Smoking and high blood pressure lead to the brain rotting faster, according to a new study from King's College, London. Researchers say that people who smoke need to make lifestyle changes to decrease risk of cognitive decline.

The study involved 8,800 people over 50 years old. Factors like overweight and high blood pressure were related to losing capacity to learn and remember things. Researchers found that smoking accelerated brain ageing.

Cigarette smoking alone causes more than 80 percent deaths due to lung cancer. Smoking is also associated with cancers of liver, bowel, pancreas, bladder and ovaries.

The study looked at the links between heart attack or stroke and the state of brain. Participants in the study took mental ability test that assessed the state of the brains.

Study results showed that participants with the highest mental decline were more likely to have a stroke or a heart attack than people who scored higher in the tests.

"Cognitive decline becomes more common with ageing and for an increasing number of people interferes with daily functioning and well-being. We have identified a number of risk factors which could be associated with accelerated cognitive decline, all of which, could be modifiable," Dr. Alex Dregan, one of the study authors, told BBC.

45.3 million people, or 19.3% of all adults (aged 18 years or older), in the United States smoke cigarettes, according to Centers for Disease Control and Prevention. Men are more likely to smoke than women. The agency also says that smoking kills an estimated 443,000 people, or 1 of every 5 deaths, in the United States each year.

"We all know smoking, a high blood pressure, high cholesterol levels and a high BMI [Body Mass Index] is bad for our heart. This research adds to the huge amount of evidence that also suggests they can be bad for our head too," Alzheimer's Society said, reports BBC.

Previous research has shown that people who don't smoke or quit smoking before 40 years of age have higher chances of living longer. Recently, one study had reported that for women, giving up smoking early can extend life by ten years.

"We need to make people aware of the need to do some lifestyle changes because of the risk of cognitive decline," Dergan added.

The study was published in the journal Age and Ageing.