Dementia and Cognitive Decline What Actually Happens in the Brain

When people worry about dementia, they are often worrying about the wrong thing — or, at least, about a blurry composite of several different things. They conflate it with normal forgetting, with aging in general, with Alzheimer's specifically, or with an inevitable fate that arrives with gray hair. Untangling those confusions is not merely academic. It changes what you notice, when you seek help, what you can do about your own risk, and how you understand a diagnosis in someone you love. So this guide takes the topic seriously and in depth, moving from the broadest distinction — decline versus dementia — through the specific diseases, their signs, their causes, and finally to the genuinely hopeful science of prevention.

One organizing idea runs through everything that follows: dementia is, at bottom, biology. Behind every symptom is a physical process in the brain — proteins misfolding and spreading, blood vessels failing, particular circuits degenerating — and the clearest way to understand dementia is to understand those processes, then see how they surface as the changes people experience. That is the lens this guide takes. Throughout, claims are tied to the primary medical literature and major consensus reports, so you can see where the evidence comes from and distinguish what is well established from what remains uncertain. One thing this guide is not is a substitute for medical evaluation: diagnosing dementia, and telling its types apart in a real person, is the work of a qualified clinician, and the aim here is to illuminate the science beneath that work.

§I.Cognitive decline versus dementia: the crucial distinction

The single most useful idea to hold onto is that cognitive change exists on a spectrum, and dementia is only its most severe region. At one end is the ordinary, expected slowing that accompanies healthy aging. In the middle is a stage where thinking has measurably slipped but daily life still functions. At the far end is dementia, where the decline is serious enough to compromise a person's independence. Treating this as a spectrum, rather than a single on-off switch, is how clinicians think about it — and it prevents both false alarm and false reassurance¹².

"Cognitive decline," then, is a broad description, not a diagnosis. It simply means that thinking abilities — memory, attention, language, reasoning, and so on — have worsened relative to a person's former level. That worsening can be trivial and normal, it can be a distinct but non-disabling condition (mild cognitive impairment), or it can be part of dementia. The essential logic is a one-way street: all dementia involves cognitive decline, but the great majority of cognitive decline is not dementia. Keeping that asymmetry in mind is the antidote to the common fear that any lapse of memory signals the beginning of the end.

§II.What dementia actually is

Dementia is best understood as a syndrome — a recognizable cluster of symptoms — rather than a specific disease. Formally, it denotes an acquired, typically progressive decline in one or more domains of thinking (such as memory, language, or judgment) that is severe enough to interfere with a person's ability to carry out everyday activities and represents a decline from a previous level of function¹. In current diagnostic language, this is termed "major neurocognitive disorder," with "mild neurocognitive disorder" describing the less severe stage that does not yet impair independence¹.

Two features of that definition deserve emphasis. First, dementia is acquired and represents a decline — it is not lifelong low ability but a loss of previously held function, which is what distinguishes it from conditions like intellectual disability. Second, it is defined partly by impact: the threshold that separates dementia from milder decline is whether the person can still manage the tasks of independent daily life, such as managing finances, medications, and appointments². Because dementia is a syndrome, the next natural question is always what is causing it — and there are many possible answers, which is what the sections on types address.

The scale is sobering. Worldwide, more than 55 million people were living with dementia as of the early 2020s, with nearly 10 million new cases each year, and it ranks among the leading causes of death and of disability in older adults globally¹⁴. Because dementia risk rises steeply with age and populations are aging, those numbers are projected to grow dramatically — one widely cited analysis forecast a rise from roughly 57 million cases in 2019 to about 153 million by 2050⁴. This trajectory is precisely why the science of prevention, covered later, has become so urgent.

One further distinction prevents a consequential mix-up: dementia is not the same as delirium. Delirium is an acute, usually reversible state of confusion that develops over hours to days — often triggered by infection, medication, dehydration, or hospitalization — and it characteristically fluctuates and disrupts attention². Dementia, by contrast, develops gradually over months to years and is generally progressive. The two can coexist, since people with dementia are more prone to delirium, but mistaking a treatable delirium for irreversible dementia (or the reverse) can lead to serious errors. It is one more reason that a sudden change in thinking, in particular, warrants prompt medical attention rather than assumption.

