Somatostatin in the Brain Regulates Immune Cells to Fight Dementia, Study Finds

How Does Somatostatin Regulate Brain Immune Cells?

A team led by Professor Jiwon Um at DGIST's Center for Synapse Diversity and Specificity has identified a previously unknown mechanism by which somatostatin — a neuropeptide already known for its role in inhibiting growth hormone and regulating neurotransmission — directly communicates with microglia, the brain's resident immune cells. When activated by somatostatin signaling, these microglia shift away from a pro-inflammatory state that is widely recognized as a driver of neurodegeneration.

Microglia play a dual role in brain health: they clear cellular debris and pathogens, but when chronically activated, they release inflammatory cytokines that damage neurons and synapses. This chronic neuroinflammation is a hallmark of Alzheimer's disease and other dementias. The DGIST research demonstrates that somatostatin acts as a natural brake on this inflammatory cascade, suggesting that declining somatostatin levels — which have been observed in aging and Alzheimer's disease — may remove a critical protective mechanism against neurodegeneration.

Could Existing Drugs Be Repurposed for Dementia Treatment?

One of the most promising aspects of this discovery is that drugs targeting somatostatin receptors already exist and are used clinically. Somatostatin analogs such as octreotide and lanreotide are well-established treatments for conditions including acromegaly and neuroendocrine tumors. These drugs have known safety profiles and pharmacological properties, which could significantly accelerate the path from laboratory finding to clinical trial for dementia applications.

The research opens a new therapeutic avenue at a time when the field urgently needs it. According to the World Health Organization, dementia affects more than 55 million people globally, with nearly 10 million new cases each year. While recent anti-amyloid antibodies such as lecanemab have gained regulatory approval, they offer modest clinical benefit and come with significant side effects. A strategy targeting neuroinflammation through somatostatin pathways represents a fundamentally different and complementary approach that could work alongside existing therapies or benefit patients who do not respond to amyloid-targeting treatments.

What Does This Mean for Alzheimer's Disease Research?

For decades, Alzheimer's research was dominated by the amyloid hypothesis, which focused on the accumulation of amyloid-beta plaques as the primary cause of the disease. While amyloid clearly plays a role, the limited efficacy of amyloid-clearing therapies has pushed researchers to investigate other pathological mechanisms. Neuroinflammation has emerged as a critical factor, with multiple genetic risk factors for Alzheimer's — including variants in TREM2 and CD33 — directly linked to microglial function.

The DGIST team's work adds somatostatin signaling to the growing list of mechanisms that regulate microglial behavior in the context of neurodegeneration. Importantly, somatostatin levels are known to decline in the brains of Alzheimer's patients, particularly in the cortex and hippocampus — regions most affected by the disease. This correlation, combined with the new mechanistic evidence, suggests that restoring somatostatin signaling could help slow or prevent the inflammatory damage that contributes to cognitive decline. Future studies will need to determine optimal dosing, delivery methods to ensure the drugs reach brain tissue, and whether the benefits observed in preclinical models translate to human patients.