An estimated 5.4 million Americans have Alzheimer’s disease. Researchers expect this number to grow to 13.8 million by the year 2050. This is, for the most part, due to the aging baby boomer generation.
Today, someone in the United States develops Alzheimer’s disease every 66 seconds. By 2050, researchers expect this statistic to increase to every 33 seconds. This would mean almost one million new cases of Alzheimer’s disease per year.
In 2013, official death certificates recorded 84,767 deaths from Alzheimer’s disease. According to the National Institute on Aging, it is the sixth leading cause of death in the United States.
It also makes Alzheimer’s disease the fifth leading cause of death in Americans aged 65 or older. Researchers believe deaths from Alzheimer’s are higher than what’s on death certificates.
Let’s put things in perspective here. Between 2000 and 2013, deaths from stroke, heart disease, and prostate cancer decreased by 23%, 14%, and 11%. Deaths from Alzheimer’s disease increased by 71%.
In 2015, over 15 million unpaid caregivers provided care to people with Alzheimer’s. This totals 18.1 billion hours of care. This is a contribution valued at more than $221 billion.
Per person, Medicare payments for Alzheimer’s disease total 2.5 times greater than patients without this condition. Total payments in 2016 for health care, long term care, and hospice services for patients with dementia totaled $236 billion.
As you will see, Alzheimer’s dementia places a significant burden on individuals and families. This is due to reduced cognitive ability and physical limitations. They also place a financial burden on families. People often have to take money out of their retirement savings. They may even cut back on buying food and reduce their own health care services.
What is Alzheimer’s Disease?
Alois Alzheimer was the first doctor to describe Alzheimer’s disease. He did this in 1906 about a patient he had first encountered in 1901.
Alzheimer’s disease is a neurodegenerative disorder with insidious onset and slow progression. It involves diffuse brain dysfunction. Alzheimer’s disease is a progressive form of dementia.
Dementia is a broad term for diseases that affect memory. They also affect thinking and behavior. These changes must interfere with daily living to qualify as dementia.
Alzheimer’s disease accounts for 60 to 80 percent of dementia cases. Most patients get a diagnosis after age 65. Before this age is early-onset Alzheimer’s disease. There is no cure for Alzheimer’s disease. There are treatments that slow its progression.
There is no single outcome for patients with Alzheimer’s disease. Some live a long time. Some have mild cognitive damage. Others experience rapid symptom onset. Others have a fast progression of the disease. Each case is specific to the individual.
There are two hallmark signs that characterize Alzheimer’s disease. The first is the deposition of beta-amyloid neuritic plaques. The second is neurofibrillary tangles of hyperphosphorylated tau proteins.
Other characteristics of Alzheimer’s dementia include the following:
- Disruption of the blood-brain barrier
- Oxidative stress
- Mitochondrial impairment
- Neuroinflammation
- Hypometabolism
Neurodegeneration that occurs in Alzheimer’s includes atrophy and loss of nerve cells. This is due to toxic amyloid oligomers and proteins outside the nerves.
It is also because of the neurofibrillary tangles consisting of hyperphosphorylated tau proteins. Lowered glucose metabolism in the cerebrum contributes to this as well. So too, do a dysfunction of the synapses and mitochondria.
In Alzheimer’s disease, changes occur in the amyloid precursor protein cleavage. There are also changes in the hyperphosphorylated tau protein aggregation. These problems reduce the strength of synapses. You can lose synapses, and nerves can start to degenerate.
Alzheimer’s patients have a decrease in acetylcholine levels. They also experience reduced cerebral blood flow.
Alzheimer’s disease is the most common cause of dementia. It is a growing health concern globally. It has huge implications for individuals as well as for society at large. Alzheimer’s disease causes significant individual morbidity and mortality. It also has a great economic impact on the health care system.
Dementia vs. Alzheimer’s
Alzheimer’s disease and dementia are two terms that people tend to use interchangeably. This is incorrect. These are two different conditions. Alzheimer’s is a type of dementia.
Alzheimer’s is one of several possible causes of dementia. Alzheimer’s is a subtype of dementia. It is the most common of the dementia subtypes. Other subtypes of dementia include:
- Vascular dementia
- Dementia due to Lewy bodies
- The dementia-Parkinson complex
- Frontotemporal dementia
- Other related dementia
The term dementia comes from the Latin root demens. This means “being out of one’s mind.” As neuropathology progressed, they fragmented dementia into various conditions. Dementia separated from Alzheimer’s disease in 1906.
Dementia is any decline in cognition that interferes with independent daily functions. Dementia is a syndrome, rather than one disease.
The causes of dementia could be primary neurologic, neuropsychiatric, or other medical conditions. It is common for many disease processes to contribute to one patient’s dementia syndrome.
One difference between dementia and Alzheimer’s is the risk factor of sex. Females are at increased risk of developing Alzheimer’s disease. Males are at greater risk of developing vascular dementia.
Causes
Molecular studies in rodent models suggest astrocytes contribute to neuroinflammatory and neurodegenerative processes. These processes cause Alzheimer’s disease.
