Autism spectrum disorder (ASD) and autism are both general terms for a group of complex disorders of brain development. These disorders are characterized, in varying degrees, by difficulties in social interaction, verbal and nonverbal communication and repetitive behaviors. With the May 2013 publication of the DSM-5 diagnostic manual, all autism disorders were merged into one umbrella diagnosis of ASD. Previously, they were recognized as distinct subtypes, including autistic disorder, childhood disintegrative disorder, pervasive developmental disorder-not otherwise specified (PDD-NOS) and Asperger syndrome.
ASD can be associated with intellectual disability, difficulties in motor coordination and attention and physical health issues such as sleep and gastrointestinal disturbances. Some persons with ASD excel in visual skills, music, math and art.
Autism appears to have its roots in very early brain development. However, the most obvious signs of autism and symptoms of autism tend to emerge between 2 and 3 years of age. Autism Speaks continues to fund research on effective methods for earlier diagnosis, as early intervention with proven behavioral therapies can improve outcomes. Increasing autism awareness is a key aspect of this work and one in which our families and volunteers play an invaluable role.
Not long ago, the answer to this question would have been “we have no idea.” Research is now delivering the answers. First and foremost, we now know that there is no one cause of autism just as there is no one type of autism. Over the last five years, scientists have identified a number of rare gene changes, or mutations, associated with autism. A small number of these are sufficient to cause autism by themselves. Most cases of autism, however, appear to be caused by a combination of autism risk genes and environmental factors influencing early brain development.
In the presence of a genetic predisposition to autism, a number of nongenetic, or “environmental,” stresses appear to further increase a child’s risk. The clearest evidence of these autism risk factors involves events before and during birth. They include advanced parental age at time of conception (both mom and dad), maternal illness during pregnancy and certain difficulties during birth, particularly those involving periods of oxygen deprivation to the baby’s brain. It is important to keep in mind that these factors, by themselves, do not cause autism. Rather, in combination with genetic risk factors, they appear to modestly increase risk.
A growing body of research suggests that a woman can reduce her risk of having a child with autism by taking prenatal vitamins containing folic acid and/or eating a diet rich in folic acid (at least 600 mcg a day) during the months before and after conception.
Increasingly, researchers are looking at the role of the immune system in autism. Autism Speaks is working to increase awareness and investigation of these and other issues, where further research has the potential to improve the lives of those who struggle with autism.
An atrial septal defect (ASD) is a hole in the wall between the two upper chambers of your heart (atria). The condition is present from birth (congenital). Small atrial septal defects may close on their own during infancy or early childhood.
Large and long-standing atrial septal defects can damage your heart and lungs. Small defects may never cause a problem and may be found incidentally. An adult who has had an undetected atrial septal defect for decades may have a shortened life span from heart failure or high blood pressure that affects the arteries in the lungs (pulmonary hypertension). Surgery may be necessary to repair atrial septal defects to prevent complications.
Many babies born with atrial septal defects don't have associated signs or symptoms. In adults, signs or symptoms usually begin by age 30, but in some cases signs and symptoms may not occur until decades later.
Atrial septal defect signs and symptoms may include:
Contact your doctor if you or your child has any of these signs or symptoms:
These could be signs or symptoms of heart failure or another complication of congenital heart disease.
Autism spectrum disorder (ASD) is a brain-based condition – that is, where the brain hasn’t developed in a typical way. Although no two children with ASD are the same, they all face challenges in interacting and communicating with others. And they also have either a narrow range of interests or engage in repetitive activities.
We don’t know exactly what causes autism spectrum disorder (ASD). But the latest research shows that in children with ASD:
Children with autism spectrum disorder (ASD) have a wide range of difficulties and abilities. In fact, some have very impressive skills and strengths. One child with ASD might know lots of words and have a very good memory. Other children might respond mostly to things they can see, making them good at completing puzzles and sorting objects by shape and colour.
By about the age of three, however, all children with ASD will show difficulties in two main areas – social communication, and interests and behaviour.
Children with ASD usually take longer than other children to learn language and often find it hard to make sense of language, so understanding simple instructions and social norms can be difficult. Almost all children with ASD learn at least some language but they don’t always communicate for purely social reasons and often appear to be uninterested in social contact with others.