§III.Cognitive decline: from normal aging to mild cognitive impairment

To recognize what is abnormal, you first have to know what is normal — and some cognitive change with age is entirely expected. As the brain ages, processing speed tends to slow, multitasking becomes a little harder, and retrieving a specific word or name can take longer. Certain kinds of memory become slightly less reliable, even as accumulated knowledge and vocabulary typically hold steady or improve into later life. These changes reflect the normal biology of the aging brain rather than disease (for the underlying biology, see how the brain changes with age). The hallmark of normal age-related change is that it is mild, stable or very slowly progressive, and — critically — it does not stop a person from living independently.

Beyond normal aging lies mild cognitive impairment (MCI), a clinically recognized stage that is the frequent focus of concern. In MCI, cognitive decline is greater than expected for a person's age and is often noticeable to the individual or those around them, and it can be detected on testing — yet the person remains functionally independent, still able to manage the essential tasks of daily life¹². MCI is not dementia, but it is an important category because it substantially raises the risk of progressing to dementia. Estimates vary, but people with MCI convert to dementia at a rate on the order of 10–15% per year in clinical samples, far higher than the rate in the general older population¹².

Two nuances make MCI genuinely important rather than merely a source of anxiety. First, MCI does not inevitably progress: a meaningful proportion of people with MCI remain stable, and some even revert to normal cognition, particularly when the impairment stems from treatable contributors such as medication effects, sleep problems, thyroid dysfunction, or depression¹². Second, MCI is often the stage at which reversible causes can be found and addressed, and at which lifestyle and vascular risk factors are most worth attention — which is why an accurate evaluation matters rather than assuming the worst. There is also a still-earlier stage, "subjective cognitive decline," in which a person notices a slippage that testing cannot yet confirm; it is an active area of research as a possible very early signal in some people.

§IV.Memory loss: what is normal and what is not

Because memory is the faculty people watch most anxiously, it deserves its own treatment — and here the difference between normal and concerning is often one of kind, not just degree. Occasionally forgetting where you put your keys, blanking momentarily on an acquaintance's name, or walking into a room and losing your train of thought are near-universal experiences that reflect normal aging, distraction, stress, or poor sleep far more often than disease². The reassuring pattern is forgetting a detail and later recalling it, or recognizing that you have forgotten something at all.

The concerning pattern is qualitatively different. It is not misplacing the keys but forgetting what the keys are for; not blanking on a name but failing to recognize a close family member; not losing your train of thought but repeatedly asking the same question within minutes, unaware it has already been answered. Memory loss becomes a warning sign when it disrupts daily life, when it steadily worsens over months, and especially when it is accompanied by other changes such as disorientation, difficulty with familiar tasks, or trouble with language². The direction and impact of the change matter more than any single lapse.

It also helps to know that "memory" is not one thing. Episodic memory (recall of specific personal events) is typically the most vulnerable early in Alzheimer's disease, whereas working memory (holding information in mind for a moment) and processing speed are more affected in vascular and some other dementias, and procedural memory (how to perform practiced skills) is often preserved until late¹³. This is why different diseases produce different early memory complaints — and why the pattern of what is failing, not merely that something is failing, is a clue clinicians use to identify the cause.

§V.How the biology shows up as symptoms

Dementia's symptoms are not arbitrary; each is the downstream consequence of particular brain systems being damaged. Seen through that lens — a symptom as the visible signature of an underlying biological process, not an item on a checklist — they become both clearer and more meaningful. They still fall into three broad groups: cognitive symptoms, behavioral and psychological symptoms, and functional decline.

Cognitive symptoms are the classic features. Beyond memory loss, they commonly include difficulty finding words or following conversation (language); trouble with planning, organizing, and problem-solving (executive function); getting lost or confused about time and place (orientation and visuospatial ability); impaired judgment and reasoning; and difficulty performing tasks that were once automatic². Which of these dominates, and in what order they appear, depends heavily on the underlying disease and which brain regions it strikes first.

Behavioral and psychological symptoms are less discussed but enormously important, affecting most people with dementia at some point and often causing the greatest distress for families. They include depression, anxiety, and apathy (a flattening of motivation and interest); agitation and aggression; suspiciousness and, in some conditions, hallucinations or delusions; sleep disturbances; and changes in personality². In some dementias these behavioral changes are not a late complication but the earliest sign, which can lead to misdiagnosis as a psychiatric condition.

