September 21 each year is International Alzheimer’s Day, a day established to remind and promote a shared global focus on a disease that seriously affects human health, especially the health of the elderly – Alzheimer’s disease. As a long-time Alzheimer’s clinician, I would like to discuss a question that many seniors have asked me: “Can I get Alzheimer’s disease?”
Alzheimer’s disease is the most common type of dementia, and the term – Alzheimerdisease (AD) – is becoming more widely known, with some studies suggesting that >40% of people over the age of 80 will develop AD.
So, what kind of people will get Alzheimer’s disease and what are the risk factors for getting Alzheimer’s disease (hereinafter called AD)?
I. Age
AD is a disease that affects older people, so the risk of developing AD increases with age, in other words, the longer you live, the more likely you are to get AD. the risk of developing AD is 5% in people older than 65 years old, and doubles with each additional 5 years of age, which means that the risk of developing AD reaches 10% by age 70, and 35% – 40% by age 85. –40%. But don’t worry about getting AD all day because of old age; studies have found that many people in their 80s have very good cognitive function. The onset of AD is related to many other factors besides age.
Second, family history
To illustrate this issue, I will first give a case in the United States. A gentleman, John, who was diagnosed with AD at the age of 41, was dismissed from his job because he could no longer do it well. By the time he was 37 to 38 years old he was already showing symptoms. John has a 42-year-old brother who also suffers from AD. Their mother died in her 60s and also had memory loss at that time. The medical center he visited found progerin after genetic testing, and a PET (single photon radio-positive electron scan) of the brain helped confirm that he had familial AD. It was very worrisome that this patient had three children, and experts recommended that they all undergo genetic testing, and that the patient himself had been placed in special care.
This example above reminds us that if we have a patient diagnosed with AD in our immediate family, that is, if we have a positive family history, we should be more concerned about our memory and should seek medical attention if there is a decline.
Third, women
Women are more likely to suffer from Alzheimer’s disease than men, and overall the ratio of women to men with the disease is 60:40. There may be two reasons for this, one is that men have a shorter life expectancy than women, making the number of elderly women more than men. The second reason is that estrogen has a protective effect on the brain, and after menopause women’s estrogen levels decline, thus this protective effect is affected.
IV. Indicators in the blood
There are some indicators in blood that can indicate the risk of AD, they are: homocysteine, thyroid function, blood sugar, Apo-E genotype, blood lipids, etc.
1.Blood homocysteine
Homocysteine can be measured in many hospitals (including ZJH), and this indicator will gradually increase with the lack of folic acid level, while hyperhomocysteinemia is closely related to the development of Alzheimer’s disease, vascular dementia, heart disease and stroke.
Previous studies have suggested an association between high homocysteine and ischemic stroke and heart disease. However, nearly 30 years of research in Framingham first suggested an association between homocysteine and the development of AD. More recently, a study from Italy found that both high homocysteine and folic acid deficiency doubled the risk of AD.
Why does high homocysteine increase the risk of AD? Because it promotes the production of free radicals and stimulates glutamatergic activity, and if blood homocysteine levels reach high levels, it can inhibit DNA repair and increase susceptibility to the toxic effects of amyloid, which is the main pathological basis of AD.
Homocysteine can be increased by genetic mutations, ageing, vitamin deficiencies, certain diseases, and poor lifestyle habits such as excessive alcohol, coffee, and smoking.
The normal homocysteine level is 4 – 12 mmol/L, with a moderate elevation in the range of 13 – 20 mmol/L, and more than 20 mmol/L is a serious excess.
2.Thyroid function
Hypothyroidism can also cause memory loss and dementia. In patients with hypothyroidism, thyroid stimulating hormone (FSH) in the blood rises and free T3 and T4 fall. Hypothyroidism can also manifest as depression, difficulty concentrating, chills, facial swelling, hoarseness, joint swelling, and muscle weakness.
