Not that long ago, many people had a dim view of Down syndrome and the prospects for those diagnosed with this condition. Not only were these individuals expected to be severely intellectually delayed, but they were generally not expected to live independently or hold down jobs outside of sheltered workshops.
Today, however, our understanding of Down syndrome has changed to include a much more diverse view of the condition’s presentation, and people with the condition may get married, have children, go to college, and live otherwise fulfilling, self-directed lives.
What conditioned this change in how we understand Down syndrome? While there are a number of factors at play, among the most important is the fact that we better understand the neurological mechanisms behind intellectual disability in Down syndrome.
By looking beyond the basic cause – Trisomy 21 – as well as by meaningfully engaging with the work of disability rights advocates, our larger society has been able to change its view of people with Down syndrome and transform their long-term prospects.
Seeing The Big Picture
Part of managing Down syndrome has always involved looking at the co-occuring conditions that may be diagnosed alongside the disorder, the best known of which are heart defects that have historically led to shortened lifespans.
When we take a wider view, however, it quickly becomes clear that many of the other co-occurring conditions are neurological or cognitive in nature. These include major mental health issues, moyamoya syndrome, which involves problems in blood flow in the brain, autism and ADHD, and Alzheimer’s disease. Identifying these connections is key to understanding what is happening at a molecular and even structural level in the brains of people with Down syndrome.
For scientists exploring how Down syndrome works at a molecular level, one of the most powerful tools is a fruit fly model known as the Down syndrome cell adhesion molecule (DSCAM). This cellular model can also be applied in mice and, in high densities, can replicate the intellectual disabilities seen in Down syndrome.
Part of what is compelling about this model is that it offers insights into potential interventions for reducing the impact of these intellectual disabilities without fundamentally eliminating other traits that make Down syndrome a distinctive physical and developmental phenotype.
Other cellular insights from the world of Down syndrome research examine the increased prevalence of conditions like Alzheimer’s disease and autism in this population. The increase in Alzheimer’s cases has an obvious etiology – chromosome 21, which individuals with the condition have an extra copy of – carries the gene for amyloid precursor protein (APP), and amyloid plaques in the brain are one of the defining elements of Alzheimer’s.
As for autism, while the genetic basis is less immediately obvious, individuals with both conditions have synaptic irregularities, which points to some shared genetic basis that changes how the brain creates and maintains neuronal connections.
While changing the basic profile or presentation of those with Down syndrome shouldn’t be necessary in order to support their autonomy, endorse their competency to make medical decisions, and other major life choices, the fact remains that many will continue to treat people with Down syndrome this way barring a major change.
Ideally, that means providing autistic individuals with the self-advocacy skills they need to stand on their own, but offering meaningful medical interventions that enhance their underlying intellectual abilities is also a potential option, and one that could serve others with developmental or cognitive disabilities, as well.