Alzheimer's Conditions

Alzheimer's disease is not a normal part of aging but a distinct condition. While aging increases the risk of Alzheimer’s, most age-related changes in the brain, such as tissue shrinkage, reduced neurotransmitter activity, and subtle cognitive shifts like slower processing or recalling names, are normal and not indicative of the disease. Unlike normal aging, Alzheimer’s involves significant memory loss and cognitive decline. Research shows older adults can still learn effectively with additional time and practice, retaining information once it is learned.

Mild cognitive impairment (MCI) refers to a decline in memory (amnestic MCI) or other thinking skills (non-amnestic MCI) that goes beyond normal aging but does not significantly impact daily function. Amnestic MCI primarily affects memory, while non-amnestic MCI involves difficulties in areas like attention, language, or problem-solving, with memory often remaining intact. In many people, MCI is seen as a stage between normal aging and dementia, and amnestic MCI frequently represents the earliest stages of Alzheimer’s disease. While not everyone with amnestic MCI develops Alzheimer’s disease, about 10–15% of those with amnestic MCI progress to dementia due to Alzheimer’s disease each year. MCI can be caused by other conditions as well including other neurodegenerative disorders, sleep disorders, depression, anxiety and head trauma.

With the development of drugs to treat Alzheimer's disease, and a movement toward early identification and treatment, the definition of Alzheimer's disease is changing.

AD has historically been defined as a syndrome of cognitive and functional decline with associated but variable, non-cognitive, behavioral features, and specific neuropathological and chemical changes. AD is still considered a cognitive syndrome affecting memory and at least one other area of cognition (i.e., language ability, attention and concentration, orientation, judgment, problem solving, reasoning, or the ability to perform already learned motor skills). However, it is no longer believed that everyone who develops AD will necessarily show functional decline (i.e., a diminishing ability to independently perform activities necessary for daily living, such as the ability to manage finances, cook, use a telephone, bathe, dress oneself, etc.).

For those patients who are diagnosed with AD very late in life, but early in the course of their disease, the initiation of treatment may stabilize the condition before functional decline occurs, thereby allowing an individual to live the remainder of their natural life without significant change to their way of life.

Changing Definition

The definition of AD is also changing in response to growing research on normal aging. By studying the brain tissue of normal adults, researchers have determined that brain changes associated with Alzheimer's disease (accumulation of amyloid plaques and tau tangles) start decades before the symptoms of the disease are recognized. In fact, it is hypothesized that the disease actually begins in the third, fourth, or fifth decade of life. What used to be considered a disease of advanced age is now viewed as a disease that develops across the lifespan.

There are many different conditions which cause "dementia." Dementia is a broad term used to describe a decline in cognitive function which is usually severe enough to disrupt daily life and activities. Alzheimer's disease is the leading cause of dementia among those aged 65 and older. However, unlike dementia due to stroke, where the onset of memory and thinking problems is sudden, AD results in a slow but ongoing loss of memory and thinking abilities. It is a progressive disorder which, left untreated, will continue to cause declines in cognition and functional abilities over time. 

Affects of Alzheimer's Disease

While AD always affects one of three primary domains (cognition), it may or may not impact the remaining two (functional ability and behavior). Depending on the age of the patient at the time of diagnosis, functional ability may be preserved in some cases. Most patients who live for a long time after an Alzheimer's disease diagnosis develop functional decline to variable degrees. The behavioral or "neuropsychiatric" features of AD may develop at any point in the course of the disease, or they may never develop. If behavioral symptoms of AD do occur, it does not necessarily mean that the disease is progressing. Examples of behavioral/neuropsychiatric features of AD include apathy (diminished interest, initiative, or feeling), anxiety, irritability, hallucinations (seeing or hearing things in the environment which aren't present) or delusions (holding false beliefs), disinhibition, agitation (restlessness, pacing, verbal or physical aggression), euphoria, or depression.

