Regressive Autism

Regressive autism, also known as late-onset or acquired autism, is characterized by the loss of previously acquired developmental skills, particularly in social communication and interaction. This regression typically occurs between 15 and 30 months of age, where children may initially develop normally but then experience a decline in verbal communication, social engagement, and may exhibit decreased eye contact, along with an increase in repetitive behaviors. This regression often leads to significant distress for both the child and caregivers.

Explanations and Theories for Regressive Autism

1. Genetic Factors: There is evidence suggesting a genetic predisposition to regressive autism. Children with this form of autism may have a family history of autism or other developmental disorders, indicating a potential genetic component (Zwaigenbaum et al., 2009).

2. Environmental Triggers: Environmental factors, such as exposure to certain toxins, infections, or other external stressors, have been hypothesized to trigger regression in children who are genetically predisposed. However, clear causal relationships are not well established (Hertz-Picciotto et al., 2006).

3. Immune System Abnormalities: Abnormal immune responses or autoimmunity have been linked to regressive autism. Research has identified irregularities in the immune systems of children with autism, which might contribute to the regression of skills (Ashwood et al., 2006).

4. Neurological Factors: Changes in brain structure and function, including abnormalities in brain development and connectivity, are being explored as potential explanations for regression (Courchesne et al., 2007).

5. Mitochondrial Dysfunction: Mitochondrial dysfunction, which affects energy production in cells, is another area of research in autism, including regressive forms. Dysfunction in these cellular processes could impact neurodevelopment (Rossignol and Frye, 2012).

6. Neuronal Pruning: Abnormal neuronal pruning is a significant area of interest. Neuronal pruning is a natural process during brain development where excess neurons and synaptic connections are eliminated to optimize brain function. In autism, including regressive autism, either excessive pruning (leading to a loss of necessary neural connections) or insufficient pruning (resulting in too many synapses) could disrupt normal brain function and development. This disruption may contribute to the loss of previously acquired skills in regressive autism (Tang et al., 2014; Varghese et al., 2017). Genetic studies have linked mutations in genes involved in synaptic pruning, such as MECP2, SHANK3, and PTEN, to autism spectrum disorders (Penzes et al., 2011). [READ MORE ON NEURONAL PRUNING]

Citations

• Zwaigenbaum, L., et al. (2009). The changing epidemiology of autism spectrum disorders. Canadian Journal of Psychiatry, 54(7), 533-540.
• Hertz-Picciotto, I., et al. (2006). The CHARGE study: an epidemiologic investigation of genetic and environmental factors contributing to autism. Environmental Health Perspectives, 114(7), 1119-1125.
• Ashwood, P., et al. (2006). The immune response in autism: a new frontier for autism research. Journal of Leukocyte Biology, 80(1), 1-15.
• Courchesne, E., et al. (2007). Mapping early brain development in autism. Neuron, 56(2), 399-413.
• Rossignol, D. A., & Frye, R. E. (2012). Mitochondrial dysfunction in autism spectrum disorders: a systematic review and meta-analysis. Molecular Psychiatry, 17(3), 290-314.
• Tang, G., et al. (2014). Loss of mTOR-dependent macroautophagy causes autistic-like synaptic pruning deficits. Neuron, 83(5), 1131-1143.
• Varghese, M., et al. (2017). Autism spectrum disorder: neuropathology and animal models. Acta Neuropathologica, 134(4), 537-566.
• Penzes, P., et al. (2011). Dendritic spine pathology in neuropsychiatric disorders. Nature Neuroscience, 14(3), 285-293.