Functional decline is the feature that, by definition, separates dementia from milder cognitive impairment. It progresses in a fairly characteristic order: first the complex "instrumental" activities of daily living become difficult — managing finances, medications, transportation, and appointments — and later the basic activities of daily living, such as dressing, bathing, and eating, require help¹. Clinicians often describe dementia's course in broad stages — early (mild), middle (moderate), and late (severe) — reflecting this widening gap between what a person can manage alone and what they need help with, though the pace and pattern vary considerably by individual and by disease.

Because different diseases attack different brain systems first, the pattern of symptoms is itself a window into the underlying biology — and mapping the major symptom types back to the brain systems that produce them is close to how clinicians reason about which disease is most likely²:

§VI.The major types of dementia

Because dementia is a syndrome with many causes, "types of dementia" really means the different diseases that produce it. Several are common enough, and distinct enough, to be worth knowing. It is worth stressing at the outset that these are not always separate: especially in older people, more than one process is frequently present at once, a situation called mixed dementia⁸.

Alzheimer's disease is by far the most common cause, responsible for roughly 60–70% of dementia cases¹⁴. At the biological level, it is characterized by the abnormal accumulation of two proteins in the brain — amyloid-beta, which forms plaques between neurons, and tau, which forms tangles inside them — accompanied by neuronal loss and brain atrophy that typically begins in and around the hippocampus, the brain's memory hub^7,13. Clinically, this pathology usually produces a gradual, insidious decline led by episodic memory — difficulty forming new memories, repeating questions, misplacing items — with language, reasoning, and orientation eroding as it spreads. Its single greatest risk factor is age, and its best-known genetic risk factor is the APOE ε4 gene variant, which raises risk without guaranteeing the disease¹³. Alzheimer's is covered here as one type among several; its memory-led, slowly progressive pattern is the template most people picture when they think of dementia, but it is not the only one.

This is the natural place to clear up the single most common source of confusion in the whole subject: the difference between dementia and Alzheimer's disease. The two are routinely used as synonyms, but they are not the same. Dementia is the umbrella syndrome — the collection of symptoms; Alzheimer's is one specific disease that produces it, the most common cause but far from the only one¹⁴. Every person with Alzheimer's dementia has dementia, yet a large share of people with dementia have something other than Alzheimer's — vascular disease, Lewy bodies, frontotemporal degeneration, or a mixture of these. The relationship is like that between "fever" and the particular infection behind it: the fever is the manifestation, the infection one of many possible causes. Getting this right matters practically, because the different causes carry different early signs, different courses, and sometimes different treatments — so "it is dementia" is the start of the diagnostic question, not the end of it.

Vascular dementia is generally the second most common cause, arising from impaired blood flow to the brain — the subject of its own section below¹¹. Dementia with Lewy bodies is a major cause marked by fluctuating attention, visual hallucinations, and movement changes, also detailed in its own section¹⁰.

Frontotemporal dementia (FTD) is less common overall but a leading cause of dementia in people under 65, and it differs strikingly from Alzheimer's³. Because it targets the frontal and temporal lobes rather than the memory system first, its earliest symptoms are often not memory loss at all but profound changes in behavior and personality — loss of empathy, socially inappropriate conduct, apathy, or compulsive behaviors — in the "behavioral variant," or a progressive breakdown of language in the "primary progressive aphasia" variants³. Its onset in midlife and its behavioral presentation mean it is frequently mistaken at first for a psychiatric disorder such as depression or a midlife crisis, and accurate diagnosis can take years.

Mixed dementia deserves particular emphasis because it may be the rule rather than the exception in later life. Autopsy studies consistently find that many older people with dementia have more than one underlying pathology — most commonly Alzheimer's changes together with vascular damage, but other combinations occur⁸. This matters practically: it means the neat categories are somewhat idealized, that a person's symptoms may reflect several processes, and that addressing vascular risk factors may help even when Alzheimer's pathology is also present.

Finally, and importantly, some cognitive decline that looks like dementia stems from potentially reversible causes — which is one of the strongest reasons to seek evaluation rather than assume the worst. Deficiency of vitamin B12, thyroid dysfunction, depression (sometimes called "pseudodementia" when it mimics cognitive impairment), side effects of medications, sleep disorders, and conditions such as normal pressure hydrocephalus can all produce dementia-like symptoms that may improve substantially when the underlying problem is treated². Identifying these treatable contributors is a routine and vital part of a proper diagnostic workup.

