A History of Alzheimer’s Disease
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia. The World Health Organization (WHO) estimates that 57 million people were living with dementia worldwide in 2021 - the figure it still cites in 2026 - with nearly 10 million new cases every year. Over 60% of those affected live in low and middle income countries. Alzheimer disease accounts for about 60 to 70% of dementia cases.
WHO and Alzheimer’s Disease International project that the number of people with dementia could reach 78 million by 2030 and 139 million by 2050 if no effective interventions change the course of the epidemic. Some Global Burden of Disease analyses put the 2050 figure higher, at around 153 million. The two projections use different methods but both point in the same direction which is a large and sustained increase within a relatively short time frame.
In the United Kingdom, research commissioned by Alzheimer’s Society and Alzheimer’s Research UK estimates that around 982,000 people are living with dementia. That total is projected to reach 1.4 million by 2040. Alzheimer’s disease accounts for approximately two thirds of cases. More than 70,800 people in the UK have young onset dementia, where symptoms begin before the age of 65. Alzheimer’s Society also estimates that one in three people born today will develop dementia in their lifetime.
Dementia Hub traces Alzheimer’s disease from its first identification in the early twentieth century to its present status as one of the world’s most urgent public health challenges. It covers clinical observation, scientific understanding, diagnosis, drug development, coping strategies for patients and carers, and the societal and economic impact of the condition in the United Kingdom and worldwide.
Our account draws on historical records, peer reviewed research and public data available up to September 2026. It is written for people living with Alzheimer’s, families and carers, researchers, clinicians, policymakers and the wider public.
What is Alzheimer's Disease
Alzheimer’s disease is a progressive brain condition that gradually affects memory, thinking and behaviour. It is the most common cause of dementia - a general term for a loss of cognitive abilities severe enough to interfere with everyday life. In simple terms, Alzheimer’s slowly damages and kills brain cells, making it harder to remember, decide, communicate or carry out familiar tasks.
At the heart of the disease are harmful changes inside the brain. Over time, abnormal sticky clumps of amyloid-beta (Aβ) protein - amyloid plaques - build up between brain cells, while twisted strands of a protein called tau form neurofibrillary tangles inside the cells. These plaques and tangles disrupt normal cell function: they block communication between neurons and help to trigger inflammation that harms cells further. Neurons begin to die and the connections between them break down.
The damage often begins in areas responsible for forming new memories, especially the hippocampus and entorhinal cortex. That is why short term memory loss is usually one of the first noticeable signs. As the disease spreads, it affects language, reasoning, planning and, later, basic functions such as movement or swallowing. Over years, large parts of the brain shrink. Severe confusion, personality change and loss of independence follow.
Plaques and tangles are the classic hallmarks of Alzheimer’s, but they are not the whole story. Many older people have mixed pathology, including vascular damage. Inflammation, problems with brain metabolism and the brain’s immune cells (microglia) also play important roles. That is why research has moved beyond amyloid alone.
The condition was first identified in 1906 by the German psychiatrist Alois Alzheimer, who examined the brain of a patient with unusual memory problems and found these distinctive plaques and tangles. During the early 20th century it was thought to be a rare condition but over time this was proven to be incorrect. Data from the Office for National Statistics show that dementia (including Alzheimer’s disease) remained the leading cause of death in England and Wales in 2025, with 72,272 deaths (12.7% of all deaths). The UK-wide figure for 2024 was 76,894 deaths. These figures refer to dementia recorded as the underlying cause of death - people dying from the condition, not simply with it.
The sections that follow examine how the disease received its name, how scientific understanding evolved, how diagnosis and treatment have changed, and what can already be done to reduce risk and support families.
Early Observations (Pre-1906)
Long before Alzheimer’s disease received its formal name, doctors noticed puzzling changes in older people’s minds and behaviour: gradual memory loss, confusion, personality shifts and difficulty with everyday thinking. These are the symptoms we now recognise as dementia, including what would later be identified as Alzheimer’s.
In the late eighteenth and early nineteenth centuries, French physicians such as Philippe Pinel, and later Jean Étienne Esquirol, helped turn “dementia” into a medical term rather than a moral judgement or a form of madness. They treated it as a brain-related condition that needed care and study. Around the same time, better methods for examining brain tissue after death allowed doctors to see physical changes in people who had shown these symptoms.
Prominent physicians began documenting older adults who were losing mental sharpness. Jean Martin Charcot, often called the “father of modern neurology”, observed memory weakening and slowed thinking in patients with various brain disorders and showed how damage to the brain could affect the mind.
Other doctors across Europe described “senile dementia” as more than normal ageing. In 1892, Paul Blocq and Gheorghe Marinescu reported “senile plaques” - sticky protein build ups in an older patient’s brain, though they did not yet link them to a distinct disease. The widespread view remained that forgetting names, withdrawing or acting oddly in old age was simply “part of getting older”. Families and doctors focused on basic care. Little effort went into causes or cures.
