Alzheimer Disease - Everything You Need to Know

Medically reviewed by John A. Flores M.D., M.S. February 08, 2024| Written by Zenda Nel

Alzheimer Disease - Everything You Need to Know

Alzheimer disease (AD) and other dementias have become a major health concern with severe economic and caregiving burdens for societies and families. Unfortunately, this mental condition is increasing worldwide. According to the 2019 Global Burden of Disease (GBD) database, Alzheimer disease and other dementias increased147.95% from 2009 to 2019.

Ironically, the increase in Alzheimer disease over the last century is correlated with an improving healthcare system. Better health care results in many people living longer, which accounts for the increased elderly population. It's mostly the older people who are affected by AD and other neural disorders. 

According to Alzheimer Disease International, at least 55 million people across the globe currently have dementia. According to the World Health Organization (WHO), Dementiaresults from a variety of diseases and injuries that affect the brain. Alzheimer disease is the most common form of dementia and may contribute to 60–70% of cases.

The number of people with AD keeps growing with over 10 million new cases every year - roughly one new case every 3.2 seconds. 

The projections are that the number of AD patients will double every 20 years, reaching 78 million in 2030 and 139 million in 2050.

What is Alzheimer Disease?

Alzheimer disease is the most common form of dementia. It is aneurodegenerative condition that slowly and progressively destroys brain cells, affecting behavior and cognitive functioning. Eventually, the disease impacts all areas of life, including daily activities, and occupational functioning until even ordinary daily activities become problematic. There is currently no cure for this disorder.

Typically, AD first affects memory by destroying the neurons and their connections in parts of the brain that retain memory. Such a person may have problems recalling the names of people and places. In time, short-term memory is severely affected. 

Since AD is a progressive disease, the condition of the patient worsens over time. AD begins to affect the areas of the brain related to thought, language, reasoning, and social behavior. Such a patient grows more confused and disoriented, needing more and more supervision.

This stage is exceptionally hard for the family members who see their beloved struggling to speak, forgetting how to perform simple tasks, and disappearing into a world where they recognize no one. 

In due course, a person with Alzheimer succumbs to the disease and can no longer function independently. Currently, AD remains incurable as there's no proper treatment for it. 

What Causes It? – Current Research

The official medical pronouncement is that there is no apparent cause of AD and, therefore, no cure. AD mainly occurs in older people, but it's not a natural consequence of aging, and it's not expected that one typically dies of dementia.

Researchers have tackled the issue from several perspectives. Some suggest that AD is caused by a combination of factors related to aging, genetics, and environment. Lifestyle also plays a significant role. For example, consuming too much sugar for long periods increases blood sugar levels which has been found linked with an increased risk of Alzheimer disease. Meanwhile, people who remain mentally active show a reduced disease risk.

However, only a handful of these factors may be involved in any given case. It's because this disease is very unique to each person.

A Look at Some Answers That Might Be Emerging from Research 

Genetic Link

Studies show family history is the second major risk factor for AD, with aging being the first. Looking at twins and families, researchers have found that about 80% of all AD cases are related to people's genes. So far, changes in specific genes (like APP, PSEN1, and PSEN2) almost guarantee an early onset of AD (i.e., before 60). But that's rare; such patients account for only about 5% of AD cases. 

However, changes in common genes (such as the APOE gene) generally trigger AD much later in life. Mutations in the APOE gene account for about 30-50% of AD cases in families. Moreover, scientists have identified at least 11 more genes that may be involved in AD. 

A study involving the genetic data of more than 176,000 individuals has revealed that some people with a specific gene version, or allele, have a reduced risk of getting Parkinson's or Alzheimer. This protective allele is called DR4.

Oxidized Cholesterol Link

Experts suggest that oxidized cholesterol is 100 times more toxic than unoxidized cholesterol. Interestingly, there is increasing evidence that oxidized cholesterol may be behind the development of AD. Cholesterol gets oxidized when animal products are exposed to heat.Research suggests that oxysterols, which result from changes in cholesterol metabolism and high cholesterol levels, are involved in the development of this neurodegenerative disease.

An analysis of autopsy samples revealed that plaque deposits in the artery walls of AD victims contained 20 times more cholesterol than normal arteries. Meanwhile, the concentration of oxidized cholesterol was found to be about 45 times higher than normal levels. 

Examples of food rich in oxidized cholesterol include animal products, ghee, tuna, dairy, and eggs.

Sugar Link

Research evidence points toa link between type 2 diabetes and AD. In other words, people with Type 2 diabetes are at a greater risk of developing Alzheimer disease.

According toNeuroscience News, research at Wake Forest University School of Medicine has now revealed why this is so. The researchers found that a high sugar intake causes a rise in blood glucose levels, which can result in amyloid plaque build-up in the brain. Amyloid plaque is made up of toxic proteins, which increases the risk of Alzheimer disease. 

