Alzheimer’s disease is a progressive neurodegenerative disorder and is the most common cause of dementia. It specifically damages the brain, leading to a decline in cognitive function over time. Alzheimer’s disease is a distinct medical condition, not a normal part of the aging process.
Cognitive Impairments
Memory loss is a hallmark of Alzheimer’s disease, especially newly learned information and recent events. Individuals may repeatedly ask the same questions or forget conversations they just had. This difficulty extends to remembering names of new acquaintances or familiar family members and everyday objects as the disease progresses.
Language difficulties also become apparent, manifesting as trouble finding words, expressing thoughts clearly, or following conversations. This can make communication challenging for the person with Alzheimer’s and those around them. Patients might struggle with understanding complex sentences or articulating their needs.
Executive functions, involving planning, problem-solving, and decision-making, are significantly impaired. This can lead to difficulties managing finances, paying bills, or completing multi-step tasks like dressing. Their judgment may become compromised, affecting their understanding of safety and risks.
Visuospatial disorientation means individuals may struggle with balance, trip more often, or have trouble navigating familiar routes. They might get lost in familiar places or have difficulty orienting clothing correctly when getting dressed. These cognitive impairments profoundly impact daily life, making independent living increasingly challenging.
Pathological Brain Changes
Alzheimer’s disease is characterized by specific microscopic changes within the brain, its definitive biological hallmarks. A primary feature is the extracellular accumulation of amyloid plaques. These plaques are dense deposits of beta-amyloid protein, which clump together between nerve cells.
Another defining characteristic is the presence of neurofibrillary tangles, twisted fibers found inside neurons. These tangles are composed of hyperphosphorylated tau protein. In healthy neurons, tau helps stabilize microtubules, part of the cell’s internal transport system. In Alzheimer’s, tau changes its structure and aggregates, disrupting this system.
These pathological changes lead to neuronal loss, meaning brain cells stop functioning and eventually die. Synaptic dysfunction also occurs, where connections between nerve cells break down, impairing communication throughout the brain. As neurons continue to die, the brain can shrink, a phenomenon known as brain atrophy, and its surface wrinkles may become smoother.
Behavioral and Psychological Manifestations
Beyond cognitive decline, individuals with Alzheimer’s disease exhibit behavioral and psychological changes. Mood disturbances are common, including depression, a loss of interest in activities, and increased anxiety. Apathy, a lack of motivation or enthusiasm, can also be a noticeable symptom.
Agitation and aggression may emerge, often fluctuating. This can manifest as increased irritability, physical agitation, or verbal aggression. These expressions can be particularly challenging for caregivers and may influence decisions regarding the level of care needed.
Other manifestations include wandering, where individuals may get lost in familiar surroundings. Sleep disturbances, such as insomnia or day-night reversal, are frequently observed. Paranoia, leading to unfounded suspicions about others, or even hallucinations, where a person sees or hears things not present, can occur, especially in later stages.
Disease Progression
Alzheimer’s disease typically progresses through several stages, with symptoms worsening over time, although the rate varies for each individual. The disease often begins with a preclinical stage, where brain changes occur but no noticeable symptoms are present; this period can last for years or even decades.
The initial symptomatic phase is often referred to as mild cognitive impairment (MCI), where individuals experience more memory problems than typical for their age, but symptoms do not yet significantly interfere with daily life. For some, MCI can be an early indicator of Alzheimer’s, especially if amyloid plaques and neurofibrillary tangles are present in the brain.
In moderate stages, cognitive and behavioral challenges become more pronounced, requiring increasing assistance with daily activities. Individuals may experience deepening confusion, greater memory loss of personal history, and personality changes. They might struggle with choosing appropriate clothing or performing routine tasks without help.
In the late stages, dementia symptoms are severe, and individuals lose the ability to converse, respond to their environment, and eventually control movement. At this point, individuals become dependent on others for all personal care, including eating and hygiene. Physical abilities decline, with some losing the ability to walk or even hold up their head without support.