This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
There’s a popular saying in the autism community: “
If you’ve met one person with autism, you’ve met one person with autism.” Although this phrase is meant to convey the remarkable variation in abilities and disabilities among people with autism spectrum disorder (ASD), we’re learning that it also applies to the extraordinary variability in how ASD develops. When I first began doing research on autism decades ago, we thought of it as one condition and aimed to discover its “cause.” Now we know ASD is actually a group of lifelong conditions that can arise from a complex combination of multiple genetic and environmental factors. In the same way that each person with ASD has a unique personality and profile of talents and disabilities, each also has a distinct developmental history shaped by a specific combination of genetic and environmental factors.
More evidence of this extraordinary variety will be presented this week in Baltimore, where nearly 2,000 of the world’s leading autism researchers will gather for the International Meeting for Autism Research (IMFAR). As president of the International Society for Autism Research, which sponsors the conference, I am more impressed than ever with the progress we are making. New findings being presented at the conference will highlight the importance of the prenatal period in understanding how various environmental factors such as exposure to alcohol, smoking and certain chemical compounds can increase risk for ASD. The impact of many environmental factors depends, however, on an individual’s genetic background and the timing of the exposure. Other research links inflammation—detected in blood spot tests taken at birth—with a higher likelihood of an ASD diagnosis later on. Researchers suggest that certain factors such as maternal infection and other factors during pregnancy may influence an infant’s immune system and contribute to risk. As our knowledge of these risk factors grows, so do the opportunities for promoting healthy pregnancies and better outcomes.
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Autism in the developing brain
Among the most exciting developments in the field are results from a large-scale longitudinal study of the brains of infants with older siblings who have autism. About 20 percent of these infants will develop ASD. This study is providing an in-depth picture of how the brain develops in a child with autism and how this differs from a neurotypical child. State-of-the-art brain
-imaging techniques are revealing the physical connections among different brain regions. By examining these detailed scans, researchers have detected differences in brain circuitry in infants who later develop ASD. Such differences are evident during the first year of postnatal life and can help us detect ASD as soon as—or even before—symptoms emerge. The goal is to start intervention even earlier in development when the brain is rapidly developing and most plastic. We have come a long way from the studies my colleagues and I conducted in the 1990s in which we used home videotapes to detect early symptoms of autism.
Research on brain development is helping us understand why people with autism have difficulty navigating the social world, and also why many show exceptional talents in areas such as math, music and art. Studies have found that long-range connections between different brain regions are weaker in people with ASD. Complex behaviors such social interaction and language depend on the precise coordination of distant brain regions. Some studies have found that people with ASD have enhanced short-range neural connections, which might explain why ASD can be associated with exceptional skills in specific domains, such as visual memory. These brain differences also can lead to unusual perceptual and sensory experiences, including both heightened and reduced sensitivity to sound, sight, touch and other inputs. Several studies, for example, are exploring how people with autism perceive pain, especially those who engage in self-injury. Findings suggest that brain regions that typically respond when pain is felt are not as active.
We are also learning more about the role of gender in autism. When I first began working in the clinic, we would see five or six boys for every girl on the spectrum. Nearly all research was focused on boys. In recent years this has begun to change. We have come to realize that females with ASD often have different and milder symptom profiles than do boys, causing their diagnosis to be missed or delayed. This means girls are often missing out on access to early intervention—a fact that might explain why they often struggle more than boys do in areas such as daily living skills. In fact, research on females with ASD is leading us to question whether we need new or adapted screening or diagnostic tools to ensure that girls aren’t put at a disadvantage.
Better targeted treatments
This year at IMFAR, a number of promising new treatments will be unveiled. Increasingly these are targeted to the individual. For example, many people with ASD also suffer from anxiety or attention deficits, and research shows that addressing these challenges can greatly improve their quality of life. The next frontier is to devise treatments for specific genetic subtypes. For example, people with a rare genetic syndrome called
tuberous sclerosis complex (TSC) often develop autism. Researchers have identified a specific pathway in the brain—the mTOR signaling pathway—that is disrupted in people with TSC. By inhibiting this pathway in mice, they’ve managed to reverse ASD symptoms. Scientists are now working to translate this promising work to humans. Because TSC can be diagnosed before ASD symptoms are present, this work offers the hope of preventing cognitive impairment and other symptoms.
Whereas we are encouraged by the prospects for new treatments, we remain challenged in helping people access interventions that are already well established, such as early behavioral therapy. Cost and culture stand as barriers to many who would benefit. We also must do a better job of helping adults with ASD. Some of the research to be presented in Baltimore examines the effectiveness of adult interventions that range from cognitive training to mindfulness-based therapies. Studies are finding that treatments for autism must cover the whole life span and consider the broader context in which the person with autism lives, including family and community. We increasingly recognize the importance of providing support to the whole family, including siblings.
For much of the past two decades, popular discussion of autism has focused on the puzzling rise in its prevalence. That rise might have leveled off. According to the latest report from the Centers U.S. Centers for Disease Control and Prevention, the prevalence in children is holding steady at one in every 68 children. Now our attention must turn to ensuring that each unique person with ASD can reach his or her full potential and enjoy a meaningful and productive life. As a researcher and a clinician working every day with people with ASD and their families, I am more encouraged than ever about our progress in understanding a condition that was largely a mystery just two decades ago.