Is Alzheimer's Disease Contagious? What Do the New Findings Say?

The question of "Is Alzheimer's disease contagious?" has been a topic of interest for many years. A new study published in February 2024 in the journal Nature Medicine offers a different perspective on this question. According to the research, individuals who received growth hormone injections derived from cadavers in the past showed signs of developing Alzheimer's disease at an early age.

This suggests that Alzheimer's may not be solely explained by genetic factors. It also raises the potential risk of certain medical practices.

What Is Alzheimer's Disease?

Alzheimer's disease is a progressive neurological disorder that starts with the accumulation of proteins in the brain. It is typically characterized by memory loss, cognitive decline, and changes in behavior. It is the most common type of dementia. The incidence increases with age but can also occur in younger individuals.

How Does Alzheimer's Develop in the Brain?

In Alzheimer's disease, structural and biochemical changes progress in the brain over time. The most significant changes include the formation of beta-amyloid plaques, which disrupt communication between neurons, and the accumulation of tau protein tangles within cells. These accumulations impair the function of brain cells and eventually lead to cell death.

These changes usually begin in the hippocampus, the region responsible for memory and learning. As the disease progresses, other areas such as the frontal, parietal, and temporal lobes are affected. Consequently, individuals experience impairments in thinking, decision-making, language, and motor functions.

What Is the Difference Between Alzheimer's and Dementia?

Dementia refers to the general loss of mental faculties, while Alzheimer's is the most common cause of dementia. All individuals with Alzheimer's experience dementia, but not all dementia cases are due to Alzheimer's.

What Are the Symptoms of Alzheimer's?

Alzheimer's disease typically has a subtle onset. Symptoms progress over time and increasingly affect an individual's daily life. Early detection of symptoms is crucial for an accurate diagnosis and treatment process.

Early Symptoms of Alzheimer's

• Forgetfulness: Particularly forgetting recent information (e.g., appointments, names, conversations).
• Confusion about time and place: Getting lost in familiar places or mixing up dates.
• Difficulty making decisions: Hesitating when making everyday choices, leading to incorrect decisions.
• Trouble finding words: Struggling to find the right word while speaking or frequently leaving sentences incomplete.
• Misplacing everyday items: Confusion about the locations of items like keys and wallets.

Advanced Symptoms of Alzheimer's

• Serious difficulty communicating: Struggling to understand and form even simple sentences.
• Impairments in basic functions: Difficulties with eating, dressing, and other essential activities.
• Changes in personality and behavior: Displays of aggression, suspicion, social withdrawal, and depression.
• Problems with walking, balance, and coordination.
• Difficulty swallowing and significant weight loss.

As Alzheimer's progresses, the patient may become entirely dependent on others. Therefore, early awareness and support are of utmost importance.

Is There a Treatment for Alzheimer's?

Unfortunately, there is currently no definitive treatment that can halt or reverse Alzheimer's disease. However, certain medications and supportive therapies can slow the progression of symptoms and enhance quality of life.

Medication Treatments

• Cholinergic drugs (donepezil, rivastigmine, galantamine): These medications increase acetylcholine levels in the brain, contributing to memory and attention processes.
• NMDA receptor antagonist (memantine): Can reduce cell death by balancing glutamate levels.
• In recent years, anti-amyloid antibody treatments (e.g., lecanemab) that have received FDA approval aim to target beta-amyloid plaques and interfere with the underlying mechanisms of the disease. These medications are still under research and may not be suitable for every patient.

Supportive Approaches

• Cognitive therapy: Memory exercises to support cognitive function.
• Physical activity: One of the key factors supporting brain health.
• Nutrition: Diets with anti-inflammatory effects, such as the Mediterranean diet, are recommended.
• Social support and family counseling: Education for caregivers, emotional support, and psychological resilience are crucial.

What Are the Types of Alzheimer's?

Alzheimer's disease presents with different subtypes. Familial Alzheimer's is a rare form associated with genetic mutations and early onset. In contrast, late-onset Alzheimer's is more common and may be linked to the APOE4 gene allele.

Familial Alzheimer’s

Less than 1% of total Alzheimer’s cases are defined as familial Alzheimer's (hereditary form). This type typically:

• Begins at an early age (usually between 30-60 years).
• Occurs in individuals with mutations in the APP, PSEN1, and PSEN2 genes.
• Features a family history of early-onset Alzheimer's in multiple individuals.

Such cases can be identified through genetic testing, and research is being conducted on preventive strategies for carriers.

Late-Onset Alzheimer's and APOE4

In late-onset Alzheimer's disease, the APOE (Apolipoprotein E) gene, particularly the ε4 allele, is identified as a risk factor. However:

• Not every individual carrying APOE4 will develop Alzheimer's.
• Not every individual with Alzheimer's carries APOE4.

