What are the side effects of smoking on the nervous system?

Side Effects of Smoking on the Nervous System

Smoking has significant detrimental effects on the nervous system, including increased risk of stroke, neurocognitive impairment, and alterations in brain structure and function. 1

Cerebrovascular Effects

• Smoking approximately doubles the risk of ischemic stroke, with a relative risk of 1.8 after adjusting for other risk factors 1
• Smoking increases the risk of subarachnoid hemorrhage (SAH) by 2-4 times compared to non-smokers 1
• The relationship between smoking and intracerebral hemorrhage (ICH) is less consistent, with some studies showing an association and others not 1
• Smoking potentiates the effects of other stroke risk factors, creating synergistic effects - particularly when combined with oral contraceptive use, which increases stroke risk by 7.2 times compared to non-smoking women who don't use oral contraceptives 1
• The pathophysiological mechanisms include reduced blood vessel distensibility, increased arterial wall stiffness, and alterations in blood rheology 1

Neurobiological Effects

• Nicotine affects numerous neurotransmitter systems including acetylcholine, norepinephrine, serotonin, and dopamine, influencing a wide range of cognitive functions 2, 3
• Smoking causes neuroendocrine effects including release of arginine vasopressin, beta-endorphin, adrenocorticotropic hormone, and cortisol 3
• Nicotine affects neuroregulation and causes structural changes in the brain that can disturb reflexes and responses, potentially increasing vulnerability to hypoxia 1
• Nicotine addiction may cause deleterious effects in women's brains by inhibiting estrogen signaling, potentially making the brain more susceptible to ischemia 1

Cognitive Effects

• Acute nicotine exposure can temporarily improve certain cognitive functions including attention and memory, which reinforces continued smoking behavior 2
• However, chronic heavy smoking is associated with cognitive impairment and accelerated cognitive decline in middle age 2, 4
• Smoking affects multiple cognitive domains including sensorial processing, motor function, attention, executive function, learning, and memory 2, 4
• Smoking is associated with preclinical brain changes including silent brain infarcts, white matter hyperintensities, and brain atrophy 4

Neurodegenerative Disease Risk

• The relationship between smoking and neurodegenerative diseases is complex 5, 4
• Some epidemiological studies have found a negative association between smoking and Parkinson's disease and Alzheimer's disease, suggesting smokers may have approximately half the risk compared to non-smokers 5
• However, recent evidence suggests medicinal nicotine may potentially catalyze processes underlying neuropathology in Alzheimer's Disease 4
• Potential mechanisms for smoke's harmful neurological effects include oxidative stress, inflammation, and atherosclerotic processes 6, 4

Smoking Cessation and Neurological Health

• Smoking cessation is associated with a rapid reduction in stroke risk, with risk decreasing by 50% within 1 year and approaching baseline after 5 years 1
• Effective smoking cessation approaches include combination nicotine replacement therapy (NRT) or varenicline as primary therapies 7
• Neuropsychiatric side effects should be monitored when using varenicline or bupropion for smoking cessation 1
• Abstention from smoking by non-smokers and smoking cessation by current smokers is strongly recommended based on the overwhelming evidence of smoking's relationship with stroke and other neurological conditions 1

Special Considerations

• Passive exposure to environmental tobacco smoke may also increase stroke risk, with some studies suggesting the risk approaches that of active smoking 1
• The effects of nicotine on the developing brain are particularly concerning, with evidence of adverse effects on neurodevelopment 1, 4
• Cigarette smoke contains over 4,500 toxic chemicals that form free radicals, leading to oxidative stress-associated neurological disorders 6