What Causes Parkinson’s Disease, Alzheimer’s, and other forms of dementia?

The potential causes of Parkinson’s disease, Alzheimer’s, and other forms of dementia are complex and multifactorial. While each condition has its own unique pathology, they often share overlapping biological, environmental, genetic, and lifestyle-based risk factors that contribute to the degeneration of brain cells and cognitive decline.

Key Contributing Factors:

🧠 1. Genetic Susceptibility

While most cases of Parkinson’s and Alzheimer’s are not directly inherited, certain gene mutations increase susceptibility.
- Parkinson’s: Mutations in the LRRK2, PARK7, PINK1, and SNCA genes.
- Alzheimer’s: The APOE ε4 allele significantly increases risk.

These genes may affect how the brain handles proteins, inflammation, or oxidative stress.

2. Chronic Inflammation (Neuroinflammation)

Low-grade, long-term inflammation in the brain can damage neurons and promote plaques (in Alzheimer’s) or Lewy bodies (in Parkinson’s).
Microglial cells (the brain’s immune cells) become overactive, leading to self-destructive immune responses.

3. Oxidative Stress

The brain uses a lot of oxygen. This makes it vulnerable to oxidative damage from free radicals—unstable molecules that harm cells.

Inadequate levels of antioxidants like glutathione can leave neurons unprotected and accelerate their breakdown.

4. Mitochondrial Dysfunction

Mitochondria provide energy for neurons. When they malfunction, neurons can't maintain function or detoxify waste efficiently.

This leads to energy deficits, toxic buildup, and eventually cell death, particularly in areas like the substantia nigra (Parkinson’s) and hippocampus (Alzheimer’s).

5. Protein Misfolding & Aggregation

In Alzheimer’s, abnormal clumps of amyloid-beta plaques and tau tangles disrupt communication between brain cells.

In Parkinson’s, misfolded alpha-synuclein proteins form Lewy bodies, which disrupt dopamine production and neural communication.

6. Environmental Toxins

Exposure to pesticides, heavy metals (like mercury and lead), and industrial chemicals have been linked to higher risk of Parkinson’s and other neurological disorders.

Air pollution and toxins in food and water can contribute to long-term neurotoxicity.

7. Lifestyle & Metabolic Factors

Poor diet, sedentary lifestyle, and chronic stress increase risk by promoting inflammation, insulin resistance, and cardiovascular problems.
Diabetes, obesity, and high blood pressure are associated with vascular dementia and increase the risk of Alzheimer’s.

8. Impaired Cerebral Blood Flow

The brain requires constant, well-regulated blood flow.
Reduced circulation—due to aging arteries, heart disease, or stroke—can starve neurons of oxygen and nutrients, leading to cognitive decline.

9. Traumatic Brain Injury (TBI)

A history of concussions or head trauma has been linked to an increased risk of Alzheimer’s and Parkinson’s.

Brain injuries can initiate a cascade of inflammation, oxidative stress, and protein accumulation.

10. Sleep Deprivation

Poor sleep interferes with glymphatic clearance, the brain’s detox system.
Chronic sleep loss leads to buildup of toxic proteins, like amyloid-beta, and increases risk for neurodegeneration.

Other Factors

Gut health (the gut-brain axis): An imbalanced microbiome may increase neuroinflammation and toxicity.
Hormonal imbalances: Low estrogen, testosterone, or thyroid hormones can impact cognitive function.

Low neurotransmitter levels: Especially dopamine (Parkinson’s) and acetylcholine (Alzheimer’s).

What This Means for You

While there is no single cause, these factors interact and amplify one another over time. That’s why prevention and early intervention matter so much.

Focusing on brain-healthy lifestyle habits—including balanced nutrition (such as amino acids), physical activity, sleep, and stress management—can help lower your risk, support cognitive function, and improve quality of life at any age.