Chemistry plays a fundamental role in human mental and psychological health, as chemical interactions in the brain regulate emotions, behavior, cognition, and the ability to adapt to daily challenges. Neurotransmitters are essential chemical compounds that transmit signals between nerve cells, with the most prominent being: Serotonin: Responsible for regulating mood, appetite, and sleep; its deficiency is associated with increased depression and anxiety. Dopamine: Involved in the sensation of pleasure and motivation, contributes to attention and movement control; its imbalance is linked to mood disorders and Parkinson’s disease. Norepinephrine: Contributes to stress response and attention; any imbalance can lead to concentration difficulties or anxiety disorders. Chemical interactions in the brain are influenced by multiple factors, including nutrition, physical activity, sleep, psychological stress, and exposure to external chemical substances. For example, deficiencies in certain vitamins and minerals, such as Vitamin B6, magnesium, and zinc, can reduce neurotransmitter production, increasing the likelihood of anxiety and depression symptoms. Chemistry also plays a central role in the development of psychotropic medications, where antidepressants work by increasing serotonin and norepinephrine levels in the brain, while anxiolytic drugs help calm excessive neurotransmitter activity to reduce psychological stress. Recent research in neurochemistry focuses on understanding molecular interactions in the brain to design more effective treatments with fewer side effects. Moreover, chemistry provides a scientific explanation for the relationship between environmental factors and human behavior. Exposure to chemical pollutants, such as lead or mercury, can affect neurotransmitter function, causing behavioral or cognitive disorders, which underscores the importance of a healthy environment in supporting mental health. In conclusion, it is evident that chemistry is not merely the study of compounds and substances but a foundation for understanding human mental and psychological health. Maintaining chemical balance in the body and brain is essential for emotional and psychological well-being, highlighting the crucial role of ongoing chemical research in developing therapeutic and scientific strategies to improve the quality of human life. Al-Mustaqbal University Ranked First Among Private Universities in Iraq