§VII.Vascular dementia in depth

Vascular dementia (also called vascular cognitive impairment in its broader form) is cognitive decline caused by conditions that reduce or block blood flow to the brain, depriving brain tissue of the oxygen and nutrients it needs¹¹. As the second most common cause of dementia after Alzheimer's, and a frequent partner in mixed dementia, it is central to understanding the whole landscape — and, because its causes overlap so heavily with those of heart disease and stroke, it is also among the most preventable⁵.

Its causes span a spectrum of vascular injury. At one extreme, a single large stroke in a critical region, or several strokes accumulating over time, can produce dementia in a relatively abrupt or stepwise fashion¹¹. More common, and more insidious, is small vessel disease: chronic damage to the brain's tiny blood vessels, often driven by long-standing high blood pressure and diabetes, which injures the deep white matter and produces a gradual decline that can closely resemble Alzheimer's⁵. Because of this range, vascular dementia does not have one single course — it can appear suddenly after a stroke, worsen in discrete steps, or progress smoothly, depending on the underlying vascular process.

The pattern of symptoms often differs from Alzheimer's in an instructive way. Where Alzheimer's typically leads with memory, vascular dementia frequently leads with slowed thinking and executive dysfunction — difficulty with planning, organizing, concentrating, and making decisions — because small vessel disease disrupts the white-matter connections that coordinate these frontal-lobe functions¹¹. Memory may be relatively better preserved early on, while processing speed suffers. Physical signs are also more common, including problems with walking and balance, and mood changes such as depression and apathy are frequent¹¹. Recognizing this "subcortical" profile — slow, effortful thinking with gait and mood changes — helps distinguish it, though overlap with other dementias is substantial.

The most important message about vascular dementia is a hopeful one: its risk factors are largely the same modifiable ones that drive cardiovascular disease — high blood pressure, diabetes, high cholesterol, smoking, obesity, and physical inactivity^5,9. This is the concrete basis for the frequently repeated principle that what is good for your heart is good for your brain. Controlling blood pressure in particular has emerged as one of the most promising strategies for protecting the brain's blood supply, and it is a cornerstone of the prevention approach discussed below and in our guide to reducing dementia risk.

§VIII.Lewy body dementia in depth

Lewy body dementia is an umbrella for two closely related conditions — dementia with Lewy bodies (DLB) and Parkinson's disease dementia — that share a common biology and, together, represent one of the more common degenerative causes of dementia¹⁰. Its underlying pathology is the abnormal accumulation of a protein called alpha-synuclein into deposits known as Lewy bodies inside neurons — the same protein and deposits found in Parkinson's disease, which is why the two conditions are so intertwined¹⁰.

What makes Lewy body dementia distinctive — and frequently misdiagnosed — is its particular constellation of core features, which differ markedly from Alzheimer's¹⁰. Four stand out. First, fluctuating cognition: alertness and attention can vary dramatically from hour to hour or day to day, so a person may be lucid at one moment and confused the next, in a way that can be mistaken for delirium. Second, recurrent visual hallucinations that are typically detailed and well-formed — often of people or animals — appearing early in the illness. Third, parkinsonism: movement symptoms resembling Parkinson's disease, such as slowness, rigidity, tremor, and a shuffling gait. Fourth, REM sleep behavior disorder, in which a person physically acts out their dreams during sleep — a symptom that can precede other signs by years and is a strong early clue¹⁰.

The distinction between DLB and Parkinson's disease dementia is made largely by timing. When cognitive symptoms appear first, or within about a year of the movement symptoms, the condition is generally classified as dementia with Lewy bodies; when a person has established Parkinson's disease for years and later develops dementia, it is termed Parkinson's disease dementia¹⁰. Because the biology is shared, this "one-year rule" is a practical convention rather than a sharp biological boundary.

One feature of Lewy body dementia is important enough to state on its own, because it is a genuine safety issue: people with the condition can be severely and dangerously sensitive to certain antipsychotic medications, which are sometimes prescribed for the hallucinations or agitation that occur in dementia¹⁰. In people with Lewy body dementia, some of these drugs can provoke severe reactions, including profound worsening of movement and alertness. This is a central reason that distinguishing Lewy body dementia from other types is not a mere academic exercise but can directly affect safety and treatment — and why any medication decisions in dementia should be made carefully with a knowledgeable clinician.

