Alzheimer’s disease (AD) is a neurodegenerative disorder (or dementia) notable for prominent memory loss and other cognitive impairments. It is the most common form of age-related dementias. Alzheimer’s disease is diagnosed through neuropsychological assessment, in which the individual’s cognitive abilities are tested using standardized administration of paper-and-pencil tests, and neuroimaging. Initially, an individual may be diagnosed with mild cognitive impairment when deficits have not significantly disrupted daily life. As the disease progresses, an individual with Alzheimer’s disease may increasingly require assistance with activities of daily living. There is currently no cure for Alzheimer’s disease. However, there are a number of pharmacological and non-pharmacological treatments to help slow down the progression of the disease and improve quality of life.
Symptoms
Symptoms may include “rapid forgetting” (learned information is lost and cannot be retrieved with cues; e.g., forgetting names, conversations, and events), word-finding difficulties, navigational difficulties, and impairments in planning, organizing, and problem-solving. As the disease progresses, an individual with Alzheimer’s disease can start to forget one’s personal history and loved ones, become disoriented about time and place, wander and get lost, exhibit personality and behavioral changes (e.g., increased irritability or delusions), and need assistance for activities of daily living (from more complex tasks such as managing personal finances and medications to more basic such as eating, toileting, and bathing) (1). Of note, people with higher levels of education may be able employ more of their brain and cognitive resources to compensate for deficits and not show clinical signs of the disease early on. Therefore, it is not uncommon for these individuals to only show clinically significant symptomology after the disease has already progressed to more moderate and severe stages (2).
Neuropathology
Alzheimer’s disease pathology is characterized by beta-amyloid plaques and neurofibrillary tangles (twisted strands of tau proteins). These processes lead to loss of neurons (brain cells) and synapses (connections between brain cells) in the temporal (particularly the hippocampus) and parietal lobes of the brain (3). Diagnostic neuroimaging techniques, such as magnetic resonance imaging (MRI) and positron emission tomography (PET), may detect these changes in the forms of brain atrophy (loss of brain cells) and hypometabolism in these brain regions, as well as amyloid burden (2).
Prevalence
Alzheimer’s disease is the most common form of neurodegenerative illness in older adults. The current prevalence of Alzheimer’s disease is 5.5 million adults in the U.S. (2). It is projected to be 13.2 million people by 2050 due to the increasing aging population (4). The prevalence of Alzheimer’s disease increases with age. African-Americans and Hispanic-Americans are more likely to have Alzheimer’s disease compared to older white Americans. Women compose two-thirds of Americans with Alzheimer’s disease (1).
Course
An individual may be diagnosed with mild cognitive impairment (MCI) in the beginning stages of the illness when the deficits do not substantially interfere with daily life. MCI is a dynamic, transitional stage between normal cognitive status (compared to others of similar age and educational background) and dementia. People with MCI can either revert back to normal cognition (especially if the cause of the cognitive dysfunction is modifiable, such as sleep or mood disorders) or progress to dementia (2). The average disease duration for Alzheimer’s disease is four to eight years, with a large range (some may live for as long as 20 years). Alzheimer’s disease is the sixth leading cause of death in the general U.S. population and the fifth leading cause of death among those age 65 and older (1).
Treatments
There is currently no cure for Alzheimer’s disease. Pharmacological treatments such as cholinesterase inhibitors can help to slow down the progression of the disease. Although they can be used in all stages of the disease, they are most effective in the earliest stages before multisystem dysfunction (2). Non-pharmacological treatments are also utilized to improve quality of life. Cognitive and behavioral training and stimulation can improve cognition, behavior, and mood. A multisystem approach that involves cognitive and behavioral intervention as well as physical exercise and social stimulation yield the best results (5). Moreover, Transcutaneous Electrical Nerve Stimulation (TENS) can also be employed to improve Alzheimer’s disease symptomology (6).
– Michelle Chen 2018
References
- Alzheimer’s Foundation. Stages of Alzheimer’s. Retrieved from https://www.alz.org/alzheimers_disease_stages_of_alzheimers.asp.
- Loewenstein, D (2013). Assessment of Alzheimer’s disease. In L. D. Ravdin & H. L. Katzen (Eds.), Handbook on the Neuropsychology of Aging and Dementia (pp. 271-280). New York, NY, USA: Springer.
- Perrin, R, Fagan, A, & Holtzman, D (2009). Multimodal techniques for diagnosis and prognosis of Alzheimer’s disease. Nature, 461(7266), 916-922.
- Hebert, L, Scherr, P, Bienias, J, Bennett, D, & Evans, D (2003). Alzheimer disease in the US population: prevalence estimates using the 2000 census. Archives of neurology, 60(8), 1119-1122.
- Olazarán, J, Reisberg, B, Clare, L, Cruz, I, Peña-Casanova, J, Del Ser, T, & Spector, A (2010). Nonpharmacological therapies in Alzheimer’s disease: a systematic review of efficacy. Dementia and geriatric cognitive disorders, 30(2), 161-178.
- Scherder, E, Bouma, A, & Steen, A (1995). Effects of short-term transcutaneous electrical nerve stimulation on memory and affective behaviour in patients with probable Alzheimer’s disease. Behavioural brain research, 67(2), 211-219.
Alzheimer’s Disease at The Brain Clinic