Diabetes Among Risk Factors For Dementia

By Dace Trence, MD, FACE

Many of us are concerned about the possibility of developing Alzheimer’s disease or another type of dementia as we grow older. The prospect can be of particular concern for those who have witnessed a family member, friend or colleague undergo a devastating loss of thinking skills and memory or have been a caregiver to a loved one going through this ordeal.

And while the steady decline of brain function seen in these diseases cannot be avoided—Alzheimer’s disease is incurable and is now the sixth leading cause of death in the U.S. according to the CDC—there is one scenario in which a person may be able to reduce their risk of developing dementia: keeping blood sugar under control if you have diabetes.

Dementia is an overall term for diseases and conditions characterized by a decline in memory or other cognitive abilities that affect a person’s ability to function normally. It’s caused by damage to nerve cells in the brain called neurons. When neurons are damaged, they can no longer function normally and die, which in turn leads to changes in memory, behavior and the ability to think clearly.

Several research studies following large groups over many years have suggested an association between diabetes and dementia when the blood sugar is out of control, and recent studies support this finding.

Research results presented this fall at the European Association for the Study of Diabetes (EASD) produced evidence that high blood glucose levels increase the risk for dementia in individuals with type 2 diabetes (the diabetes that is the result of insulin not working as it should combined with less insulin produced over time). But the very good news was that better blood sugar control might just prevent such thinking and memory decline.

Study researchers followed approximately 350,000 people with type 2 diabetes (2DM) from the Swedish National Diabetes Registry between 2003 and 2012. The study participants did not have dementia at the start of the study period and were followed for an average period of almost five years. The participants were divided into seven groups based on individuals’ baseline HbA1c, a blood test that measures long-term control of blood sugar levels.

In examining the possible association between dementia and blood sugar control, researchers identified possible additional risk factors, complications and associated medical conditions, as well as medication use, to eliminate contributing factors that could impact the results related to just blood sugar control alone.

Study results suggested that there were no dementia risk levels at an HbA1c level of 6.7 percent, but that higher A1c levels in excess of 10 percent increased the rate of dementia from 23 percent to 77 percent. Thus, blood sugar control is a powerful protector. Not surprisingly, dementia risk also increased with old age, increased diastolic blood pressure (the lower number on blood pressure measurement) and elevated low-density lipoprotein cholesterol (LDL cholesterol is the high-risk heart disease cholesterol). Being overweight or obese and being a smoker are additional risk factors.

Having had a stroke increased the risk for dementia by 43 percent, but the presence of atrial fibrillation (an irregularity of heart rhythm), or coronary heart disease (heart vessel disease) caused little risk increase. Also, those patients who developed microalbuminuria (moderately increased protein in the urine) or macroalbuminuria (a lot of increased protein in the urine) also had a higher risk for dementia than those without albuminuria.

Those who did not perform any daily physical activity versus those who did had a higher dementia risk, so exercise made a significant difference in protecting against cognitive problems.

And the use of blood pressure control medications and statin medication—a specific class of drugs that decrease blood cholesterol levels—also protected against the development of dementia.

What can you do to reduce your risk?

Keep your blood sugars under control. Talk with your diabetes healthcare team about your personal blood sugar targets, what is ideal and what would be acceptable. Discuss in detail specific steps that would help you reach those goals, ranging from changes in your daily physical activity level to changes in your meal intake choices and medication. Review your blood pressure control targets. Is your blood pressure at target goal? If not, what steps can be taken to reach that goal, such as medication? Also, is your blood cholesterol under control? These are all issues to examine.

What about other approaches?

There are studies suggesting that taking a low-dose aspirin every day may lower the risk of heart attacks for some people with diabetes—men over 50 and women over 60 years old with other risk factors such as high blood pressure or high cholesterol. Aspirin has been shown to help those with diabetes who have had a heart attack or a stroke or who have heart disease. But if you have not had a heart attack or a stroke, aspirin may not be as risk-free and safe. You should ask your healthcare team whether you should take aspirin, as there is increased risk of bleeding with aspirin intake, especially as you age and have not had a vascular event. Even a dose of 81 milligrams (considered a low dose or “baby aspirin”) can be associated with a bleeding risk, such as a stomach ulcer. Benefits and risks have to be considered, with the objective of benefits clearly outweighing risk. See more at: http://www.diabetes.org/living-with-diabetes/treatment-and-care/medication/other-treatments/aspirin.html#sthash.dXQQndMp.dpuf

While the association between dementia and diabetes is clear, researchers still don’t fully understand the mechanism of how diabetes triggers dementia. Until that connection is understood, awareness of that link could help people realize further how important it is to manage their diabetes and help motivate them to do so to reduce their risk.

Dr. Dace Trence is Director of the Diabetes Care Center and Professor of Medicine at the University of Washington Medical Center in Seattle. She is also the University of Washington Endocrine Fellowship Program Director and Director of Endocrine Days, a medical education program for endocrinologists practicing in the Pacific Northwest. She is on the American College of Endocrinology Board of Trustees and chairs the CME Committee and is also chair of the AACE Publications Committee.