Without modern microscopes or brain scans, these reports were limited. Doctors could see behaviour in life and some shrinkage or hardening of the brain after death, but they lacked proof of the specific plaques and tangles that Alois Alzheimer would later describe.
Even so, nineteenth century observation shifted thinking from inevitable “old age weakness” towards the idea that something specific might be happening in the brain. That curiosity prepared the ground for Alzheimer’s landmark work in 1906 and 1907.
Identification (1900 - 1940)
The modern story of Alzheimer’s disease begins with Alois Alzheimer, a German psychiatrist and neuropathologist. In 1901, at a psychiatric hospital in Frankfurt, he met Auguste Deter, a 51 year old woman with severe memory problems, confusion, paranoia, hallucinations and difficulty recognising familiar people or objects. Her condition worsened rapidly. She died in 1906, aged 55.
After her death, Alzheimer examined her brain with the best staining methods then available. He found unusual sticky deposits outside brain cells (now called amyloid plaques) and twisted protein strands inside them (neurofibrillary tangles). On November 3rd 1906 he presented her case at a psychiatry conference in Tübingen as a “peculiar disease of the cerebral cortex” - the first public description of what we now recognise as Alzheimer pathology. In 1907 he published the findings, initially describing the condition as a form of “presenile dementia” because the patient was relatively young.
The presentation attracted little immediate attention. Many doctors still saw severe memory loss in younger adults as rare, and old age decline as inevitable.
The disease gained its name in 1910, when Emil Kraepelin, Alzheimer’s mentor, introduced “Alzheimer’s disease” in the eighth edition of his textbook Psychiatrie. He used it for cases starting before the age of 65, distinguishing them from “senile dementia” in older people. The distinction was debated from the start, because similar brain changes appeared in both younger and older patients. Kraepelin’s naming nonetheless marked the condition as a specific illness worthy of study.
In the same year as Alzheimer’s 1907 paper, Oskar Fischer in Prague described neuritic plaques in detail across 12 older patients with dementia. He later suggested that plaques might link “presenile” and “senile” forms, challenging Kraepelin’s strict age split. Fischer’s work complemented Alzheimer’s but received less recognition, in part because of rivalries between research schools and later historical events.
Progress slowed in the 1920s and 1930s. Diagnosis still depended on autopsy and basic microscopy. The Great Depression cut research funding. When brains were examined, plaques and tangles were found repeatedly, but explanations varied: hardened arteries, normal ageing, even hormone imbalance. Alzheimer’s disease remained a niche interest for neuropathologists rather than everyday doctors.
All the same, the period 1900s to the 1940s turned vague ideas of “senile decay” into a recognisable brain disease with specific hallmarks.
Understanding (1940s - 1960s)
After the Second World War, as people lived longer, dementia became harder to ignore. In the 1940s and early 1950s many doctors still blamed severe memory loss in older people on hardened arteries reducing blood flow (cerebral arteriosclerosis), or on ageing itself. Alzheimer’s was still viewed as a rare disease of younger adults, not the common “senile dementia” of later life.
New tools changed that view with electron microscopes, widely available by the 1950s, allowing scientists to see brain tissue in far greater detail. During the early 1960s, researchers including Robert Terry and Martin Kidd described the fine structure of amyloid plaques and neurofibrillary tangles and confirmed that these were key features of the disease, not random ageing changes.
Population studies showed how common dementia really was. Work in Newcastle upon Tyne in the late 1950s and early 1960s, associated with Martin Roth and colleagues, found that a substantial minority of people over 65 had significant dementia, often linked to high numbers of plaques and tangles rather than artery disease alone.
The turning point came with British researchers Gary Blessed, Bernard Tomlinson and Martin Roth. Their influential 1968 study linked the amount of plaque in the brain with how severe a person’s dementia had been in life. People with many plaques scored poorly on memory and thinking tests shortly before death; those with few plaques stayed sharper. This helped convince the medical world that most “senile dementia” in older people was the same disease Alzheimer had described, not a separate condition or normal ageing.
Later in the 60s and into the 70s, scientists found that Alzheimer’s brains had much lower levels of acetylcholine, a chemical messenger vital for memory and learning. That observation produced the “cholinergic hypothesis”: boosting acetylcholine might ease symptoms. It opened the door to the first generation of Alzheimer’s medicines.
By the end of this period, Alzheimer’s had moved from a forgotten rarity to a specific disease that could be studied scientifically.
Research Advances (1970s-1980s)
The 1970s and 1980s turned Alzheimer’s from an “old-age problem” into a major research field. Scientists developed shared diagnostic rules, new ways to look at the living brain, and early clues about chemicals and genes.
