The Surgeon General first raised the alarm about the dangers of cigarette smoking 50 years ago. Since then, the tobacco habit has continued to kill 20 million Americans, according to a recent government report. Smoking has been long linked to a myriad of health problems, from lung cancer and heart disease to chronic obstructive pulmonary disease and certain birth defects. Evidence has accumulated in recent years indicating tobacco hits the brain hard, too.
For example, smokers tend to have more memory problems in later life than non-smokers. King’s College London researchers studied nearly 9,000 people age 50 and older, looking for links between memory problems and smoking, high blood pressure, cholesterol levels, and body mass index (BMI). The results, published in the journal Age and Aging, showed that, while all the factors studied took a toll on brainpower, smoking had the biggest impact. Smokers consistently scored lowest on three objective memory tests that measured attention, mental speed, and visual scanning.
Several studies have associated smoking with an increased risk of outright dementia, too. Deborah Barnes, a mental health researcher at the San Francisco VA Medical Center, estimates that nearly 14 percent of Alzheimer’s disease cases worldwide could be attributable to smoking, one of several modifiable risk factors known to influence that dreaded disease.
“What’s exciting is that this suggests that some very simple lifestyle changes, such as increasing physical activity and quitting smoking, could have a tremendous impact on preventing Alzheimer’s and other dementias in the United States and worldwide,” said Barnes, an associate professor of psychiatry at the University of California, San Francisco (UCSF).)
By contributing to cardiovascular disease, smoking is known to raise the risk of blood clots that cause brain-damaging and potentially deadly strokes. Research published in the New England Journal of Medicine shows that smokers are twice as likely to die of stroke, also known as a “brain attack,” compared to non-smokers.
Scientists at the National Brain Research Center (NBRC) in India have found that a compound known as NNK in tobacco may trigger brain cell damage. NNK causes inflammation by provoking immune cells in the central nervous system to attack healthy brain cells. According to preliminary research published in the Journal of Neurochemistry, this neurological damage could play a role in causing diseases that affect the brain, including multiple sclerosis.
Research recently published in the journal Molecular Psychiatry has found new evidence that long-term smoking causes the brain’s cortex, the outer layer where critical functions such as memory, language, and perception take place, to thin. This is worrisome because a decline in thinking ability is associated with a shrinking cortex. While age alone causes some thinning of this part of the brain, the process is clearly accelerated in smokers.
Researchers from Montreal Neurological Institute at McGill University and the University of Edinburgh’s Center for Cognitive Aging and Cognitive Epidemiology studied 244 men and 260 women, all of them elderly. Some were current smokers, some had never smoked, and others had quit smoking in the past. MRI scans documented the size and thickness of the research subjects’ brain cortices.
“We found that current and ex-smokers had, at age 73, many areas of thinner brain cortex than those that never smoked. Subjects who stopped smoking seem to partially recover their cortical thickness for each year without smoking,” the study’s lead author Sherif Karama, assistant professor of psychiatry at McGill University, said.
However, that didn’t mean that quitting smoking allowed brains to recover quickly – or completely. MRIs revealed that even after quitting cigarettes over 25 years ago, those research subjects who had once been heavy smokers still had thinner cortices than those who had never smoked.
“Smokers should be informed that cigarettes could hasten the thinning of the brain’s cortex, which could lead to cognitive deterioration. Cortical thinning seems to persist for many years after someone stops smoking,” Karama said.
The researchers concluded that the sooner a smoker stops lighting up, the better odds are the brain can recover. Their findings suggest that the cortex can regain a healthier thickness in as little as a few weeks after smoking cessation – or, depending on the amount a person smoked in a lifetime, it could take more than a theoretical (and impossible)140 years.
Bottom line: It’s a no-brainer that anyone who is still smoking should quit. You have many options to help you quit. The National Heart, Lung and Blood Institute also offers information on strategies that are proven to help with smoking cessation, from medication to how to find support and deal with relapses.
March 25, 2015
Christopher Nystuen, MD, MBA