It is important to keep in mind that the behavioral or neuropsychiatric manifestations of AD vary widely from person to person. If behavioral symptoms occur, treatments (both non-pharmacological and pharmacological) are available, including the medications currently prescribed to treat the cognitive symptoms of AD. Originally thought to benefit cognition alone, research is demonstrating that cholinesterase inhibitors (e.g., Donepezil, Rivastigmine, Galantamine) and NMDA receptor antagonists (Memantine) may positively affect behavior and help maintain functioning for those with AD.

While having a family history of Alzheimer's can increase an individual's risk, it does not mean that the disease is guaranteed to be passed down. There are different forms of Alzheimer's, and the genetic factors involved can vary significantly.

Early-onset Alzheimer's disease occurs in individuals under the age of 65 and is sometimes linked to specific genetic mutations. Research has identified three main genes associated with early-onset Alzheimer's: PSEN1, PSEN2, and APP. If a person inherits a mutation in one of these genes, their risk of developing Alzheimer's is significantly higher, often approaching nearly 100% by their late 40s or early 50s. These genes only account for 1-5% of all cases of Alzheimer’s Disease.  Families with an extensive history of early-onset Alzheimer's should consider genetic counseling to understand their risks and options.

Most cases of late-onset Alzheimer's (onset after age 65) are not inherited. Genetic risk is influenced by different genetic factors. One of the most studied is the APOE gene, particularly the APOE ε4 allele. Everyone has two copies (alleles) of the APOE gene, one inherited from each parent. The presence of one or two ε4 alleles is associated with an increased lifetime risk of developing Alzheimer's, but it does not mean that a person will develop the disease. Research suggests that having one ε4 allele can double to triple the lifetime risk, while having two can increase risk up to twelve times compared to those without the allele. It is important to note that many people with the ε4 allele never develop Alzheimer's, indicating that other factors, including lifestyle and environmental influences, also play a crucial role in the disease's onset. 

Understanding the genetic components of Alzheimer's can be empowering for families. Genetic testing can provide insights into an individual's risk, but it also raises important questions about privacy, emotional impact, and health care decisions. For those with a family history of Alzheimer's, being proactive about health can make a difference. Engaging in a healthy lifestyle, which includes regular exercise, a balanced diet, mental stimulation, and social engagement, can potentially mitigate some risks associated with genetic predisposition.

Furthermore, ongoing research continues to explore the complexities of Alzheimer's disease and its inheritance patterns. Scientists are investigating additional genes and environmental factors that may contribute to the risk of developing the disease. This research is crucial because it helps to unravel the mysteries of Alzheimer's and offers hope for future treatments and preventive strategies. 

Alzheimer's disease is a diagnosable and treatable condition. By applying standardized diagnostic criteria, a diagnosis of AD can be made with greater than 90 percent accuracy. In fact, the current diagnostic process is capable of detecting very subtle changes in thinking or memory which may precede the clinical onset of AD. Once diagnosed, AD can be effectively treated with FDA-approved medications capable of stabilizing the symptoms of AD for several years.

By seeking evaluation early, other possible causes of memory or thinking problems can be identified and properly treated. Identifying the presence of AD early on prevents misdiagnosis and unnecessary, sometimes costly or invasive workups, procedures or medications.

If a diagnosis is made early in the course of the disease, the patient and care partners are given the opportunity to educate themselves about the condition. In turn, they can make informed choices, plan effectively for the future and use supportive services. Potential safety issues can be avoided before a crisis develops, and important social needs can be met if the condition is diagnosed early. Early diagnosis also ensures that the person with AD remains an active participant in their care by voicing preferences about important medical and financial issues, and appointing powers of attorney to ensure those preferences are upheld.

Because the current medications available for AD are intended to stabilize a patient's level of cognitive functioning at the time the medications are started, the earlier a diagnosis is made and treatment initiated, the better.

From a socio-economic standpoint, early diagnosis and treatment are cost effective. By diagnosing and stabilizing the condition at the earliest sign of difficulty, an individual is capable of functioning in much the same way he or she always has for a longer time. The use of specialized AD services, such as day activity programs, companion/escort or personal assistance services, home care, assisted living or nursing home services, or general medical care costs may be postponed or, in the case of diagnosis at a very advanced age, avoided in large part.