Alzheimer’s disease is the most common form of dementia, a general term for loss of memory and other intellectual abilities serious enough to interfere with daily life. Alzheimer’s disease accounts for 60 – 70% of dementia cases. The majority of people with Alzheimer’s are 65 and older, however up to 5 percent of people with the disease have early onset Alzheimer’s, which often appears when someone is in their 40s or 50s.
Alzheimer’s is a progressive disease with dementia symptoms gradually worsening over a number of years. In its early stages, memory loss and cognitive impairment is mild, but with late-stage Alzheimer’s, individuals lose the ability to carry on a conversation and exhibit severe memory loss.
Costs of Alzheimer’s
It is estimated that there are nearly 44 million people worldwide that suffer from Alzheimer’s or a related dementia. The cost of caring for the 5.3 million Alzheimer’s patients in the U.S. is estimated to be $226 billion in 2015, with worldwide costs estimated at $605 billion, representing roughly 1% of the world’s GDP. Additionally, Alzheimer’s is the sixth leading cause of death in the United States. Tragically, it is estimated that the costs of Alzheimer’s will only increase in the coming decades, with over 100 million people being affected worldwide by 2040.
Genetics of Alzheimer’s
Any family history of Alzheimer’s is a risk factor for developing the disease. The risk of developing Alzheimer’s increases if more than one family member has the illness.
These epidemiological findings have led scientists to intensely study the genetics of Alzheimer’s disease. There are two types of genes that can play a role in affecting whether a person develops a disease: risk genes and deterministic genes. Risk genes of Alzheimer’s increase the likelihood that a person will develop the disease; however, risk genes do not guarantee it will occur. Deterministic genes are genes that directly cause a disease. If a person has a particular variant in a deterministic gene, they are guaranteed to develop the disease.
The most significant risk gene variant for Alzheimer’s is called apolipoprotein E-e4 (APOE-e4). APOE-e4 is one of the three common forms of the APOE gene, the others being APOE-e2 and APOE-e3. Those who inherit APOE-e4 from both parents have an even higher risk, but not a certainty. Scientists are not yet certain how APOE-e4 increases risk. In addition to raising risk, having APOE-e4 may also lower the age of onset of Alzheimer’s.
There are three known deterministic genes for Alzheimer’s: amyloid precursor protein (APP), presenilin-1 (PS-1), and presenilin-2 (PS-2). Alzheimer’s disease caused by deterministic variants is called “autosomal dominant Alzheimer’s disease (ADAD)” or “familial Alzheimer’s disease.” Typically many family members across multiple generations are affected. Age of onset also tends to be significantly earlier.
Stages of Alzheimer’s
There are three general stages of Alzheimer’s disease — mild (early-stage), moderate (middle-stage), and severe (late-stage). Alzheimer’s affects people in different ways, so each patient will experience symptoms and progress through the three general Alzheimer’s stages differently. While disease progression varies from patient to patient, symptoms of Alzheimer’s disease worsen over time. On average, a person diagnosed with Alzheimer’s typically lives for four to eight years following diagnosis, although patients can live as long as 20 years, depending on several factors including age of diagnosis.
The symptoms of Alzheimer’s disease are highly variable and therefore the listed symptoms should only be used as a general guide. Mild Alzheimer’s disease patients may encounter some common difficulties, including trouble remembering names, greater difficulty performing tasks, forgetting recently acquired information, and losing or misplacing objects. As the disease progresses, people with Alzheimer’s may exhibit unexpected emotions such as frustration or anger. During the moderate stage of Alzheimer’s, individuals may have greater difficulty performing tasks such as paying bills, although they may still remember significant details about their lives.
Physicians use several methods and tools to help determine whether a person suffering from memory problems has “possible Alzheimer’s dementia” (dementia may be due to another cause) or “probable Alzheimer’s dementia” (no other cause for dementia can be found). No single diagnostic test exists to determine whether or not a person has Alzheimer’s; it is diagnosed through a complete medical assessment by a qualified healthcare professional. Careful evaluation of a patient’s medical history, mental status testing, and neurological testing (such as MRI or PET scans) are often required to diagnose Alzheimer’s.
While a blood test exists for detection of APOE-e4, the strongest risk gene for Alzheimer’s, this test is mainly used in clinical trials to identify people at higher risk of developing Alzheimer’s. Carrying this genetic mutation does not indicate whether a person will develop Alzheimer’s. Genetic testing for APOE-e4 is controversial and should be discussed with a physician prior to testing.
There is no cure for Alzheimer’s, however treatments for symptoms are available. While current medications cannot stop the damage Alzheimer’s causes to brain cells, they may help lessen or stabilize symptoms for a limited time by affecting certain chemicals involved in carrying messages among the brain’s nerve cells. Current Alzheimer’s treatments do not halt Alzheimer’s progression, rather they temporarily slow the worsening of dementia symptoms and improve quality of life for those with Alzheimer’s and their caregivers.
The FDA has approved two types of medications — cholinesterase inhibitors (Aricept, Exelon, Razadyne) and memantine (Namenda) — to treat the cognitive symptoms of Alzheimer’s disease. Cholinesterase inhibitors are prescribed to treat symptoms related to memory, thinking, language, judgment and other thought processes and are currently approved to treat Alzheimer’s symptoms in early to moderate stages. Donepezil (Aricept) is approved to treat all stages of Alzheimer’s. Memantine (Namenda) is approved by FDA to treat moderate to severe stages of Alzheimer’s. In addition to the approved FDA therapies, some physicians prescribe vitamin E to patients for management of cognitive Alzheimer’s symptoms. Vitamin E should not be taken to treat Alzheimer’s disease except under strict supervision of a physician.
Alzheimer’s disease is an area of tremendous unmet medical need and Amylyx is passionate about bringing our therapeutic to patients in need. We hope you will support our fight against this devastating disease.
For more information regarding Alzheimer’s please visit the Cure Alzheimer’s Fund website at www.curealz.org.