How to treat nervous system disorders

Research is beginning to unravel the biological causes of neurodevelopmental disorders. These laboratory findings are being translated into the development of new drugs being tested in human clinical trial studies. While these studies have yet to be completed, the preliminary results are promising.

A common theme across pre-clinical and clinical studies is that the patient’s situation improves the earlier the treatment starts. In neurodevelopmental disorders, the disease starts early and evolves through an individual’s lifetime. Therefore the neurobiological consequences of the disease worsen with age to the point where the damages can be irreversible beyond a certain stage. For instance in studies of spinal muscular atrophy, a developmental neurodegenerative disorder that causes paralysis, treatments confer therapeutic benefits only when they are administered in the pre-symptomatic stage (the time before the disease clinically manifests).

Therefore the ideal solution is to diagnose and begin treatment early.

While it is no surprise that earlier is better, the majority of the patient population belongs in the post-symptomatic stage. Neurodevelopmental disorders often do not present obvious symptoms at birth and are therefore not diagnosed until several years into disease progression, when major symptoms begin to show up. Research highly suggests that treatments only work when they are delivered early. But is it too late for individuals with neurodevelopmental disorders to receive treatments, given that the majority of them have passed the window of therapeutic opportunity?

The answer might depend on the disorder. For some specific diseases, reversal of disease pathologies in adult animal models has been demonstrated, which suggests hope for late treatment onset.

For diseases that have a strict window of opportunity, we have to be realistic and cannot expect miracle cures. However that does not mean any treatment effort in late stages of the disease is futile. The goal here should not be a cure. Instead we need to focus efforts on ways to potentially slow down the progression of the disease or prevent further loss of brain function.

Let’s consider the case of neurodegeneration. It is extremely difficult to regenerate new neurons once they are dead. Although there are efforts to develop stem cell based strategies that offer hopes of at least partial regeneration, such efforts are still far from clinical realities. However we also have to remember that there is not a 100 percent neural loss: Some neurons do survive. Therefore treatment strategies should primarily be guided by efforts to prevent further neural loss.

There is also evidence that the still surviving neurons do make attempts to compensate for neural loss. As a result, helping to make the still surviving neurons work better may also contribute towards slowing down disease progression and perhaps even partially recovering some brain function.