Alzheimer's Disease: Causes, Types, Symptoms, and Tests Used for Diagnosis

Alzheimer's disease is one of the most recognized and devastating neurological conditions, affecting millions of people around the world. Characterized by progressive memory loss, changes in thinking, and behavioral disturbances, Alzheimer’s deeply impacts not just those diagnosed but also their families and caregivers. While the exact cause remains partly understood, researchers know that Alzheimer’s disease involves the accumulation of abnormal proteins in and around brain cells, leading to brain shrinkage and cell death over time. Early diagnosis and intervention can’t stop the disease, but they can slow its progress and help patients and families plan for the future.

Alzheimer’s disease 

Alzheimer's disease is a progressive neurodegenerative disorder that leads to the death of brain cells and the loss of connections between them. It is the most common cause of dementia, a broad term for conditions characterized by memory decline and loss of other cognitive abilities severe enough to interfere with daily life. The disease usually starts subtly, with mild memory lapses or confusion, and gradually worsens over the years.
Eventually, Alzheimer’s can make it impossible for a person to carry out even basic activities like dressing, eating, or recognizing loved ones. Named after Dr. Alois Alzheimer, who first described the condition in 1906, Alzheimer’s disease is most common in older adults, though it can occasionally affect younger individuals.

Causes of Alzheimer’s disease

The precise causes of Alzheimer's disease are still being researched, but scientists believe it results from a combination of genetic, environmental, and lifestyle factors.
Here’s a closer look at these contributors:

1. Abnormal protein build-up:

• Beta-amyloid plaques: Sticky protein clumps that build up between neurons, disrupting communication.
• Tau tangles: Twisted fibers of another protein called tau that form inside neurons, leading to cell damage and death.

2. Genetic factors:

• The APOE ε4 gene variant increases the risk of late-onset Alzheimer’s, though having it doesn’t guarantee the disease.
• Rare mutations in genes like APP, PSEN1, and PSEN2 almost always cause early-onset familial Alzheimer’s.

3. Age:

• The most significant known risk factor; the risk doubles about every five years after age 65.

4. Cardiovascular health:

• Conditions like high blood pressure, diabetes, high cholesterol, and obesity are linked to higher risk.

5. Lifestyle and environment:

• Poor diet, lack of physical activity, smoking, and social isolation can also contribute.

6. Other factors:

• Severe head injuries, chronic inflammation, and reduced brain reserve due to lower education levels or fewer mentally stimulating activities.

Though not all causes can be controlled, adopting a healthy lifestyle may help reduce overall risk.

Types of Alzheimer’s disease

Alzheimer's disease can be divided into two primary types based on age of onset and genetic links:

1. Early-onset Alzheimer’s disease

• Occurs in people typically under age 65.
• Represents less than 5% of all Alzheimer’s cases.
• Often linked to inherited gene mutations.
• Symptoms can be more severe initially and may include unusual signs like problems with vision or language before memory loss.

2. Late-onset Alzheimer’s disease

• The most common form, typically affecting those aged 65 and older.
• Cause is more complex, involving a mix of genetic risk (like APOE ε4) and lifestyle or environmental factors.
• Symptoms generally begin with memory loss and gradually worsen over years.

Symptoms Alzheimer’s disease

Alzheimer’s disease affects each person differently, but most experience a range of cognitive, behavioral, and physical symptoms:

• Memory loss: Especially forgetting recently learned information, important dates, or repeatedly asking the same questions.
• Difficulty planning and solving problems: Trouble following familiar recipes, managing finances, or keeping track of appointments.
• Confusion about time or place: Getting lost in familiar surroundings or not knowing the day or year.
• Language problems: Struggling to find words, follow conversations, or complete sentences.
• Poor judgment and decision-making: Such as giving away large amounts of money or neglecting personal hygiene.
• Personality and mood changes: Increased anxiety, depression, irritability, or suspiciousness.
• Withdrawal: Avoiding work, social activities, or hobbies once enjoyed.
• Physical symptoms (in later stages): Trouble walking, swallowing, and eventually becoming bedridden.

These symptoms worsen gradually over years, with early signs often being subtle and easily mistaken for normal aging.

Tests Used for Diagnosis of Alzheimer’s disease

No single test can diagnose Alzheimer’s disease definitively during life, but a combination of medical history, cognitive tests, and imaging helps doctors make a reliable diagnosis.

1. Medical and neurological exams:

• Assess reflexes, balance, coordination, and sensory functions.

2. Cognitive and neuropsychological tests:

• Memory, problem-solving, language, attention, and reasoning are evaluated.

3. Brain imaging:

• MRI: Checks for brain shrinkage, strokes, tumors, or other abnormalities.
• CT scan: Similar to MRI, but often quicker; useful in emergencies.
• PET scans: Detect amyloid plaques or measure brain activity.

4. Laboratory tests:

• Blood tests rule out other causes of memory loss (like vitamin deficiencies or thyroid problems).

5. Cerebrospinal fluid (CSF) tests:

• Measure levels of beta-amyloid and tau proteins.

6. Genetic testing:

• Used selectively, especially if there’s a strong family history or symptoms appear at an unusually young age.

Diagnosis often involves a team, including neurologists, neuropsychologists, and geriatric specialists.

Conclusion

Alzheimer’s disease is more than just memory loss—it is a life-changing diagnosis that affects cognition, emotions, and daily living. While scientists continue to search for a cure, understanding its causes, recognizing early symptoms, and seeking timely testing can help patients and families manage the disease more effectively. Modern medicine offers treatments and strategies that may slow progression, ease symptoms, and support patients in maintaining independence as long as possible. Lifestyle choices like regular physical activity, balanced diet, mental stimulation, and strong social connections may also play a role in prevention.

Frequently Asked Questions (FAQ’s)

1. What is Alzheimer's disease?
Alzheimer’s disease is a progressive brain disorder that leads to memory loss and cognitive decline.

2. What causes Alzheimer's disease?
It’s caused by abnormal protein build-up in the brain, genetics, age, and lifestyle factors.

3. What are the early symptoms of Alzheimer’s disease?
Common early signs include memory loss, confusion, difficulty finding words, and mood changes.

4. Can Alzheimer's disease be cured?
Currently, there’s no cure, but treatments can slow progression and improve symptoms.

5. How is Alzheimer’s disease diagnosed?
Through cognitive tests, brain imaging, lab work, and sometimes genetic testing.

6. Who is at risk of developing Alzheimer’s disease?
Older adults, people with certain genetic factors, and those with unhealthy lifestyle habits.

7. What are the types of Alzheimer’s disease?
Early-onset (before 65, often genetic) and late-onset (after 65, most common).

8. Does Alzheimer’s disease always lead to severe memory loss?
Yes, it typically progresses to severe memory and functional decline over years.