Several practitioners have attempted to treat Alzheimer’s disease, using anti-amyloid strategies. These have given disappointing results. The “amyloid cascade hypothesis” alone cannot explain Alzheimer’s disease.
There is some research to show that infections may be factors in Alzheimer’s disease. Inflammation is one of the first lines of defense our bodies have against infections.
Inflammation plays a crucial role in the regeneration and repair of brain tissue. A healthy inflammatory response resolves the inflammation after eliminating harmful stimuli. When the inflammatory reaction goes beyond this, it can damage surrounding normal cells.
The relationship between infections and Alzheimer’s disease is a topic of debate. Emerging evidence shows the following infections are possibly implicated in Alzheimer’s disease:
- Human Herpesvirus 1 (HHV-1)
- Cytomegalovirus (CMV)
- Human herpesvirus 2 (HHV-2)
- Hepatitis C
- Porphyromonas gingivalisTreponema denticola
Recent investigations show chronic viral, bacterial, and fungal may lead to Alzheimer’s disease.
Risk factors
One of the most significant risk factors for Alzheimer’s disease is older age. Alzheimer’s is much more common in older adults. Research shows the incidence and prevalence of dementia increase exponentially from age 65 onwards.
Other risk factors for Alzheimer’s disease include the following:
- Smoking
- Excessive alcohol use
- Poor diet
- Obesity
- Type 2 diabetes
- Cardiovascular disease
- High blood pressure in midlife
- Dyslipidemia (high cholesterol)
- Cerebrovascular lesions
- Use of benzodiazepines
- Being female
- Stress
- Head injury
Obesity is a major risk factor because it induces adipokine dysregulation. This consists of the release of proinflammatory adipokines and decreased release of anti-inflammatory adipokines.
Another huge risk factor is your genes. In fact, approximately 70% of the risk of developing Alzheimer’s disease is due to your genetics. Genetic studies show the risk of developing Alzheimer’s associates with several genes.
These genes are APOE, APOJ, and SORL. These genes are mostly expressed by glial cells. These include astrocytes, microglia, and oligodendrocytes.
Family history is important, as well. If you have an immediate family member with Alzheimer’s disease, you are more likely to get it as well.
Certain drugs can increase your risk of Alzheimer’s disease. Particularly those that alter your microbiota composition. This contributes to dysbiosis. This increases intestinal permeability and can cause the leaky gut syndrome.
The risk of developing Alzheimer’s is lower in patients with higher education. This is also true of those with occupational attainment. The concept of cognitive reserve explains this. Cognitive reserve explains for differences between individuals in susceptibility to age-related brain changes or pathology related to Alzheimer’s disease.
Some people tolerate more of these changes than others and still maintain function. There are two types of reserve: brain reserve and cognitive reserve. Brain reserve is a difference in brain structure that increases tolerance to Alzheimer’s disease.
Cognitive reserve refers to differences between individuals in how tasks are performed. Cognitive reserve allows some people to be more resilient to brain changes.
If you have risk factors listed above, this does not mean that you will develop Alzheimer’s disease. It simply raises your risk level. To learn more about your risk of Alzheimer’s disease, speak with your health care provider.
Symptoms
The main symptom of Alzheimer’s disease is the reduced ability to encode and store new memories. This memory loss is more significant than what you would see with normal aging.
Along with memory problems come language and visuospatial skills deficiencies.
There are also behavioral disorders such as apathy, aggression, and depression. The progressive changes in cognition and behavior usually occur in later stages.
Disturbed sleep is also a major problem in patients with dementia. Insomnia and other sleep disturbances are common in patients with Alzheimer’s disease.
Metabolic, vascular, and inflammatory changes occur in Alzheimer’s disease. Comorbid pathologies are also critical components of the disease process.
Symptoms of Alzheimer’s disease may include:
- Memory loss
- Difficulties with everyday tasks
- Decreased personal hygiene
- Difficulty problem solving
- Trouble writing or speaking
- Decreased judgment
- Mood and personality changes
- Disorientation with time or place
- Withdrawal from friends, family, and community
Stages
Alzheimer’s disease occurs in three stages. These three stages are preclinical, mild cognitive impairment, and dementia. Alzheimer’s disease is a continuum.
Several pathological changes can happen decades before Alzheimer’s symptoms start to occur. There are no motor, sensory, or coordination deficits early on in the disease. The preclinical stage has the highest potential for Alzheimer’s disease research.
Diagnosis
Evaluation of a suspected case involves structured history from caregiver and patient. There will also be a physical exam and testing. Testing is usually laboratory and neuroimaging. These tests are done to find out what level of impairment exists. It also helps determine the cognitive-behavioral syndrome and to diagnose the potential cause.
The diagnosis of Alzheimer’s disease requires memory loss and impairment of cognitive function. The final diagnosis is based on the patient’s clinical presentation. They also look at fluid and imaging biomarkers. In patients with Alzheimer’s disease, the cerebrospinal fluid is positive for biomarkers. They conduct neuroimaging with PET scan.
