Young Ju, Ph.D.

Alzheimer’s disease is the most common type (60-80%) of dementia. It is an irreversible and progressive neurodegenerative brain disorder characterized by memory loss that affects one’s ability to carry out everyday activities.

Alzheimer’s Disease Facts (1-3)

According to the Center for Disease Control and Prevention, approximately 6.7 million Americans age 65 and older are living with this disease in 2023.  This number is projected to increase to 14 million by 2060. It’s the 6th leading cause of death among US adults and the 5th leading cause of death among adults age 65 and older.

Changes in the Brain (1, 2)

Brain cells are composed of neurons and non-neuronal cells (also called glial cells) (Figure 1). The healthy human brain contains tens of billions of neurons. Within the neuron, when a signal is received by the dendrite, the signal is passed on to the axon. When the signal reaches the end of the neuron, neurotransmitters (signaling molecules) are released to the synaptic space (the space between neurons) and the signal is transmitted to other neurons. There are also non-neuronal cells (e.g., astrocytes and microglia) that support synapse development and respond to neuronal signals.

Amyloid plaques (abnormal breakdown of a protein called the amyloid precursor) between neurons and neurofibrillary tangles (abnormal accumulation of a protein called tau) inside neurons are formed in brains with Alzheimer's (Figure 2).

Several changes in the brain are associated with the progression of Alzheimer’s disease:

• Accumulation of amyloid plaques and tau tangles.

• Increased oxidative stress and oxidative damage–an imbalance between the production and elimination of free radicals (chemically reactive and unstable atoms) that can damage brain cells.

• Increased neuroinflammation–the activation of the immune system in response to inflammatory triggers in the brain. An imbalance between inflammation and anti-inflammation could cause brain cell damage and dysfunction.

•  Reduced synapses and neuron-to-neuron communication at synapses

• Increased brain cell death

Risk Factors (1-3)

It is likely that multiple factors contribute to the development of Alzheimer’s disease:

• Age:   Age is the biggest known risk factor and the risk for Alzheimer’s increases as we get older. 

• Gender:  Twice as many women have Alzheimer’s.

• Family History:  People with a family history and who have first-degree relatives (e.g., a parent or sibling) diagnosed with Alzheimer’s are at a higher risk.

• Lifestyle: Physical inactivity, unhealthy diet, alcohol consumption, smoking, sleep problems, and social isolation, etc., are associated factors.

• Medical Conditions:  Research studies have shown strong associations between medical conditions such as high blood pressure, high LDL-cholesterol (bad cholesterol), diabetes, overweight/obesity, hearing loss, depression, mild cognitive impairment, head injury (e.g., concussion, traumatic brain injury), and Down Syndrome.

• Genetics: People who carry the apolipoprotein E (APOE e4) gene have a higher risk–about 40-60% of Alzheimer’s patients are APOE e4 carriers.

Stages and Symptoms (1, 2)

Alzheimer’s disease is categorized into three stages: mild, moderate and severe. A seven-stage categorization is also used. Although the rate of the disease progression and the symptoms vary, the symptoms worsen over time. 

• Mild, early stage: mild forgetfulness, problems remembering names, recalling recent events, making plans, managing money

• Moderate, middle stage: increasing trouble remembering things, problems learning new things, making plans, problems with reading, writing, and working with numbers

• Severe, late stage: losing many physical abilities, losing bowel and bladder control, problems having a conversation, needing help with all daily activities; weakened immune function and frequent infections, unaware of surroundings

Diagnosis (1, 2)

The early signs of Alzheimer’s disease may not be noticeable. To make a diagnosis, healthcare professionals do an interview using several types of tests to check various cognitive functions and asking questions about past and current health conditions to check the status and possible causes of memory loss or confusion. Brain image scans, such as CT (computed tomography), MRI (magnetic resonance imaging), or PET (positron emission tomography) may also be included to check changes in brain structure. 

Treatments (1, 2)

Currently, there is no cure for Alzheimer’s disease. Several prescription drugs approved by the U.S. FDA (Food and Drug Administration) are available to delay the disease progression. The therapeutic response rate of these drugs widely varies (20-60%).

• Medications for mild to moderate stage: 

•  Inhibit the breakdown of acetylcholine (a neurotransmitter) to improve memory and thinking.

• Reduce amyloid plaque

• Medications for moderate to severe state

•  Reduce excessive amounts of glutamate (a neurotransmitter) to prevent brain cell death by reducing toxicity.

• Other optional medications to aid other conditions

•  Antipsychotic drugs for hallucinations, delusions, paranoia, agitation, aggression

•  Anti-anxiety drugs for agitation

•  Sleep aids

•  Anticonvulsants for aggression

What You Can Do to Reduce Risk of Alzheimer’s Disease (1-3, 6)

Although there is yet no way to prevent Alzheimer’s disease, check off the following healthy lifestyle choices to reduce your risk of the disease. 

• Manage high blood pressure and high blood sugar.

• Maintain a healthy weight.

• Be physically active.

• Quit smoking.

• Avoid alcohol consumption.

• Treat hearing loss–hearing aids could reduce the rate of cognitive decline.

• Get enough sleep.

• Get routinely administered vaccines, including diphtheria, tetanus, and whooping cough (Tdap/Td), shingles, and pneumonia vaccines (6).

How to Live with Early-Stage Alzheimer’s Disease (2)

• Manage everyday activities: plan and organize your days by making lists and keeping a calendar up to date, address other health conditions and take all medications, take care of chores, establish a method of getting healthy meals, use public transportation or ride services.

• Make a safer home environment: get rid of unused items and furniture, install an automatic shut-off switch on the stove, set the water heater temperature to avoid burns, improve bathroom safety, carry identification with you, get safety devices to alert others, manage smoke and carbon monoxide detectors, get help with home maintenance and organization.

• Prepare for the future: prepare legal and financial matters, look into options for in-home care, plan for care when you can no longer live alone, discuss work options, find out about possible disability benefits.

• Strengthen your support groups: talk to family, friends, and neighbors who can help, discuss health care plans with healthcare providers, stay connected with technology.

Tips for caregivers and family members can be found at https://www.alzheimers.gov/life-with-dementia/tips-caregivers

Conclusion

As we get older, all of us are occasionally forgetful, but Alzheimer’s disease is not a part of normal aging. Researchers still haven’t figured out the exact causes of the disease or how to prevent and treat it successfully, but much research is being done.  We can do our part by making healthy lifestyle choices.  When you or your family member start to notice unusual behaviors, seek necessary help and find the latest treatment or management options available.

References

1. Centers for Disease Control and Prevention. Alzheimer’s Disease and Dementia https://www.cdc.gov/aging/alzheimers/index.html

2. National Institute of Aging. Alzheimer’s and Dementia. https://www.nia.nih.gov/health/alzheimers-and-dementia/tips-living-alone-early-stage-dementia

3. Alzheimer’s Association. Alzheimer’s & Dementia. https://www.alz.org/alzheimers-dementia/what-is-alzheimers

4. ScienceNewsExplores. Scientists Say: Glia https://www.snexplores.org/article/scientists-say-glia

5. De Loof, A., Schoofs, L. Alzheimer’s disease: Is a dysfunctional mevalonate biosynthetic pathway the master-inducer of deleterious changes in cell physiology? OBM Neurobiology 2019, 3(4): doi:10.21926/obm.neurobiol.1904046

6. Harris et al. The impact of routine vaccinations on Alzheimer’s disease risk in persons 65 years and older: A claims-based cohort study using propensity score matching. J Alzheimers Dis. 2023. 95(2):703.

This information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.