So, we can reduce the risk of amyloid plaque build-up and thus Alzheimer by simply cutting on sugar intake. One way to do this is to stop drinking sugary beverages. 

Onestudy that specifically explored the association of sugary beverages with dementia, AD, and stroke found that sugar in beverages increased the risk of Alzheimer. The researchers monitored 1,865 study participants over 16 years. They discovered that those individuals who consumed food higher in sugar content were at a higher risk of developing senile dementia, AD dementia, and stroke.

Early Signs of Alzheimer 

Having Alzheimer is different for every person. Many factors influence how the disease will present in each individual. Broadly speaking, the most common early sign of Alzheimer and other forms of dementia is a loss of memory.

However, don't panic if you find that you are forgetful – we all struggle with memory as we get older. Let's look at the matter in more detail because it's important to know as the incidence of AD is becoming pretty common.

Memory loss

Someone who is developing AD doesn't just forget someone's name like we often do. Instead, they can’t remember what they did a few moments ago. After all, it's the short-term memory that gets affected first. This may have dire consequences, for instance, when someone doesn't remember that they have already taken their medication. 

Short-term memory loss is a commonplace early symptom of dementia. 

Reduced Cognitive Abilities

  • Daily routine tasks, like dressing or showering, may seem too complicated.
  • Inability to concentrate, plan, and make decisions for even ordinary tasks (e.g., cannot decide what to wear).
  • Struggle to keep up with a conversation, a TV program, or an article.

Getting Disorientated

Someone who has dementia can become lost in familiar surroundings and forget how they got there or how to return. This makes it very challenging to care for people with AD. 

Misplacing Things

Helping someone with AD find something they misplaced is like going on a scavenger hunt – the object can be literally anywhere, as AD victims tend to put things in all kinds of illogical places. 

Visual and Spatial Issues

People with dementia don't see things as they appear to others – they don't see contrasts, especially if the colors are too similar. For instance, if a white wall has a closed door that is also white, the person may perceive the door as a part of the wall. 

Seeming Personality Changes 

Someone with AD may become very confused and unhappy and start behaving in uncharacteristic ways. Some become erratic in their behavior, while others become withdrawn, showing no interest in anyone or anything.

Factors That Increase Someone's Risk of Alzheimer

Asystematic review and meta-analysis of 396 studies has turned up eight risk factors for Alzheimer. 


With diabetes, the sugar level in the blood is too high. This can damage organs in the body, including the brain. Research studies are finding a strong correlation between type 2 diabetes and Alzheimer disease. For instance, people with high blood sugar levels have been discovered to have high levels of beta-amyloid protein - a brain protein related to Alzheimer disease.

Orthostatic hypotension 

Orthostatic hypotension is a type of low blood pressure that is common in patients with AD. Some people with low blood pressure experience dizzy spells when they get up from a sitting position. This happens when the brain doesn't receive enough blood supply because of the low pressure. Over time, this lack of blood supply can harm the brain cells due to a lack of oxygen.

Hypertension in Midlife

The link between blood pressure and Alzheimer is well established. In 2013, astudy at Johns Hopkins confirmed that older people with high blood pressure, or hypertension, were more likely to have biomarkers of Alzheimer in their spinal fluid. 

Hypertension can lead to Alzheimer because the pressure can damage small blood vessels in the brain responsible for thinking and memory.

Head Trauma

A major head trauma can increase the risk of Alzheimer, especially later in life. However, theAlzheimer Association suggests that a single mild incident doesn't necessarily lead to AD. Rather, it's experiencing several mild brain injuries that may present a greater risk of developing AD. For instance, participants in sports like American football, boxing, hockey, and soccer who repeatedly suffer head injuries may experience cognitive decline and eventually dementia.


Stress affects many health conditions, leading to a suppressed immune system. Stress may also play the same role in the onset of AD. Recent studies suggest that stress may be involved in accelerating the onset of Alzheimer disease as well as worsening the disease course.

Even so, there's currently no definite proof that stress alone can trigger AD.


The review found a link between depression and an increased risk of Alzheimer disease. However, researchers haven't determined yet if depression is the result of the disease or the cause of it. Either way, they speculate that depression harms the brain, increasing its susceptibility to conditions like Alzheimer and other types of dementia.

Scientists remind us not to fear Alzheimer just because we feel depressed. Feeling depressed doesn't mean you'll get dementia; it only increases your risk of acquiring it.

Midlife Obesity 

Another factor that was highlighted by the study is that obesity in midlife may increase the risk of dementia and AD later in life. It was established that body mass index (BMI) is a risk factor for AD, but exactly how it comes about is unclear.

Astudy that looked at data from about 1.3 million adults found an increased risk for AD among the obese. Still, weight loss before the onset of dementia seemed to show no increase in dementia among the obese. So, a high BMI before age 65 that continues over an extended period appears to increase a person's risk.