Potential biomarkers to confirm Alzheimer’s disease include the following:
- Oxidative stress
- Metal ions
- Vascular disorders
- Protein dysfunctions
- Alterations in the mitochondrial populations
Prevention
By the time Alzheimer’s disease is usually diagnosed, there is a loss of brain cells. There are neuropathological lesions that could damage several regions of the brain.
The following lifestyle factors can help to prevent Alzheimer’s disease:
- Active social engagement
- Physical exercise
- Mentally stimulating activity
- Caloric restriction
Controlling vascular risk factors can be helpful. In fact, researchers have stated that this is optimal in long term interventions. Socialization and mentally stimulating activities help to reduce the risk or postpone the clinical onset of Alzheimer’s disease.
Clinical trials show omega 3 fatty acid supplementation affects mild cognitive decline.
The Mediterranean diet modifies type 2 diabetes and obesity. Both of these are possible risk factors for Alzheimer’s disease. The Mediterranean diet includes fruits, vegetables, olive oil, fish, and moderate wine intake. These foods are helpful because they provide vitamins, polyphenols, and unsaturated fatty acids.
The Mediterranean diet can help to reduce oxidative stress. Unsaturated fatty acids help to reduce the inflammatory response. This results in a lower expression and lower production of proinflammatory cytokines.
Polyphenols and unsaturated fatty acids affect the vascular endothelium, protecting the cardiovascular system. This reduces cardiovascular risk factors like dyslipidemia, high blood pressure, and metabolic syndrome.
Researchers conducted a systematic review. The goal was to identify risk factors associated with Alzheimer’s disease. The authors considered primary studies reporting on non-genetic risk factors. They identified 65 relevant primary studies on confirmed Alzheimer’s disease. Researchers found that the following factors decreased risk of Alzheimer’s disease:
- Statin drugs
- Light to moderate alcohol consumption
- Compliance with a Mediterranean diet
- Higher educational attainment
- Exercise
- Cognition stimulating activities
- APOE E2
Prospective studies have found physical inactivity is a common preventable risk factor. Higher physical activity levels mean reduced risk.
Alzheimer’s care
Alzheimer’s care should involve psychoeducation. It should also have shared goal-setting and decisions between both patient and caregiver. Currently, treatment is targeted toward managing symptoms. Trials are underway that aim to reduce the production and burden of Alzheimer’s on the brain.
Alzheimer’s disease is a significant public health issue. Yet only five medical treatments are available. All five of these act to control symptoms rather than alter the disease course. Researchers state that a single cure for Alzheimer’s disease is unlikely to be found.
The good news? Practitioners are well-positioned to alleviate suffering and treat contributing conditions. They can also prescribe medications to improve cognitive, neuropsychiatric, and motor symptoms. Practitioners are also able to promote evidence-based brain-healthy behaviors. These can help to improve the overall quality of life for AD patients and families.
Exercise is a potential treatment for preclinical Alzheimer’s and late-stage Alzheimer’s disease. Exercise helps to improve brain blood flow, increase the volume of the hippocampus, and improve neurogenesis.
The exercise shows improvement in cognitive function, decreases neuropsychiatric symptoms, and slows decline in activities of daily living. Exercise also has fewer side effects and better adherence compared to medications.
Pharmacological treatments for Alzheimer’s disease fall under two categories: symptomatic treatments and etiology-based treatments. Symptomatic treatments include acetylcholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists. Etiology-based treatments include secretase inhibitors, amyloid binders, and tau therapies.
The cholinesterase inhibitors currently approved are Donepezil, rivastigmine, and galantamine. They treat mild, moderate, and severe Alzheimer’s disease. These medications show benefits on cognition, activities of daily living, behavior, and overall clinical rating.
Memantine is a symptomatic treatment for moderate to severe Alzheimer’s disease. It has a small effect on cognition, activities of daily living, behavior, and overall clinical rating.
Vitamin E has antioxidant properties and may be useful in some patients with Alzheimer’s disease who do not have vascular risk factors.
When combined, pharmacologic and nonpharmacologic therapies reduce the symptoms of Alzheimer’s disease. They also reduce clinical progression and care burden.
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Conclusion
If you suspect you or a loved one may have Alzheimer’s disease, it is important to seek care right away. This is crucial because once symptoms become apparent, damage to nerve cells has already occurred. As with any disease process, it is always easier to prevent problems than it is to treat them.
Alzheimer’s disease affects such a large amount of people in such a detrimental way. And yet, only symptomatic treatment exists. If you want to prevent Alzheimer’s disease, it is a good idea to exercise, socialize, eat a Mediterranean diet, and keep mentally stimulated. You may not be able to control your genetics, but you can reduce your risk factors. If you are curious about your genes, it is possible to have genetic testing done.
Speak to your health care provider to see what treatment options are best for you. Keep in mind that a combination of pharmacologic and nonpharmacologic therapies can be effective.
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