The Role of the Complement System in Neurodegeneration

🕒 Approximate reading time: 4 minutes

The complement system is an integral part of our immune response, responsible for enhancing the abilities of antibodies and phagocytic cells to clear microbes and damaged cells. However, recent research has started to uncover a more sinister side to this system when it comes to the brain. This blog post delves into the potential role of the complement system in neurodegenerative diseases.

Understanding the Complement System

The complement system is a complex network of proteins, produced by the liver and released into the bloodstream, that 'complement' the work of antibodies and phagocytic cells to eradicate pathogens. These proteins work in a cascade, where one activates another, to achieve their goal.

The Complement System and Neurodegeneration

While the complement system is necessary for a healthy immune response, its role in the brain and its contribution to neurodegeneration is complex. It's been found that many proteins of the complement system are present in the brain, but their levels increase significantly during neurodegenerative diseases like Alzheimer’s disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS).

Evidence shows that the complement system may contribute to the loss of synapses, the junctions between neurons that facilitate communication. This synaptic loss is a common feature of many neurodegenerative diseases and can lead to widespread neuronal death.

Complement proteins can mark synapses for destruction by tagging them as if they were foreign bodies. In the healthy brain, this process helps prune unnecessary synaptic connections during development. However, in neurodegenerative conditions, this system appears to go awry, resulting in the excessive loss of synapses and contributing to disease progression.

Therapeutic Potential

Understanding the role of the complement system in neurodegeneration opens a new window for potential therapies. If the complement system is indeed contributing to neurodegeneration, it might be possible to develop treatments that can inhibit this harmful action without compromising its beneficial immune functions.

Several experimental drugs are currently being tested in preclinical and clinical trials, aimed at inhibiting specific components of the complement cascade. The hope is that these treatments may slow down or even halt the progression of neurodegenerative diseases.


Research on the role of the complement system in neurodegeneration is still in its early stages, and much remains to be discovered. However, the potential therapeutic implications of this research are promising, offering hope for future treatment strategies for neurodegenerative diseases.