Smoking and Neurodegeneration: The Lung-Brain Link to Dementia

Research from the University of Chicago published April 9, 2026, in Science Advances has identified a previously unmapped biological pathway, termed a lung-brain axis, that links nicotine exposure to neurodegeneration.

The study suggests that nicotine triggers a specific communication process between the lungs and the brain, providing a potential explanation for why cigarette smoking is associated with cognitive decline and an increased risk of dementia.

The Mechanism of the Lung-Brain Axis

The researchers identified that pulmonary neuroendocrine cells, known as PNECs, located in the lungs play a central role in this process. When these cells are exposed to nicotine, they release exosomes, which are small vesicles that transport molecular signals.

Once these exosomes reach the brain, they disrupt iron homeostasis within neurons. This perturbation of the iron balance triggers symptoms frequently observed in patients suffering from dementia.

This research establishes a clear ‘lung-brain’ axis that helps explain why cigarette smoking is linked to cognitive decline and neurodegenerative risks

Kui Zhang, UChicago postdoctoral researcher and co-first author

According to Zhang, understanding how these exosomes affect iron balance may lead to new methods for protecting neurons from the damage induced by smoke.

Shifting Theories on Smoking and Dementia

Historically, the link between smoking and neurodegeneration has been attributed primarily to the impact of tobacco on the respiratory and vascular systems. These theories suggested that smoking effectively choked the flow of oxygen to the brain over several decades of use.

Other established factors include toxins in cigarette smoke that cause cellular stress and inflammation, both of which are linked to Alzheimer’s disease. Vascular problems involving the heart and blood vessels are also closely associated with the two most common forms of the condition: vascular dementia and Alzheimer’s disease.

The discovery of the lung-brain axis provides a distinct biological route for damage that operates alongside these vascular and inflammatory processes.

Long-term Risks and the Impact of Smoking

The correlation between smoking and neurodegeneration is well-documented in medical literature. One study from 2011 found that heavy smoking during midlife was associated with a greater than 100% increase in the risk of developing Alzheimer’s, vascular dementia, and general dementia more than two decades later.

Researchers have noted that dementia is often a less-studied impact of smoking because it typically manifests later in life, while many smokers tend to die younger.

Risk Reduction and Cessation

Evidence indicates that the risk of developing dementia can be mitigated by stopping smoking. According to the Alzheimer’s Society, stopping smoking is thought to reduce a person’s risk to the level of those who have never smoked.

While it remains unclear exactly how long a person must be smoke-free to eliminate the increased risk, research suggests that the earlier an individual quits and the longer they remain smoke-free, the greater the benefit.

This pattern of risk reduction is similar to the way smoking cessation reduces the likelihood of developing cancer or cardiovascular disease.