Alzheimer’s Disease – Symptoms and Causes

Overview

Alzheimer’s disease is the leading cause of dementia worldwide. This condition starts when proteins create amyloid plaques and neurofibrillary tangles in the brain, leading to the death of brain cells and brain shrinkage.

In the United States, approximately 6.9 million people aged 65 and older have Alzheimer’s disease. About 70% of these individuals are 75 or older. Globally, Alzheimer’s accounts for 60–70% of the estimated 55 million dementia cases.

Early warning signs typically include difficulty remembering recent events or conversations. As the disease progresses, memory problems worsen, and daily activities become increasingly challenging.

Key facts about Alzheimer’s:

• No cure currently exists
• In later stages, complications like dehydration, malnutrition, or infection can be fatal
• Medications may help manage symptoms or slow cognitive decline
• Support services are available for patients and caregivers

The disease follows a progressive pattern, with symptoms gradually becoming more severe over time. Brain function deteriorates, affecting not just memory but also judgment, language skills, and the ability to perform familiar tasks.

Signs and Symptoms

Memory Changes

Memory problems are the main sign of Alzheimer’s disease. Unlike normal forgetfulness, these memory issues persist and worsen over time.

People with this condition might:

• Ask the same questions repeatedly
• Forget about recent conversations or events
• Put items in unusual places
• Become disoriented in familiar surroundings
• Struggle to remember names of family members or common objects
• Have trouble finding words during conversations

These memory difficulties eventually make daily life and work much harder.

Thinking Problems

As the disease progresses, focus becomes difficult, especially when thinking about abstract ideas like numbers. People might:

• Struggle to complete multiple tasks at once
• Have trouble managing money or paying bills on time
• Eventually fail to recognize numbers
• Find complex thinking increasingly challenging

Decision-Making Difficulties

Poor judgment becomes common with Alzheimer’s disease. A person might:

• Make inappropriate social choices
• Dress improperly for weather conditions
• Struggle with everyday problems
• Not know how to respond to situations like food burning on the stove
• Have trouble making safe driving decisions

Trouble with Familiar Tasks

Engaging in activities that require a sequential order of steps can be quite challenging. Someone with Alzheimer’s might:

• Find it hard to plan and prepare meals
• Struggle with once-familiar games
• Eventually forget how to do basic self-care, like dressing and bathing

Personality and Behavior Shifts

Brain changes can significantly affect mood and behavior, causing symptoms like:

• Depression and loss of interest in activities
• Withdrawal from social situations
• Mood swings and irritability
• Suspicion of others
• Anger or aggressive behavior
• Changes in sleep patterns
• Wandering behavior
• Reduced inhibitions
• False beliefs, like thinking items were stolen

Remaining Abilities

Even as the disease progresses, some skills often remain intact longer. These preserved abilities may include:

1. Reading or listening to books
2. Telling stories and sharing memories
3. Singing or enjoying music
4. Dancing
5. Drawing or crafting

These skills typically last longer because they use brain areas unaffected in later disease stages.

When to Consult a Doctor

If you notice memory problems or thinking difficulties in yourself, talk with a healthcare provider. Several conditions can cause memory issues, and some are treatable.

If you’re worried about changes in a family member or friend, suggest accompanying them to a medical appointment. Early evaluation can lead to better management of symptoms and planning for the future.

Causes

Alzheimer’s disease develops when brain proteins begin to malfunction. This triggers a chain reaction that damages neurons, breaks connections between them, and eventually leads to cell death.

Most cases result from multiple factors working together over time. These include genetic, lifestyle, and environmental elements that gradually harm brain tissue.

In fewer than 1% of cases, certain genetic mutations almost ensure the disease will develop, typically beginning in middle age.

The damage process begins years before any symptoms appear. It typically starts in memory centers before spreading to other brain regions in a predictable pattern. By late stages, significant brain shrinkage has occurred.

Two key proteins play central roles in Alzheimer’s:

• Beta-amyloid fragments: These clump together, disrupting communication between brain cells. The clumps eventually form larger deposits called amyloid plaques.

• Tau proteins: Normally, these help transport nutrients throughout brain cells. In Alzheimer’s, tau proteins change shape and organize into structures called neurofibrillary tangles, which damage the cell’s transport system.

Investigations are ongoing into the origins and transmission of these protein abnormalities. Scientists believe understanding these mechanisms will be crucial for developing effective treatments to slow or stop disease progression.

Brain imaging can reveal these changes, showing plaque buildup and areas of brain tissue loss. These changes typically progress from mild to severe as the disease advances through its stages.

Risk Factors

Getting Older

Age is the strongest risk factor for Alzheimer’s disease. While not a normal part of aging, your chances increase significantly as you get older.

Research shows the impact of aging clearly: for every 1,000 people aged 65–74, about 4 new cases are diagnosed each year. This jumps to 32 new cases for ages 75–84, and 76 new cases for those 85 and older.

Family Links and Genes

Having a parent or sibling with Alzheimer’s raises your risk. While most genetic factors are complex, scientists have identified specific genes that play a role.