When children with ASD do have language skills, they:
Narrow interests and repetitive behaviour
Even from a young age, children with ASD will often prefer the same routines. They might:
Many children with ASD also like to repeat behaviour, sometimes in an obsessive way. They might:
Older children with ASD might have very narrow and intense interests. For example, they might be interested in trains, always choosing a toy train over other toys, labelling every train in their surroundings, and insisting on repeatedly watching cartoons or videos that feature trains. If they have strong verbal skills, they might talk only about trains.
Many children with ASD also have sensory issues. They might:
Diagnosis of autism spectrum disorder (ASD) is based on a child not reaching certain age-based developmental milestones, because there are no other physical characteristics of the condition.
Signs of ASD are often present early in infancy, but become more noticeable in the toddler years, as children are expected to start talking and playing with other children. The first sign of ASD that most parents notice is their child’s lack of interest in other people. For example, many babies later diagnosed with ASD don’t look at their parents while being held or during nappy changes.
Children who are diagnosed with ASD will get a description of how severe their symptoms are and the amount of support they need. This ranges from `requiring support’ to ‘requiring very substantial support’.
Health professionals will also look at children’s language and cognitive abilities. Some children with ASD have intelligence in the typical range, but others have below-average intelligence.
Children who show difficulties in social communication only might be diagnosed with social communication disorder, rather than ASD.
If you’re concerned about your child’s development, talk to your health care provider about a developmental assessment. Finding out for sure is the first step to helping your child and getting services and programs suited to your child’s needs.
It’s important to get help and support as soon as possible. The sooner children get early intervention services, the more effective these services can be.
A paediatrician, psychiatrist, psychologist or other professional trained in ASD can diagnose ASD. They’ll use a combination of behaviour tests (watching the child play and interact) and interviews with parents about the child’s development.
The prevalence of autism spectrum disorder (ASD) has risen since the 1990s. Research suggests that the apparent increase is at least partly because of:
Some researchers suggest that recent changes in the criteria used when diagnosing ASD will affect the number of people diagnosed with ASD. Some argue that the changes will lead to an increase in the number of people diagnosed with ASD, while others think it will lead to a decrease. This is because of the diagnostic criteria and how researchers measure prevalence.
In the past, most studies focused on measuring the prevalence of ASD in general, or of autistic disorder. Fewer focused on Asperger’s disorder or PDD–NOS. Now that all these categories have been combined into one, it’s likely to affect the prevalence of ASD.
Once someone is found to have an atrial septal defect, a determination of whether it should be corrected has to be made.
Surgical mortality due to closure of an ASD is lowest when the procedure is performed prior to the development of significant pulmonary hypertension. The lowest mortality rates are achieved in individuals with a pulmonary artery systolic pressure of less than 40 mmHg.
If Eisenmenger's syndrome has occurred, there is significant risk of mortality regardless of the method of closure of the ASD. In individuals who have developed Eisenmenger's syndrome, the pressure in the right ventricle has raised high enough to reverse the shunt in the atria. If the ASD is then closed, the afterload that the right ventricle has to act against has suddenly increased. This may cause immediate right ventricular failure, since it may not be able to pump the blood against the pulmonary hypertension.
Closure of an ASD in individuals under age 25 has been shown to have a low risk of complications, and individuals have a normal lifespan (comparable to a healthy age-matched population). Closure of an ASD in individuals between the ages of 25 and 40 who are asymptomatic but have a clinically significant shunt is controversial. Those that perform the procedure believe that they are preventing long-term deterioration in cardiac function and preventing the progression of pulmonary hypertension.
Methods of closure of an ASD include surgical closure and percutaneous closure.
Although invasive, surgical closure is particularly beneficial because additional drug therapy is not needed. This is considered to be the gold standard to prevent PFO and paradoxical embolism.
Percutaneous device closure involves the passage of a catheter into the heart through the femoral vein guided by fluoroscopy and echocardiography. An example of a percutaneous device is the Cardia PFO occluder which has discs that can expand to a variety of diameters at the end of the catheter. The catheter is placed in the right femoral vein and guided into the right atria. The catheter is guided through the atrial septal wall and one disc (left atrial) is opened and pulled into place. Once this occurs, the other disc (right atrial) is opened in place and the device is inserted into the septal wall. This type of PFO closure is more effective than drug or other medical therapies for decreasing the risk of future thromboembolism.