§IX.What causes dementia? Risk factors, changeable and not

Understanding what raises the risk of dementia is where the topic turns from description to agency — because while some risk factors are fixed, a substantial share are not. It is useful to separate the two.

The non-modifiable factors are real and significant. Age is by far the strongest: the risk of dementia roughly doubles every five years or so after 65, though it is essential to repeat that dementia is not a normal or inevitable consequence of aging — most older adults never develop it¹⁴. Genetics plays a role that ranges from modest to decisive: for the common late-onset form, gene variants such as APOE ε4 raise risk without determining fate, while rare inherited mutations can cause early-onset familial forms directly¹³. Family history and certain other fixed factors also contribute. These cannot be changed — but they are only part of the story.

The modifiable factors are where the hopeful, and genuinely actionable, science lies. In its landmark reports, the Lancet Commission on dementia prevention concluded that a large fraction of dementia worldwide is potentially preventable by addressing risk factors across the life course. The 2020 report identified 12 such factors accounting for around 40% of cases; the updated 2024 report added two more — untreated vision loss and high LDL cholesterol — bringing the total to 14 factors and the estimated preventable fraction to roughly 45%^8,9.

Those 14 factors span life's stages: less education in early life; hearing loss, high LDL cholesterol, depression, traumatic brain injury, physical inactivity, diabetes, smoking, high blood pressure, obesity, and excessive alcohol in midlife; and social isolation, air pollution, and untreated vision loss in later life⁹. Several themes run through the list — protecting the brain's blood supply (blood pressure, cholesterol, diabetes, smoking), staying cognitively and socially engaged (education, social contact), preserving the senses that feed the brain (hearing and vision), and general brain-healthy living (activity, not smoking, moderate alcohol). Two clarifications keep this honest: the ~45% figure is a theoretical population estimate of what could be prevented if these factors were eliminated, not a personal guarantee; and these are risk factors, meaning they shift the odds rather than determine any individual's outcome⁹. Even so, the practical takeaway is powerful — much of dementia risk is not fixed.

A subtle but important implication of this life-course view is that dementia risk is shaped across decades, not only in old age. Some of the most influential factors — education in early life, and blood pressure, hearing, and cholesterol in midlife — exert their effects long before any symptoms would appear, which means prevention is not solely a concern for the elderly⁹. It is therefore rarely too early to attend to these factors and, encouragingly, rarely too late: the evidence indicates that addressing modifiable risks even in later life can still shift the odds. The most effective strategy targets several factors together and sustains them over time, rather than relying on any single decisive intervention⁸.

§X.How dementia is diagnosed

There is no single test for dementia. Diagnosis is a clinical process of assembling evidence and, crucially, of ruling things out — which is why a proper evaluation is worth seeking rather than self-diagnosing from a symptom list². It typically combines several elements.

The foundation is a careful history — from the person and, importantly, from someone who knows them well, since insight can be affected — documenting what has changed, when, and how it affects daily life. This is paired with cognitive testing, ranging from brief bedside screens to detailed neuropsychological assessment, which characterizes the pattern and severity of impairment². A physical and neurological examination and laboratory tests are used to identify the reversible and contributing causes discussed earlier — checking, for example, thyroid function and vitamin B12 — and to assess vascular and other health factors².

Brain imaging adds further information: structural scans (MRI or CT) can reveal patterns of atrophy, evidence of strokes or small vessel disease, and help exclude other conditions, while specialized scans (such as certain PET scans) can detect features associated with specific diseases². The field is also moving rapidly toward biomarkers — measures of the underlying disease biology, historically from cerebrospinal fluid or amyloid PET, and increasingly from blood tests — that can help identify Alzheimer's pathology specifically and are reshaping how the disease is defined and detected⁶. The overall goals of this workup are threefold: to confirm whether dementia is present, to identify its most likely cause or causes, and to catch anything treatable — which is exactly why timely medical evaluation is valuable.

A word on timing: seeking evaluation early, rather than waiting, carries real advantages. It maximizes the chance of finding and treating reversible contributors, opens access to treatments and support that work best when started sooner, gives the person time to plan while their capacity to do so is greatest, and often relieves the corrosive anxiety of uncertainty — even when the news is hard². Fear of the answer is understandable and is one of the main reasons people delay, sometimes for years; but delay rarely helps, and frequently costs.

