Ask the Doctors

Dear Doctor: I recently saw a TV show in which a physician said sweets cause dementia. Is this true? As a sweet-aholic, I hope not.

Dear Reader: How I used to love sugar as a child. My parents didn't have many sugary foods in the house, so I would gorge on sweets at my friends' houses or when the ice cream man made his rounds. At age 11, however, I began to understand the health consequences of sucrose -- I knew that it increased the risk of diabetes and was directly connected to weight gain. I learned much later about the less tangible dangers -- metabolic changes, heart disease risk and a potential link to cancer.

Many people, however, continue to indulge in sweets well into old age. While some can do so with relative control, others cannot. The problem for everyone is that, as we grow older, our ability to process sugars declines, leading to an increased risk of obesity and diabetes, among other things.

The dementia connection has to do with how our brains receive nutrients and oxygen. While many large blood vessels supply blood flow to the brain, equally important are the small blood vessels that nourish the neurons. Small blood vessels are quite susceptible to injury, especially those caused by high blood pressure and diabetes. That's why people with poorly controlled diabetes are at risk for slow-to-heal ulcerations: The small vessel disease in the lower legs leads to poor blood flow and nerve dysfunction. Similarly, poorly controlled diabetes can also lead to small blood vessel disease in the brain and the death of neurons. Multiple epidemiologic studies have shown a correlation between diabetes and dementia, as have MRI studies in animals.

I'm sorry to add that, even if you're a sweet-aholic who doesn't have diabetes, you may be at risk too. A review of eight studies in Japan assessed the levels of hemoglobin A1c, a marker for diabetes, and the rate of dementia within the general Japanese population. The authors found a concordance between an increased rate of elevated hemoglobin A1c and increased rates of dementia.

Increased memory impairments were even correlated with hemoglobin A1c levels greater than 6, which does not meet the threshold for diabetes. This may be related to increased production of insulin in people with higher intakes of sugar and carbohydrates, which subsequently leads to insulin resistance. Insulin resistance, in turn, may lead to a difficulty in the ability of neurons to transmit information to one another.

Of course, eating sweets also increases the likelihood of obesity, and midlife obesity itself has been correlated with dementia. There are many theories as to why this is the case, including that fat cells secrete brain-damaging inflammatory compounds or that fat cells store dangerous pesticides from the environment. What appears more likely is that obesity increases the risk of hypertension and sleep apnea, both of which increase the risk of dementia.

I understand that sweets bring pleasure and that telling people they shouldn't eat them seems cruel, but when you look at how much damage sweets create in both the body and mind, as a doctor, I find it difficult to condone their consumption. Consider that Native American populations have been ravaged by diabetes and poor health related to sweets, which were never traditionally part of their diet -- and this is a lesson all of us ignore at our peril.

Kicking this addiction will lead to improved physical and mental health and lower your risk for dementia. I know you can do it.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

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