Drug therapy can be used to minimize risk of thromboembolism and stroke in PFO. Anticoagulants, such as warfarin, are commonly used to reduce blood clotting, whereas antiplatelet agents, such as aspirin, to reduce platelet aggregation and thrombosis.
Prior to correction of an ASD, an evaluation is made of the severity of the individual's pulmonary hypertension (If present at all) and whether it is reversible (Closure of an ASD may be recommended for prevention purposes, to avoid such a complication in the first place. Pulmonary hypertension is not always present in adults that are diagnosed with an ASD in adulthood).
If pulmonary hypertension is present, the evaluation may include a right heart catheterization. This involves placing a catheter in the venous system of the heart and measuring pressures and oxygen saturations in the SVC, IVC, right atrium, right ventricle, pulmonary artery, and in the wedge position. Individuals with a pulmonary vascular resistance (PVR) of less than 7 wood units show regression of symptoms (including NYHA functional class). On the other hand, individuals with a PVR of greater than 15 wood units have increased mortality associated with closure of the ASD.
If the pulmonary arterial pressure is more than 2/3 the systemic systolic pressure, there should be a net left-to-right shunt of at least 1.5:1 or evidence of reversibility of the shunt when given pulmonary artery vasodilators prior to surgery. (If Eisenmenger's physiology has set in, it must be proven that the right-to-left shunt is reversible with pulmonary artery vasodilators prior to surgery.)
Until the early 1990s, surgery was the usual method for closing all ASDs. Now, thanks to medical advances, doctors can use catheterprocedures to close secundum ASDs, the most common type of ASD. During the procedure, the doctor inserts a catheter (a thin, flexible tube) into a vein in the groin (upper thigh) and threads it to the heart's septum. The catheter has a tiny umbrella-like device folded up inside it. When the catheter reaches the septum, the device is pushed out of the catheter and positioned so that it plugs the hole between the atria. The device is secured in place and the catheter is withdrawn from the body. Within 6 months, normal tissue grows in and over the device. There is no need to replace the closure device throughout the patient's life. Doctors often use echocardiography (echo) or transesophageal echo (TEE) as well as angiography to guide them in threading the catheter to the heart and closing the defect. TEE is a special type of echo that takes pictures of the heart through the esophagus (the passage leading from the mouth to the stomach). Catheter procedures are much easier on patients than surgery because they involve only a needle puncture in the skin where the catheter is inserted. This means that recovery is faster and easier. The outlook for patients having this procedure is excellent. Closures are successful in more than 9 out of 10 patients, with no significant leakage. Rarely, a defect is too large for catheter closure and surgery is needed.
Due to the communication between the atria that occurs in ASDs, disease entities or complications from the condition, are possible. Patients with an uncorrected atrial septal defects may be at increased risk for developing a cardiac arrhythmia, as well as more frequent respiratory infections.
ASDs, and particularly PFOs, are a predisposing risk factor for decompression sickness in divers because a proportion of venous blood carrying inert gases, such as helium or nitrogen does not pass through the lungs. The only way to release the excess inert gases from the body is to pass the blood carrying the inert gases through the lungs to be exhaled. If some of the inert gas-laden blood passes through the PFO, it avoids the lungs and the inert gas is more likely to form large bubbles in the arterial blood stream causingdecompression sickness.
Venous thrombus (clots in the veins) are quite common. Embolizations (dislodgement of thrombi) normally go to the lung and causepulmonary emboli. In an individual with ASD, these emboli can potentially enter the arterial system. This can cause any phenomenon that is attributed to acute loss of blood to a portion of the body, including cerebrovascular accident (stroke), infarction of the spleen or intestines, or even a distal extremity (i.e., finger or toe).
This is known as a paradoxical embolus because the clot material paradoxically enters the arterial system instead of going to the lungs.
Surgical closure of an ASD involves opening up at least one atrium and closing the defect with a patch under direct visualization.
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