Here, Dr Deborah Lee, Dr Fox Online Pharmacy, explores the link between diabetes and the increased risk of developing dementia.
In 2013, the journal Diabetes and Investigation published a large meta-analysis of 28 observational studies. The authors concluded that diabetes increased the risk of all types of dementia by 73%, Alzheimer’s Disease by 56%, and vascular dementia by 127%.
- Why should diabetes increase the risk of dementia?
- How does diabetes increase the risk?
- How can this risk be prevented?
Read on as I describe the key points about diabetes and dementia, then explain the biochemistry as simply as possible, and outline the steps you can take to reduce your risk of developing both these devastating medical conditions.
What is diabetes?
Diabetes is a long term medical condition in which your body can no longer control the level of blood glucose.
When things are working normally, your blood glucose levels rise after eating. This triggers the release of the hormone, insulin. Insulin facilitates the uptake of glucose inside your cells, where it is needed as energy for metabolic functions. As a result, your blood glucose levels fall back within the normal range.
When you develop diabetes, your blood glucose control mechanism is no longer working properly.
Increasing prevalence of diabetes
4.6 million people are currently living with diabetes in the UK, according to the charity Diabetes UK. Numbers of cases of diabetes have doubled in the past 20 years.
More than 1 million cases of diabetes in the UK remain undiagnosed. Many people remain completely unaware of their diagnosis. Early symptoms may be vague and go unrecognised.
A further 12.3 million UK residents are currently at increased of diabetes because they possess specific risk factors. Many of these risk factors are modifiable, such as obesity, smoking, alcohol, and taking exercise.
What is dementia?
Dementia is a chronic medical condition in which patients develop disordered thinking, difficulties reasoning, and memory problems. In due course, this causes interference with their daily activities. There are often speech and communication difficulties, troubles with problem-solving, and an overall deterioration in self-care. As dementia sets in, many people often undergo personality changes. They may also become very emotional. Eventually, most people with dementia cannot look after themselves and need 24-hour care.
Why does diabetes increase the risk of dementia?
Diabetes affects many of the complex physiologic and metabolic pathways in your body.
High blood sugars and high insulin levels cause brain inflammation which results in neurodegeneration.
There are 4 key processes/factors involved –
- Oxidative stress
- Insulin resistance (IR)
- Saturated fat
- Excess advanced glycation products (AEGs)
Causes of insulin resistance
IR develops with increasing age and is associated with obesity, smoking, lack of exercise, high blood pressure, and sleep disorders.
How to get diagnosed with insulin resistance
Diagnosing insulin resistance is not easy. You will need to take medical advice.
IR is more likely if your abdominal circumference measures over 32 inches for a female, or 40 inches for a male.
IR often occurs as part of metabolic syndrome.
Heath risks of insulin resistance
Insulin resistance is dangerous because it increases many health risks.
For example, IR doubles your risk of a heart attack or a stroke. It also trebles your risk that if these occur, they will be fatal. IR also increases your risk of many cancers.
Oncologists believe that obesity and insulin resistance play a role in the development of cancers such as breast and colon cancer.
Insulin resistance and dementia
Insulin resistance is one of the key underlying mechanisms causing dementia.
- IR disrupts cell-signalling – Brain function depends on cells signalling to each other using different chemical messengers. When IR is present, cell signalling is altered.
- Insulin degrading enzyme (IDE) – Insulin is broken down by an enzyme called insulin degrading enzyme (IDE). However, this enzyme also destroys amyloid-beta protein, which is deposited in Alzheimer’s Disease. When levels of insulin are high in the brain, IDE is in relatively short supply, with less availability to clear amyloid proteins.
Summary – the link between diabetes and dementia
In the UK, the increase in diabetes and dementia results from our Western lifestyle – notably, a diet high in saturated fat, and lack of exercise. These factors, amongst others, lead to the development of oxidative stress and insulin resistance. This is then further compounded for example, by the formation of toxic AEGs.
Living with high blood glucose levels, and high insulin levels, with insulin resistance, prediabetes, and diabetes, are major causes of neurodegeneration.