Triveni Goswami Vernal
(Registered Special Educator CRR: A64010)

In life, people often tend to focus only on “progression”. Very rarely, do people even acknowledge the possibility of regression (loss of previously acquired skills) and when they do, they tend to associate regression with neurological conditions or brain injury, such as a Brain Stroke or Alzheimer’s or Parkinsons and in adults, usually. For most people, regression in children is rather unthinkable—that, children can lose skills as they grow, does not fit within the normal scheme of things, for them.
But, for a lot of families that have individuals on the Autism Spectrum, regression is an essential part of their lives.  Regression often comes in unannounced, in individuals with Autism.

Individuals with Autism are not devoid of skills, they have differing skill sets. In some skills, they may surpass their peers, in others, they may lag behind and, in some skills, they may be at par with their peers. Acquisition of skills may often take longer in comparison to their neurotypical peers. And for many individuals with Autism, regression in various forms may occur, throughout their lifespan.

In a small percentage of children, regression may take place around 2.5-3.5 years and that’s when they are usually officially diagnosed with the neurodevelopmental condition of Autism. The regression may usually take the form of loss of speech, social skills and a preference to spend time with oneself than with others.

BUT WHY DOES REGRESSION TAKE PLACE?
That’s one question I often asked myself, as my child had also regressed and lost all his speech and social skills, when he was around 2.5 years. And an even bigger question, I had in the initial years after his regression, that gave me many a sleepless night, was, would he ever acquire the skills he had lost and how long would that acquisition take? Over the years, I have made my peace with the initial regression and I have come to realize that literally NO one has an answer on how long it may take to re-acquire the skills that were lost, but consistent efforts can help the child acquire many a skill, in the long run.

WHAT DOES REASERCH SAY ON REGRESSION?
The internet has lots of information on Autism and regression, but many studies seem to point to a common factor, a process called Synaptic Pruning. Although the relationship between Synaptic Pruning and Regression is not very clear, Synaptic Pruning seems to play a significant role during the onset of the condition of Autism or when the signs of Autism become more visible to us.

WHAT IS SYNAPTIC PRUNING?
“Synaptic pruning is a natural process that occurs in the brain between early childhood and adulthood. During synaptic pruning, the brain eliminates extra synapses. Synapses are brain structures that allows the neurons to transmit an electrical or chemical signal to another neuron. Synaptic pruning is thought to be the brain’s way of removing connections in the brain that are no longer needed” (Accessed from the website https://www.healthline.com/health/synaptic-pruning).

Synaptogenesis (formation of synapses that allow neurons to communicate with each other, that in turn helps in the development of the brain) peaks around the ages of 2 and 3 (the toddler years). During this time, the brain also does a lot of pruning (removing of excess synapses that it considers to be unused /rarely used), to make way for newer neural connections.

One theory is that individuals with Autism, tend to have deficits in synaptic pruning, that leads to a lot of unnecessary synapses not being eliminated, thereby creating excessive synapses (especially dendritic spines), leading to informational /cognitive overload, abnormal brain connectivity and altered neural network functioning that can bring about changes in communication, social skills and stereotypical behaviours, that are a hallmark of Autism.

RESEARCH FINDINGS ON THIS SUBJECT:
In the study, Nishi, Y., et al. (2025). Impaired synaptosome phagocytosis in macrophages of individuals with autism spectrum disorder. Molecular Psychiatry. doi.org/10.1038/s41380-025-03002-3 , the following was cited, “A growing body of research suggests that neurobiological changes, particularly abnormalities in dendritic spines, tiny protrusions on nerve cells where synapses form, may be a hallmark of ASD. In particular, studies have found an unusually high number of these spines in individuals with autism. This overabundance of synaptic connections could disrupt normal communication pathways in the brain, potentially contributing to the behavioral and cognitive features seen in ASD”.

Autism spectrum disorders pathogenesis: Toward a comprehensive model based on neuroanatomic and neurodevelopment considerations
Athanasios Beopoulos 1, Manuel Géa 1, Alessio Fasano 2,3, François Iris
Front. Neurosci., 03 November 2022
Sec. Neurodevelopment
Volume 16 – 2022 | https://doi.org/10.3389/fnins.2022.988735

“Autism spectrum disorder (ASD) involves alterations in neural connectivity affecting cortical network organization and excitation to inhibition ratio. It is characterized by an early increase in brain volume mediated by abnormal cortical overgrowth patterns and by increases in size, spine density, and neuron population in the amygdala and surrounding nuclei. Neuronal expansion is followed by a rapid decline from adolescence to middle age. Since no known neurobiological mechanism in human postnatal life is capable of generating large excesses of frontocortical neurons, this likely occurs due to a dysregulation of layer formation and layer-specific neuronal migration during key early stages of prenatal cerebral cortex development. This leads to the dysregulation of post-natal synaptic pruning and results in a huge variety of forms and degrees of signal-over-noise discrimination losses, accounting for ASD clinical heterogeneities, including autonomic nervous system abnormalities and comorbidities” (an excerpt taken from the abstract of the study).

Loss of mTOR-Dependent Macroautophagy Causes Autistic-like Synaptic Pruning Deficits
Guomei Tang, Kathryn Gudsnuk, Sheng-Han Kuo …
September 17, 2014
https://www.cell.com/neuron/fulltext/S0896-6273(14)00651-5

“Developmental alterations of excitatory synapses are implicated in autism spectrum disorders (ASDs). Here, we report increased dendritic spine density with reduced developmental spine pruning in layer V pyramidal neurons in postmortem ASD temporal lobe. These spine deficits correlate with hyperactivated mTOR and impaired autophagy. In Tsc2+/− ASD mice where mTOR is constitutively overactive, we observed postnatal spine pruning defects, blockade of autophagy, and ASD-like social behaviors” (an excerpt taken from the summary of the study).

In conclusion, research on the link between Synaptic Pruning and Regression must be investigated further, but the association between Synaptic Pruning and onset of Autism seems to be quite clear. As with all things related to Autism, there is no clear-cut answer on the whys /causes of Regression, just yet. But it is hoped that in the years to come, there will be more clarity on this matter. 

But as parents and caregivers, we must take advantage of the possibilities that exist especially by understanding the nature of neuroplasticity and how brains can evolve with consistent efforts, over the years.
In my next blog, I will touch upon the topic of the Neuroplasticity of the Brain.

RESOURCES:
https://onlinelibrary.wiley.com/doi/full/10.1002/jnr.24616
https://www.news-medical.net/news/20250430/Study-links-impaired-synaptic-pruning-to-autism.aspx#:~:text=While%20previous%20postmortem%20and%20imaging,immune%20cells%20outside%20the%20brain.
https://www.cuimc.columbia.edu/news/children-autism-have-extra-synapses-brain
https://www.healthline.com/health/synaptic-pruning#an-indepth-look

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Author Dr.Triveni Goswami Vernal

Dr.Triveni Goswami Vernal is a Registered Special Educator (CRR: A64010), a Psychologist and an Expressive Arts Therapy Practitioner (UNESCO-CID). She is an Avaz Certified Educator and Certified in Dyslexia Teacher Training. She is also an art educator for children with additional needs.

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Nebula
Acrylic Painting on Ivory Paper
Kabir Vernal