§XI.Treatment and management

An honest account of treatment must hold two truths at once: for most causes of dementia there is currently no cure, and yet a great deal can still be done to help people live better with the condition². It is not a diagnosis beyond help, even where it is beyond cure.

On the medication side, several drugs can modestly help symptoms in some people. Cholinesterase inhibitors and memantine are long-established treatments that can produce modest improvements in cognition or slow symptomatic decline for a time in Alzheimer's and some other dementias, without altering the underlying disease². More recently, a new class of anti-amyloid antibody treatments for early Alzheimer's has been developed that removes amyloid from the brain and can modestly slow decline — but these carry meaningful risks and costs, offer benefits that are real yet limited in magnitude, and remain the subject of active debate about how much they help in practice^7,13. The realistic framing is that current drugs help at the margins rather than reverse the disease.

Just as important, and sometimes more so, is non-drug management. This includes structured support for the behavioral and psychological symptoms of dementia (often through environmental and behavioral strategies rather than medication, given the risks noted for Lewy body dementia); attention to physical health, sleep, hearing, and vision; cognitive and social engagement; and — centrally — support for caregivers, whose wellbeing profoundly shapes outcomes^2,8. The 2020 and 2024 Lancet Commissions emphasize that good dementia care — not only medical treatment — substantially improves the lives of people with dementia and their families⁹. Living well with dementia is a genuine and achievable goal.

§XII.Reducing your risk

If there is one section to carry away, it is this one — because it is where the evidence is most empowering. You cannot change your age or your genes, but the research is now clear that a substantial share of dementia risk runs through factors you can influence, and that acting on them is worthwhile at any age⁹. The goal is not a guarantee of prevention, which no one can offer; it is meaningfully shifting the odds and, often, delaying onset — which at the population level would spare enormous suffering.

The evidence points to a coherent, mutually reinforcing set of actions. Protect your blood vessels: managing blood pressure, cholesterol, and diabetes, and not smoking, guards the brain's blood supply and is the shared core of preventing both vascular dementia and much of Alzheimer's^5,9. Stay physically active: exercise is among the best-supported protective behaviors, working through the biology detailed in our guide to exercise and brain health⁹. Eat for your brain and heart: a plant-forward, fish-rich dietary pattern is consistently associated with healthier brain aging, as discussed in our review of the MIND diet. Preserve your senses: treating hearing loss and vision loss is now on the list of modifiable factors⁹. Stay mentally and socially engaged: education, cognitively stimulating activity, and strong social connection build the buffer known as cognitive reserve, which helps the brain resist the effects of disease. And protect your sleep, whose links to long-term brain health are covered in our guide to sleep and cognitive decline.

None of these is a magic bullet, and the honest framing throughout this guide applies here too: these steps reduce risk rather than eliminate it, and they work best pursued together and sustained over years rather than adopted briefly and late. But taken as a whole, they amount to something genuinely hopeful — a large fraction of dementia risk is not written in stone, and the same handful of habits that protect the brain protect the heart and the body along with it. For a fuller, practical treatment, see our dedicated guides to reducing dementia risk and protecting your brain after 50.

§XIII.The bottom line

Dementia is frightening in large part because it is misunderstood, and clarity is its own kind of relief. It is not a single disease but a syndrome with many causes; not a normal part of aging but a consequence of specific brain diseases; and not the same as the ordinary forgetfulness that worries most people. It sits at the severe end of a spectrum that runs from normal change through mild cognitive impairment, and its major forms — Alzheimer's, vascular, Lewy body, frontotemporal, and often mixtures of these — each have their own biology and their own early signs. Its symptoms reach beyond memory into behavior and daily function, and its diagnosis is a careful process that can, importantly, catch treatable causes. Most hopeful of all, a substantial share of dementia risk is modifiable: the evidence now suggests that up to nearly half of cases could be prevented or delayed by addressing factors within reach. Understanding dementia will not make it less serious — but it can replace vague dread with accurate knowledge, earlier action, and a clear, evidence-based sense of what actually helps.

@misc{derbie_dementia_2026,
  author       = {Derbie, Abiot Y.},
  title        = {{Dementia and Cognitive Decline: Types, Symptoms, and Causes Explained}},
  year         = {2026},
  publisher    = {{LifeByLogic}},
  howpublished = {Online article},
  url          = {https://lifebylogic.com/learn/dementia-and-cognitive-decline/},
  note         = {Accessed: July 7, 2026}
}