21 ways to reduce your Alzheimer's risk, backed by research

(CNN)There are 21 known ways to reduce your risk of developing Alzheimer's, and 10 of those are backed by strong scientific evidence, new research has revealed.

The preventative steps with the most impact are mentally stimulating activities, including reading and chess; avoiding stress, depression and head trauma; and avoiding diabetes, high blood pressure and weight gain in midlife and beyond, according to a meta-analysis released Monday.
Regular physical exercise, quality sleep, no smoking, maintaining good heart health in later life and including vitamin C in the diet are among the nine preventative actions with slightly weaker but still supportive evidence.
    "If risk factors can be modified, the evidence suggests that at least one out of every three cases of Alzheimer's may be preventable, " said neurologist Dr. Richard Isaacson, director of the Alzheimer's Prevention Clinic at Weill Cornell Medicine.
      "People can take different roads to Alzheimer's disease," said Isaacson, who was not involved in the study. "This paper helps to provide an evidence-based framework for doctors and patients to consider when managing a person's Alzheimer's risk."
        The study published in the Journal of Neurology, Neurosurgery & Psychiatry.

        Top-tier preventions

          Two-thirds of the most promising interventions focused on healthy lifestyle changes and targeting risk factors for cardiovascular disease, such as high blood pressure and cholesterol levels.
          The study analyzed 395 observational prospective studies and randomized controlled trials. These efforts, the researchers said, were the "most comprehensive and large-scale systematic review and meta-analysis for Alzheimer's disease to date."
          The top 10 preventative actions backed by science that the study found included:
          • Keeping blood sugars and weight in check to avoid diabetes
          • Maintaining weight at a healthy level, typically below a body mass index (BMI) of 25
          • Obtaining as much education as possible in early life
          • Avoiding head trauma (such as concussions)
          • Staying cognitively active by reading and learning new things
          • Avoiding or managing depression
          • Managing bad stress that raises cortisol levels
          • Treating "orthostatic hypotension" when you regularly feel light headed or dizzy when standing up from sitting
          • Keeping blood pressure under control in midlife
          • Avoiding high levels of homocysteine, an amino acid that can contribute to blood clots in your blood vessels and artery damage.
          "One of the most important and commonly overlooke