QUESTION: Does using underarm deodorant increase the risk of developing Alzheimer's disease?
ANSWER: Alzheimer's disease is a devastating disorder of the human brain resulting in the cardinal symptom of memory loss that impairs a person's ability to carry out important day-to-day functions such as cooking, shopping, managing finances, performing at work and maintaining social relationships.
It is most commonly a disease of the elderly, and advancing age is the strongest known risk factor for the development of this disorder. The cost to individuals, their families and society is high, with an anticipated increase in the number of Alzheimer's cases in upcoming years due to the aging baby boomer population.
In addition to aging, the same risk factors for heart attack and stroke - high blood pressure, elevated cholesterol, diabetes, obesity and smoking - predispose one to Alzheimer's disease.
There are many protective factors that can reduce the risk of developing this disorder, including higher educational attainment, regular exercise, healthy diet and lifestyle, and healthy social relationships.
What causes Alzheimer's disease? The answer to this question is elusive and still under active investigation, but starts with an understanding of the nature (what you are born with) versus nurture (what you experience or are exposed to) paradigm.
Genetics, the study of heritable traits passed down from one generation to the next, is involved on the side of nature. Uncommon abnormalities or mutations in three identified genes can cause rare forms of Alzheimer's disease that run strongly in families. Other genetic aberrations may increase risk for developing the disease. The nurture, or environmental, side of the story is even more complex to study.
One of the suspected environmental risks for the development of Alzheimer's disease, which has been highly controversial in the scientific literature, is lifelong exposure to high levels of aluminum. Exposure may come through many sources, including drinking water, cooking with aluminum pots and pans and use of antiperspirants. Most antiperspirants contain aluminum salts, and there is a potential risk that aluminum may be absorbed through the skin of the armpit, resulting in ultimate accumulation of high levels of this metal in the brain.
Studies of brain tissue in the test tube or in animals have shown that aluminum in high concentrations can be toxic to nerve cells. This type of research, which is many steps away from the true human condition, has been supported by comparisons of brains from patients who have passed away from Alzheimer's disease to those of individuals who have died from other conditions.
Specifically, aluminum levels were found to be higher in Alzheimer's brains than in non-Alzheimer's brains. However, many large studies of populations exposed to drinking water containing high and low levels of aluminum have demonstrated inconsistent results and were inconclusive in proving aluminum as an independent risk factor for the development of Alzheimer's disease.
The Canadian Study of Health and Aging did not demonstrate a link between antiperspirant use and risk for developing Alzheimer's disease. Currently, there is no strong scientific basis to support the premise that aluminum, in the particular form contained in antiperspirants, can cause or increase risk of Alzheimer's disease.
Therefore, based on our current state of knowledge, discontinuing antiperspirant use is not recommended to reduce the risk of developing Alzheimer's disease.
The best bang for your buck to reduce the risk of developing this devastating disorder will be to maintain a regular exercise routine, a healthy diet, and be engaged in socially and mentally stimulating activities.
Furthermore, aggressive management of cardiovascular risk factors including controlling blood pressure, reducing your cholesterol, treating diabetes, losing weight and stopping smoking could also be critical to prevention.
Mario Masellis is a neurologist and scientist specializing in the diagnosis, treatment and research of Alzheimer's disease and related conditions at Sunnybrook Health Sciences Centre and the University of Toronto.