically significant impairment in social, occupational, or other important areas; and these symptoms cannot be explained by intellectual disability or broad developmental disability.
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How should people with autism spectrum disorder be treated? There are currently no specific drugs to treat core symptoms
So far, there are no specific drugs to treat the core symptoms of autism spectrum disorder, but some drugs can help treat other symptoms in children, such as some atypical antipsychotic drugs can treat children's self-harm, aggression and other behaviors. Because children's developmental levels and symptoms vary widely, the current treatment of autism spectrum disorder encourages targeted, flexible and diverse integrated interventions, with special education and training as the main intervention.
These educational training courses include behavioral analysis therapy, sensory integration training, early intervention in the Denver model, and more. Early behavioural reinforcement interventions can greatly affect development, particularly in terms of behaviour, adaptability, and communication, and therefore advocate early detection, early diagnosis, and early treatment with the aim of enhancing socially acceptable behaviours and reducing or eliminating bad behaviours in children.
Conclusion: The etiology and pathogenesis of autism spectrum disorder are not clear, there are no specific drugs and treatments for core symptoms, and other diseases are often combined, so the prognosis of patients is very poor, most of them need to be cared for for life, which seriously affects the quality of life of patients. Studies have shown that 58%–78% of adults with autism spectrum disorder have poor outcomes in terms of independent living, education, employment and peer relationships.