The researchers from Mount Sinai Medical Center in Florida, claim that the number of people who have Alzheimer's would be reduced if heavy smoking and drinking were reduced or eliminated.
The researchers also believe that a delay in the onset of Alzheimer's disease by five years would lead to a 50% drop in the number of cases.
The team led by Dr. Ranjan Duara say their findings showed heavy drinking and smoking were two of the most important preventable risk factors for the condition.
Those taking part in the study had been diagnosed with possible or probable Alzheimer's disease and their smoking and drinking history was obtained from family members.
Heavy drinking, defined as more than two drinks a day was found to lead to an almost five-year earlier onset of Alzheimer's and those who smoked more than 20 cigarettes a day developed the disease two years sooner.
Other research also revealed that people with a specific gene - APOE variant 4 - developed Alzheimer's disease three years earlier than those without the gene variant and people with high cholesterol in their early 40s were one and a half times more likely to develop Alzheimer's.
All three risk factors together were associated with onset of the disease 8.5 years earlier than those with none of the risk factors.
Experts say the research supports a body of evidence that shows drinking and smoking increase the risk of developing dementia.
They say the best way to reduce such a risk is to eat a balanced diet rich in antioxidants and vitamins, exercise regularly, not smoke and drink only in moderation.
They also stress the importance of regular checks for blood pressure and cholesterol throughout life.
Dementia is devastating for both the individual and their family and also places a huge burden on society and as many as 500,000 Australians are currently living with dementia.
The research was presented at an American Academy of Neurology.
Hippurate, another by-product of gut bacteria, was found in people with lower blood pressure who drink less and eat more fibre in their diet.
It is estimated that 1 billion people worldwide have high blood pressure, which is defined as a reading of 140/90 or higher.
High blood pressure or hypertension, is a major cause of stroke, heart disease and kidney failure and experts say a diet rich in vegetables and certain minerals along with regular exercise can help control high blood pressure.
The researchers say 'metabolic fingerprints' which are left behind after the breakdown of food and chemicals in the body, may well offer vital clues to the causes of disease.
Researcher Professor Paul Elliott, from the Department of Epidemiology and Public Health at Imperial College, says while a person cannot alter their DNA, they can change their metabolic profile by changing their diet and lifestyle.
The researchers hope their findings may lead to the development of new drugs to fight high blood pressure or possibly non-drug therapies.
The research is published in the current issue of the journal Nature.