Islamabad - Loss of sense of smell may indicate onset of some types of dementia, researchers say.

Previous research has associated olfactory loss, or anosmia, with cognitive decline, mild cognitive impairment (MCI) or Alzheimer’s disease (AD). It may also be a marker for Lewy body and vascular dementia.

Autopsy studies have linked a loss of ability to identify odors with the plaques and tangles in the olfactory bulb, entorhinal cortex and the cornu ammonis regions of the hippocampus.

Markers of early detection can help prevent or delay these diseases, and olfactory impairment may be an important clinical marker and predictor of these conditions, helping to identify those at risk.

Rosebud Roberts, of the Mayo Clinic in Rochester, MN, and coauthors assessed the sense of smell of 1,430 cognitively normal individuals, with an average age of 79.5 years; approximately half were men and half were women.

The participants were enrolled in the population-based, prospective Mayo Clinic Study of Aging between 2004 and 2010, and were clinically evaluated at baseline and every 15 months through 2014. The test they used involved six food-related and six non-food-related smells (banana, chocolate, cinnamon, gasoline, lemon, onion, paint thinner, pineapple, rose, soap, smoke and turpentine). Participants had to scratch, sniff and select one of four possible options, for a score to be computed.

Over an average of 3.5 years of follow-up, the authors identified 250 new cases of MCI among the 1,430 participants.

There was an association between a decreasing ability to identify smells - as measured by a decrease in the number of correct answers in the smell test score - and an increased risk of amnestic MCI (aMCI). There appeared to be no association between a decreased sense of smell score and nonamnestic MCI (naMCI), which can affect other thinking skills.

People with aMCI have memory problems more severe than normal for their age and education but not serious enough to affect daily life; naMCI is characterized by impaired thinking skills other than memory, such as trouble planning and organizing or poor judgment.

The authors also reported 64 dementia cases among 221 individuals with prevalent MCI. A decrease in the frequency of any or AD dementia was associated with increasing scores on the smell test. The worst smell test score categories were associated with progression from aMCI to AD dementia. The findings suggest an association between olfactory impairment, incidental MCI and progression from aMCI to AD dementia, and confirm previous studies linking olfactory impairment with cognitive impairment in late life.

Potential explanations for the current findings involve neurodegenerative changes in the olfactory bulb and brain regions that involve memory and sense of smell.

Coffee drinkers may live longer

Coffee lovers may live longer than those who don’t imbibe — with lower risks of early death from heart disease and neurological conditions such as Parkinson’s disease, a large U.S. study finds. Researchers said the study, adds to a large body of evidence on the good side of coffee.

People often think of coffee-drinking as a bad habit that they need to break, said study leader Dr. Frank Hu, a professor of nutrition and epidemiology at Harvard School of Public Health in Boston. But, Hu said, many studies have linked moderate coffee intake to lower risks of developing various diseases — from heart disease and diabetes, to liver cancer, to neurological diseases such as Parkinson’s, multiple sclerosis and Alzheimer’s.

His team’s study, funded by the U.S. National Institutes of Health, adds another layer of evidence. It found that coffee drinkers were not only less likely to develop certain diseases — they also tended to live longer. Over 30 years, nonsmokers who drank three to five cups of coffee a day were 15 percent less likely to die of any cause, versus nondrinkers. Specifically, they had lower rates of death from heart disease, stroke, neurological conditions and suicide.

Both regular coffee and decaf were linked to longer survival, the study found.

None of that proves coffee, itself, extends people’s lives or directly protects against certain diseases, Hu said. Other factors might explain the connection.

But, Hu added, his team did account for many of those factors. And the coffee benefit remained.

The findings are based on more than 200,000 U.S. doctors, nurses and other health professionals who were surveyed repeatedly over almost three decades. During that time, almost 32,000 study participants died.

It turned out that people who drank one to five cups of coffee at the outset had lower odds of dying during the study period when other lifestyle habits and certain health problems, such as high blood pressure and diabetes, were taken into account.

The relationship grew stronger when the researchers looked only at nonsmokers: Those who drank three to five cups of coffee a day were 15 percent less likely to die during the study period, compared with adults who didn’t drink coffee. Lower risks were even seen among the heaviest coffee drinkers (more than five cups a day), who had a 12 percent lower death risk than nondrinkers.

“The body of evidence does suggest coffee can fit into a healthy lifestyle,” Hu said.

That evidence, Hu noted, has already been incorporated into the latest U.S. dietary guidelines, which say that a healthy diet can include up to three to five cups of coffee a day.

But overall lifestyle is key, Hu said. That is, there’s a difference between a person who gets little sleep, then uses coffee to function during the day, and a person who sleeps well, exercises, and eats a balanced diet that includes some coffee.

Alice Lichtenstein, a spokesperson for the American Heart Association, agreed.

“This doesn’t mean you should start drinking coffee in the hopes of getting health benefits,” said Lichtenstein, who is also a professor of nutrition science and policy at Tufts University in Boston.