In order to know how well the thyroid gland is functioning, thyroid function can be tested at any hospital. The normal range of thyroid stimulating hormone (FSH) is 0.4 – 4.0mIU/L, the normal range of T3 is 0.1 – 0.2mcg/dl, and the normal range of T4 is 4.5 – -11.2mcg/dl.
3.Glucose
Diabetes, especially type 2 diabetes, is an important risk factor for AD. This means that people with diabetes are more likely to get AD, but the onset of diabetes is relatively insidious. However, it is not difficult to detect diabetes, and it can be diagnosed by checking blood sugar, insulin level, glycated hemoglobin and glucose tolerance test. So you need to know the following data.
Normal fasting blood glucose is 70 – 100mg/dl, glycated hemoglobin is normally less than 5%, 5% – 7.0% is mildly elevated, 7% or more is significantly elevated. A glucose tolerance test is a test in which you drink twice as much water containing 75 grams of glucose after drawing fasting blood glucose, and then measure your blood glucose every hour for three hours. Glucose tolerance test can let us know the situation of blood sugar after meal.
4.Apo-E genotype
Apolipoprotein E (ApoE) is a class of protein that plays an important role in lipid metabolism, and ApoE has three main isoforms, E2, E3 and E4. Located on chromosome 19, three co-dominant alleles, ε2, ε3, and ε4, encode for the production of E2, E3, and E4, respectively, resulting in six protein phenotypes: three pure heterozygotes E2/2, E3/3, and E4/4, and three heterozygotes E2/3, E2/4, and E3/4. ApoE is associated with the development of Alzheimer’s disease (AD), and ApoE4 increases the risk of developing AD, according to According to a study by Dr. Green of the Boston University School of Medicine called REVEAl, the risk of AD is 0.8% if the protein phenotype is E2/E2, 3.2% for E2/E3, 5.1% for E3/E3, 18% for E3/E4, and up to 67% for individuals with the E4/E4 protein phenotype. The risk of AD in an elderly person older than 65 years of age with a blood test for the E4/E4 phenotype is 13 times higher than in the normal population.
Does having an ε4 gene mean that you will definitely develop AD? Many people with the disease causing gene do not develop the disease until they are old enough to develop it. Half of the people with AD do not have the gene.
We do not recommend routine testing for Apo-E genotype, but people with memory loss can have this gene tested. 50% of people with a clinical diagnosis of mild cognitive impairment who have the disease causing gene will turn into AD within 3 years, but these tests and consultations are best done in a specialized hospital, as sometimes inappropriate explanations can cause panic and be detrimental to the patient.
5. Blood lipid level
Studies have found that serum cholesterol is elevated during the transition to early dementia. It has long been known to doctors that cholesterol can cause cardiovascular disease, so testing lipid levels can also give us a clear idea of how to control them.
The normal ranges of blood lipids that we should know are as follows.
Total cholesterol level <199mg/dl, LDL cholesterol level <100mg/dl and triglycerides <150mg/dl.
There are many risk factors for AD, some of which can be changed, while others cannot be changed. Do you get AD? See if you have these risk factors.
1.Risk factors that cannot be intervened include age, family history, influence of genes, female.
2. Risk factors that can be intervened include hypertension, hyperlipidemia, heart disease, obesity, cerebrovascular disease, cranial trauma, vitamin deficiency, diabetes, and hyperhomocysteine.
In order to know the risk of having AD, we recommend the following blood tests to be performed at the hospital.
(1) Thyroid function
(2) Folic acid and vitamin levels
(3) Homocysteine
(4) Tests related to diabetes
(5) Lipid levels
(6) If there is a high suspicion of a genetic link, genetic testing is recommended
For these risk factors, there are many factors that can be intervened to prevent the occurrence and development of AD, except for the risk factors that cannot be intervened such as age and gender. If every elderly person can pay attention to their own risk factors for developing dementia and intervene effectively, it will help to reduce the overall prevalence of AD, which is also a blessing for every elderly person and even every family.