Heart Surgery

Clinicians have observed cognitive decline that happens after cardiac surgery. More than one study confirms this observation. A landmarkstudy that was reaffirmed through similar studies showed that about 40% of all heart patients were cognitively impaired five years after heart surgery. 

The Effects of Plant-Based Diet on Alzheimer Disease

The first thing to understand is the relationship between atherosclerosis and the risk of developing AD. Atherosclerosis is associated with heart attack, stroke, and other disorders that affect the blood supply. But this condition evolves when cholesterol, fat, blood cells, and other substances form 'plaque' in the blood. 

Gradually, this sticky stuff or plaque starts clinging to the walls of the arteries, causing them to constrict. The result is a reduced flow of nutrient-carrying blood to the organs and tissues in the body, including the brain.

The brain is dependent on a constant flow of blood for optimal functioning. A systematic review found that reduced blood flow to the braindue to atherosclerosis may be a factor in cognitive decline and may increase the risk of Alzheimer disease.

Researchers point out though, that the mechanisms linking atherosclerosis and Alzheimer are complex and still not fully understood.

So, the best diet for someone with Alzheimer is that it doesn't cause plaque build-up in the brain arteries. Otherwise, this can limit the amount of oxygenated blood the brain receives. And it's this diminishing amount of oxygen and nutrients that damages the brain over time.

The MIND Diet

Dr. Martha Clare Morris and her colleagues at Rush developed the Mediterranean-DASH Intervention for Neurodegenerative Delay(MIND) diet was developed by  The diet is a combination of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets. These diets have been shown to reduce the risk of cardiovascular conditions like hypertension, heart attack, and stroke. 

The MIND diet requires individuals to have at least three servings of whole grains, a salad, and one other vegetable every day, and a glass of wine. In addition, beans are eaten three to four times a week, poultry and berries at least twice a week, fish once a week, and nuts every second day.

The team conducted a study on the MIND diet and found that participants who adhered to it reduced their risk of AD by as much as 53%. Individuals who followed it reasonably well reduced their risk by 35%. 

The MIND diet divides food into two groups: foods healthy for the brain and food to avoid.

Healthy Brain Food

  • All vegetables, including green leafy ones
  • Whole grains like unpolished rice, barley, and millet
  • Beans
  • Fish
  • Poultry
  • Nuts
  • Berries
  • Olive oil
  • Wine 

Unhealthy Brain Food  

  • Red meats
  • Butter and stick margarine
  • Cheese
  • Pastries and sweets
  • Fried or fast food

Further research also supports a plant-based diet to prevent or minimize cognitive impairment as we age. 

In a study, French scientists monitored 800 people aged 65 or more for twelve years. They found that eating more fruits, vegetables, and other plant-based foods can help reduce the risk of cognitive decline. The study was published in Molecular Nutrition and Food Research. The scientists found cocoa, coffee, mushrooms, apples, and blueberries protect the brain against decline.

The Effects of Lifestyle Changes on the Disease

Alzheimer disease is not curable, but we can take action to minimize the chances of developing the disease later in life. Since studies have found an association between a healthy lifestyle and a lower risk of AD, it's critical to know about these lifestyle habits and to consider adopting them. 

The National Institutes of Health (NIH)reports research has identified five lifestyle habits that, in combination, can substantially lower the risk for Alzheimer disease. 

The observational study looked at data from about 3,000 research participants. They wanted to see whether participants followed five specific healthy habits and how this behavior affected their chances of getting AD.

What they found is good news – participants who exhibited four or all of the five specified healthy habits had a 60% lower risk of Alzheimer. 

The Five Behaviors That Substantially Reduce Your Risk of AD

 The researchers highlighted the following behaviors: 

  • Physical exercise – at least 150 minutes of moderate to vigorous physical activity per week.
  • Following the MIND diet – that is a diet that prioritizes plant-based foods.
  • Not smoking. Scientists know that smoking shrinks the brain. 
  • Light to moderate use of alcohol.
  • Continued cognitive engagement – keeping the mind active.

While the results are encouraging, there isno definitive evidence that we can prevent Alzheimer disease. Nonetheless, a lifestyle that includes a healthy diet, physical activity, and mental stimulus while it excludes extreme alcohol use and smoking can lower the risk of AD and other age-related chronic diseases.

Final Thoughts

Despite billions of dollars spent on research, there is still no cure or effective treatment for Alzheimer disease. But we are not entirely helpless in the situation. We can choose healthier lifestyle habits and reduce our risk of developing AD later in life. 

Diets rich in saturated fat and cholesterol compromise our arteries and blood vessels, leading to the brain being starved of nutrients and oxygen. So, scientists suggest people follow a plant-based diet rich in fruits, vegetables, and whole grains to reduce dementia risk. 

Now, it's up to us to keep ourselves well informed of the consequences and take action in the best interest of our health.