A study by researchers at the Albert Einstein College of Medicine in New York and the Montefiore Health System followed 507 people enrolled in the Einstein Aging Study, a group of adults aged 70 or older who live in the Bronx borough of New York.

The volunteers underwent neuropsychological tests, clinical evaluations, examinations of medical histories and evaluations of daily activities.

The participants also had their stress levels evaluated by the researchers using the Perceived Stress Scale (PSS). The volunteers were given scores from zero to 56, with higher numbers indicating increased levels of perceived stress. They were tracked for an average of 3.6 years.

The findings – published in the journal Alzheimer's Disease and Associated Disorders – showed that those in the highest quintile of five PSS tiers were found to be two-and-a-half times more likely to develop mild cognitive impairment, which is often a precursor to Alzheimer's disease.

The study also found that for every five points a person scored under the Perceived Stress Scale, the risk of cognitive impairment increased by 30 percent.

"Our study provides strong evidence that perceived stress increases the likelihood that an older person will develop [amnestic mild cognitive impairment],” lead researcher Dr. Richard Lipton said in a press release.

However, study author Mindy Katz noted that perceived stress and the risks associated with it can be “altered by mindfulness-based stress reduction, cognitive-behavioral therapies and stress-reducing drugs,” adding that “these interventions may postpone or even prevent an individual’s cognitive decline.”

Meanwhile, a separate body of research, the Danish Alzheimer's Intervention Study (DAISY), has concluded that moderate alcohol consumption can lower the risk of dying from the disease.

The study, published in the journal BMJ Open, analyzed data collected on 330 people with early stage dementia or Alzheimer's and their primary carers, all of whom resided in Denmark. That data included information on how much alcohol each person drank every day.

The researchers determined that consumption of two to three units of alcohol each day was associated with a 77 percent lower risk of death compared with one or fewer daily units, after analyzing data from the 53 individuals with mild Alzheimer's disease who died during the study. The results held true when other factors – including age, gender, other underlying conditions, education, quality of life and living situation – were taken into effect.

The scientists said there could be several explanations for the findings, including that people who drink moderately have a richer social network, which has been linked to improved quality – and possibly length – of life.

Another explanation was the potential for reverse causality, meaning that those drinking very little alcohol were already in the terminal phase of their life – which would have artificially associated the positive effect of alcohol in patients.