Montelukast May Induce Depression; Light Exposure May Increase Alzheimer's Disease Risk

Recently, the National Medical Products Administration issued an announcement (No. 120 of 2025) on revising the package inserts for montelukast preparations, requiring that warning language be added to the inserts of all montelukast formulations, alerting that montelukast carries a risk of inducing depression, self-harm, and suicide, and that patients should watch for neuropsychiatric adverse reactions.

Montelukast is a commonly used drug for allergic asthma and allergic rhinitis, developed by Merck & Co. of the United States. Montelukast is a leukotriene receptor antagonist that inhibits leukotrienes secreted by mast cells and basophils, thereby reducing allergic reactions. But in clinical use, some patients have developed emotional instability, self-harm, and suicidal behavior after taking montelukast. The US FDA has also issued a black-box warning for this drug, noting its neuropsychiatric adverse reactions.

Montelukast is a common medication for many patients with allergic asthma or allergic rhinitis, with annual sales in China exceeding one billion yuan. Many allergic asthma patients use it long-term, but previously they have not been aware of montelukast's damage to the nervous system.

Another study, published in Frontiers in Neuroscience, shows that light pollution also damages the nervous system and increases the risk of Alzheimer's disease (the most common form of dementia).

The study compared light-pollution levels across the 48 contiguous United States with local medical records and found a significant positive correlation between light pollution and Alzheimer's disease. Especially for people under 65, light pollution may be the single largest risk factor for Alzheimer's disease.

Researchers had 20 participants sleep in dimly lit rooms and in rooms with lights on, while monitoring their heart rates overnight. The results showed that participants who slept in lit rooms had faster heart rates, meaning their sympathetic nervous system was overtaxed; this may be why light pollution raises the risk of Alzheimer's disease.

We now know that drugs, light, radiation, toxins, viruses, and bacteria can all damage our nervous system and induce various nervous system diseases. Once the nervous system is damaged, repair and treatment are extremely difficult, so we must pay attention to prevention.