Thus, this gene only increases risk and is not a direct cause. Additionally, factors such as lifestyle, diet, exercise, and mental activities can mitigate the effects of this genetic risk.

Is Alzheimer's Disease Contagious?

Alzheimer's disease is not typically confused with infectious diseases. However, some recent studies have raised questions about the potential for transmission in rare cases. Nevertheless, there is no scientific evidence suggesting that Alzheimer's can be passed from person to person in daily life. Consequently, the disease is not considered contagious in the classic sense.

The Connection Between Alzheimer's and Prion Diseases

Prion diseases arise from the misfolding of proteins in the brain and are infectious. A similar mechanism may play a role in Alzheimer's disease:

• Brain cells can be damaged due to the misfolding of proteins known as beta-amyloid.
• Researchers suggest that these proteins could potentially be transmitted through cadaver-derived hormones to other individuals.

This similarity increases the possibility that Alzheimer's may be transmissible under certain conditions. However, there remains no clear information regarding the likelihood of transmission through social contact.

Claims of Transmission Through Growth Hormone

A study conducted in 2015 found beta-amyloid accumulations in the brains of some individuals who had received brain-derived growth hormone (cadaveric hGH). This finding raised the claim that certain medical interventions might share similar pathological changes to Alzheimer's.

However, this applies only to very specific medical scenarios and poses no risk in daily life. Currently, such growth hormone applications are no longer used. Therefore, this research points to a past application that was outside clinical and ethical standards.

What Were the Findings of the Study?

In the study published in Nature Medicine:

• Participants were individuals who received growth hormone injections derived from cadavers during childhood or adolescence.
• Early-onset Alzheimer's developed in individuals aged 38 to 55.
• None of them had mutations predisposing them to Alzheimer's.

These findings suggest that the disease can develop due to not only hereditary factors but also environmental or medical interventions.

Note: After 1985, the use of cadaver-derived growth hormones was banned. Synthetic hormones used today do not carry this risk.

What Do New Research Studies Say About Alzheimer's?

Scientists are conducting intensive research to understand the causes and treatment pathways of Alzheimer's disease. Recent studies indicate that lifestyle and environmental factors, in addition to genetic predispositions, significantly impact the development of the disease.

The new findings particularly focus on developing biomarkers that could enable early diagnosis and prevention of the disease.

What Are Other Risk Factors Leading to Alzheimer's?

Alzheimer's disease is associated with many different factors beyond the potential for contagion:

• Advanced age
• Genetic predisposition (such as the APOE-e4 gene)
• Unhealthy diet and sedentary lifestyle
• Chronic diseases like diabetes and hypertension
• Low educational levels and lack of mental stimulation

Some of these factors are preventable risks. Lifestyle changes can significantly reduce this risk.

Is It Possible to Prevent Alzheimer's?

While there is no guaranteed way to completely prevent Alzheimer's disease, scientific research has shown that certain lifestyle changes can reduce the risk. Specifically, the following factors are highly effective for healthy brain aging:

Prevention Strategies

• Maintain mental activity: Activities such as learning new things, reading, solving puzzles, and studying a foreign language can enhance brain reserve.
• Prioritize physical activity: It’s recommended to engage in at least 150 minutes of moderate exercise per week, such as walking, swimming, or dancing.
• Eat a balanced, brain-friendly diet: The Mediterranean diet, omega-3 fatty acids, antioxidants, and low-sugar diets are preferred.
• Stay socially engaged: Maintaining communication with family and friends and participating in social environments prevent isolation.
• Manage chronic diseases: Conditions like hypertension, diabetes, obesity, and high cholesterol can directly affect brain health.
• Ensure quality sleep: The brain detoxifies during sleep. Sleep disorders can increase the risk of Alzheimer's.

Living With Alzheimer's: Recommendations for Patients and Their Families

Receiving an Alzheimer's diagnosis is a challenging process for both patients and their families. However, with appropriate care, patience, and information, this process can be made more manageable.

Suggestions to Improve the Quality of Life for Patients

• Establish a routine: Organizing daily activities in a specific order helps the patient feel secure.
• Reduce environmental stimuli: Loud, crowded, and complex environments can increase confusion.
• Communicate simply and clearly: Using slow, clear, and short sentences can be effective.
• Implement safety measures: Home adjustments should be made to prevent dangers such as falling risks or leaving the stove on.

Support for Family Members and Caregivers

• Seek emotional support: Caregivers of Alzheimer's patients may experience emotional issues such as depression and burnout. Psychological support is important.
• Educate yourself about caregiving: Understanding the stages of the disease and expected developments can facilitate the process.
• Do not neglect your own health: Taking care of your own physical health and ensuring rest and socialization are equally essential.
• Join support groups: Connecting with others who share similar experiences can reduce feelings of loneliness.