Eat right, lose weight and exercise to help control high blood sugar and cognition.

Take action against Insulin Problems that can impair your memory

Scientists are uncovering increasing evidence that abnormal blood sugar levels and insulin resistance – a condition in which the body’s cells stop responding normally to insulin – may not only lead to conditions such as diabetes (a serious condition which in turn can lead to heart disease, nerve damage and kidney problems), but also may be responsible for brain changes manifested as impaired learning and memory.

However, controlling blood sugar levels and reducing insulin resistance with such strategies as weight control, regular exercise and healthy low fat diet may help you avoid the damaging processes that can increase the risk for illness, cognitive decline and dementias. Dementias are a group of disorders characterized by severe memory problems that include Alzheimer’s disease (AD).

“Research suggest that people whose blood sugar levels are poorly controlled and whose insulin metabolism is impaired are more likely to have cognitive problems and may have a higher risk of dementia and depression, although the exact mechanisms involved in this associations are not yet clear” says Dan V. Iosifescu, MD, MSc, Director of Translational Neuroscience at Massachusetts General Hospital (MSG).

“Learning more about the way insulin and blood sugar levels act on the brain and the role they play in dementias may help us devise better treatments for memory disorders.”

High blood sugar levels can directly affect the hippocampus, a brain region responsible for memory and learning, according to a study published in the December 2008 issue of Annals of Neurology. Researchers used functional magnetic resistance imaging (fMRI) to map the hippocampus in 240 older adults without apparent memory problems. They found that, unlike other study participants, the 60 participants with type 2 diabetes showed evidence of damage to the “dentate gyrus”, a sun region of the hippocampus associated with are related memory decline, suggesting the blood sugar abnormalities were implicated in hippocampal dysfunction. The study’s authors concluded that because blood sugar levels rise with age, even people without diabetes would benefit from strategies to improve blood sugar levels as a way to preserve cognitive function.

Defining Insulin Resistance
Insulin is a hormone secreted by cells within the pancreas in response to higher levels of glucose (blood sugar) that result when food and drink are digested. It normally helps lower blood sugar levels by facilitating the movement of glucose from the blood stream into the body’s cells, where it is used for fuel. But lack of exercise, excess weight, or other factors can lead individuals to develop insulin resistance, in which the body’s cells gradually fail to respond normally to insulin and glucose remains in the blood stream.

As glucose levels mount in the blood stream, the pancreas attempts to compensate for insulin resistance by supplying larger and larger amounts of insulin in order to provide energy for the body’s cells. Eventually, the organ may be unable to keep up with the need for insulin, and blood sugar levels rise. Without adequate treatment, blood sugar levels may continue to mount in a proce3ss that starves body cells of fuel, impairs their functioning and eventually damages or kills cells. (The CDC reports that the number of people with diabetes has increased at an alarming rate from 6 million in 1980 to 16 million in 2005.)

When the body cannot supply enough insulin or respond to insulin normally, type 2 diabetes or metabolic syndrome (a constellation of symptoms that include high blood pressure, elevated waist circumference, low HDL “good” cholesterol and elevated levels of triglycerides, a type of blood fat) may ensue.

Insulin’s role in the brain
Insulin is thought to be critical to proper brain functioning. Research suggests the hormone facilitates learning and memory by binding to receptors at the synapses (communication points between neurons) and enabling the formation of memories. A recent study indicates it also may play an important role in the formation and maintenance of neural networks along with signals flow from cell to cell, helping to keep the brain “plastic” and responsive to new information.

People with AD characteristically have disrupted insulin function at the synapses and reduced brain plasticity.

The central role of insulin in memory formation means that abnormal insulin metabolism and high blood sugar levels associated with metabolic syndrome or diabetes may have severe consequences for memory. Among the ill effects suggested by research are:
• Damage to cerebral blood vessels. Diabetes causes damage to blood vessels in many areas of the body, including the brain. The damaged cerebral blood vessels lead to poor oxygen and nutrient flow to multiple areas of the brain, a condition which can lead to vascular dementia, depression or brain atrophy. Risk for stroke and cognitive decline is significantly increased.
• Pro-inflammatory processes, which have been linked top increased risk of dementias such as AD. Inflammation has been implicated in increased formation of plaques and tangles associated with AD, and the generation of unstable oxygen molecules called free radicals that can damage neurons.
• Increased accumulation of beta-amyloid plaque, a key characteristic of Alzheimer’s disease. Both insulin and amyloid plaque are degraded by the same enzyme, insulin degrading enzyme (IDE). The competition for IDE from higher levels of insulin may lead to greeter accumulation of toxic beta-amyloid in the brain.
• Slowed executive functioning and speed of response. Tests show that people with diabetes may be more likely to have trouble with executive functions, such as working with new information to solve problems, focusing or giving thoughtful answers to questions, and may be slower to respond to mental challenges.
• Excessive levels of stress related hormone corticosterone. Chronic exposure to high levels of stress hormones is associated with damage to the hippocampus, which in turn manifests as memory and learning problems.
• Increased risk of developing Alzheimer’s disease. A number of studies suggest that people with type 2 diabetes are at greater risk for AD. Swedish research conducted in 2007 found that older adults conducted in 2007 found that older adults with borderline diabetes were nearly 70 per cent more likely than people without insulin problems to develop AD.

Summary: What you can do
Taking these practical measures may help you avoid memory problems associated with insulin and blood sugar abnormalities:
• Eat a healthy diet. Consume a diet with plenty of whole grains, fresh fruits and vegetables, fish and low fat dairy products and meats. Avoid saturated and trans fats as much as possible along with sweets, syrups and refined grains that can boost blood sugar levels. Get plenty if fibre to help lower insulin and cholesterol levels. Watch your calories.
• Maintain a healthy weight. Ask your doctor what is a healthy weight for someone of your height and age. If you have trouble keeping your weight down, ask your doctor to recommend a weight-loss strategy or program.
• Exercise regularly. Exercise helps make body cells more sensitive to insulin. Try to get 30 minutes a day or more of moderate exercise at least 5 days a week.
• Get adequate sleep. 7 to 8 hours a night are sufficient for most people.
• Have regular medical assessments. Ask your doctor to test your fasting blood sugar levels and your cholesterol levels for signs of insulin problems. Eye exams can also help detect early vascular changes related to diabetes.

Your Health and Mine