The APOE e4 gene version is present in 25–30% of people and increases Alzheimer’s risk. Having two copies of this gene raises the risk even more than having just one copy.

Scientists have found rare genetic changes that almost ensure Alzheimer’s development, but they represent less than 1% of all cases.

Down Syndrome Connection

People with Down syndrome often develop Alzheimer’s disease earlier than others, typically 10–20 years sooner.

This likely occurs because they have three copies of chromosome 21, leading to the production of proteins that create beta-amyloid, the substance that forms brain plaques.

Gender Differences

More women develop Alzheimer’s disease than men. This difference primarily exists because women generally live longer than men, giving the disease more time to develop.

Mild Cognitive Impairment

People with mild cognitive impairment (MCI) have memory or thinking issues that are worse than normal aging, but they can still manage daily activities.

Having MCI significantly increases the risk of developing dementia later. When memory is the main problem, progression to Alzheimer’s is more likely.

An MCI diagnosis allows people to:

• Make healthy lifestyle changes
• Develop memory compensation strategies
• Set up regular checkups to monitor symptoms

Brain Injuries

Research indicates that individuals over 50 with traumatic brain injuries (TBI) have an increased risk of dementia and Alzheimer’s disease. This risk increases further with severe injuries or multiple TBIs over time.

Air Quality Issues

Animal studies reveal that air pollution particles can damage the nervous system. Human research links exposure to pollutants—especially from traffic exhaust and wood burning—to increased dementia risk.

Heavy Drinking

Excessive alcohol consumption causes known brain changes. Multiple large studies have found links between alcohol misuse and a higher risk of dementia, particularly early-onset dementia.

Sleep Problems

Poor sleep patterns, like difficulty falling or staying asleep, are connected to increased Alzheimer’s risk. Sleep apnea may also raise dementia risk.

Heart Health Connections

The same factors that harm your heart may increase dementia risk:

• Limited physical activity
• Excess weight
• Smoking (including secondhand exposure)
• High blood pressure
• Elevated cholesterol
• Poorly controlled type 2 diabetes

Elevated LDL cholesterol levels during middle age significantly increase the risk of developing dementia. Research shows people under 65 with high LDL levels face a greater risk, though cholesterol-lowering medications don’t increase risk.

Hearing Difficulties

Research shows hearing loss increases dementia risk—the more severe the hearing loss, the higher the risk. However, using hearing aids appears to protect against dementia development.

Untreated Vision Problems

Newer studies suggest untreated vision problems may increase cognitive impairment and dementia risk.

This connection might stem from conditions like diabetes that affect both vision and brain health, but vision loss itself may independently raise dementia risk.

Mental Stimulation and Social Life

Staying socially active and mentally engaged throughout life can lower Alzheimer’s risk. Lower education levels—particularly less than high school completion—appear to be a risk factor for developing the disease.

Health Problems Linked to Alzheimer’s Disease

As Alzheimer’s disease progresses, it creates several health challenges beyond memory issues. Brain changes make it difficult for patients to manage their overall health in important ways.

People with Alzheimer’s often struggle to:

• Report pain or discomfort
• Describe symptoms of other illnesses
• Follow medical instructions correctly
• Recognize medication side effects

In advanced stages, physical functions become affected as brain changes worsen. This leads to several serious complications:

Physical Problem	Possible Complications
Swallowing difficulties	Food or liquid entering lungs
Balance problems	Falls and broken bones
Weakened immune system	Infections, pneumonia
Limited mobility	Pressure sores (bedsores)
Poor eating/drinking	Malnutrition and dehydration
Bowel/bladder control issues	Constipation or diarrhea

Each physical problem increases the risk of additional health issues, creating a challenging cycle for patients and their care teams.

Prevention

While Alzheimer’s disease cannot be completely prevented, research shows that certain lifestyle changes may reduce your risk. Many of these changes focus on heart health, which is linked to brain health.

Regular physical exercise helps both your heart and brain. Try to be active most days of the week. Even moderate activity like walking can make a difference.

A Mediterranean diet has been shown to slow cognitive decline as people age. This eating pattern includes:

• Plenty of fruits and vegetables
• Whole grains
• Fish and poultry
• Nuts and olive oil
• Limit red meat and processed foods

Taking care of health conditions is crucial. Work with your healthcare provider to manage:

• High blood pressure
• Diabetes
• High cholesterol (especially LDL cholesterol)

If you smoke, quitting is one of the best things you can do for your brain health. Ask your doctor for resources to help you stop.

Getting proper glasses or hearing aids can help protect your cognitive function.

Activities that challenge your mind and connect you with others may lower your risk of Alzheimer’s disease. Consider:

1. Reading books or magazines
2. Playing board games or cards
3. Taking classes to learn new skills
4. Attending social events
5. Playing musical instruments
6. Creating art or crafts

These approaches work best when combined. Small changes in several areas of your life may have a greater impact than focusing on just one factor.