Follow up of the British clinicopathological studies showed that Alzheimer pathology caused a large share of late-life dementia - often half or more of cases in older people - rather than a rare presenile curiosity.
In 1984, a working group from the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) and the Alzheimer’s Disease and Related Disorders Association (ADRDA) published diagnostic guidelines that gave researchers a common language. The criteria focused on gradual memory loss, difficulty with daily tasks and the exclusion of other causes, with definite confirmation still depending on brain examination. Those clinical rules have since been updated, but they made international comparison possible.
Imaging arrived. CT scans in the 1970s showed the brain shrinkage typical of Alzheimer’s. In the 1980s, PET scans revealed reduced glucose use in memory and thinking regions while people were still alive.
The cholinergic hypothesis matured. Loss of acetylcholine-producing cells in the basal forebrain was linked to much of the cognitive impairment. Early experiments with cholinesterase inhibitors - drugs that slow the breakdown of acetylcholine - laid the groundwork for the first licensed treatments in the 1990s.
Deeper studies in genetics also began during this period and in 1987, teams identified mutations in the amyloid precursor protein (APP) gene on chromosome 21 in rare early onset families. That finding tied a gene directly to amyloid plaques and supported the emerging idea that abnormal amyloid processing can start the disease.
Advocacy grew with the founding of the Alzheimer’s Association in the United States in 1980 and expanding campaigns in the UK and elsewhere. Funding and collaboration increased. No cure emerged, but the tools of modern Alzheimer research - criteria, imaging, chemistry and genes - were now in place.
Genetic Breakthroughs (1990s)
The 1990's revealed why some people develop Alzheimer’s earlier or more severely than others, strengthened a leading theory of how the disease starts, and produced the first medicines aimed at symptoms.
Early onset familial Alzheimer’s, which often begins before 65 and runs strongly in families, is uncommon typically about 1 to 5% of cases, but it provided decisive clues. Building on the 1987 APP discovery, scientists in 1995 identified mutations in presenilin 1 (PSEN1) on chromosome 14 and presenilin 2 (PSEN2) on chromosome 1. PSEN1 mutations account for most autosomal dominant familial cases; PSEN2 is rarer and often associated with a slightly later onset. Presenilin proteins form part of γ-secretase, the enzyme that cuts APP to release amyloid beta. Mutations push production towards the stickier Aβ42 form that seeds plaques.
In 1993, researchers showed that a common variant of the apolipoprotein E gene, APOE ε4, raises risk for the much more common late onset disease that begins after 65. APOE helps transport cholesterol and fats. The ε4 version is linked to poorer clearance of amyloid-beta and greater plaque build up. One copy is often quoted as raising risks up to a factor of three; two copies raise it substantially more and tends to bring symptoms earlier. Exact figures vary by ancestry, so ε4 should be described as a risk factor, not a cause. Unlike APP or presenilin mutations, it does not make the disease inevitable. Roughly 15 to 25% of people carry at least one ε4 allele, depending on population.
These discoveries supported the amyloid cascade hypothesis, proposed in 1992 by John Hardy and Gerald Higgins: excess Aβ starts a chain of plaques, inflammation, tau tangles, cell death and clinical dementia. The hypothesis guided a generation of drug development and still remains influential, but it is no longer treated as the only pathway. Tau, inflammation, vascular disease and immune function are now pursued in parallel research.
Treatment advanced too. In 1993 the US FDA approved tacrine, the first cholinesterase inhibitor for Alzheimer’s. It offered modest help with thinking and daily function for some people with mild to moderate disease, but liver toxicity limited its use and it was later withdrawn. Donepezil, approved in 1996, was easier to take and better tolerated. These drugs do not stop the disease. They showed that targeting brain chemistry can ease symptoms and encouraged larger trials.
By 2000, Alzheimer’s was no longer a mysterious fate of old age. It was a genetic and biological puzzle that could be measured, monitored and more importantly attacked in the laboratory and the clinic.
Therapeutic Developments and Global Awareness (2000s)
The 2000s provided an all important decade of growing public recognition, larger trials and hard lessons. Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and the NMDA receptor antagonist memantine became standard symptomatic treatments in many countries, including the UK. They remain useful for some people, particularly in mild to moderate disease, but they do not alter the underlying course.
Researchers launched ambitious anti amyloid programmes - vaccines, antibodies and secretase inhibitors. Several high profile trials failed or were stopped because of side effects or lack of clear clinical benefit. Those failures did not disprove the importance of amyloid; they showed that timing, the form of amyloid targeted, and safety all matter. They also pushed the field to develop better ways of confirming Alzheimer pathology in living people.
Diagnosis improved. MRI became routine for assessing atrophy and ruling out other causes. Research PET ligands began to show amyloid in the living brain, although clinical use was still limited. Cerebrospinal fluid tests for amyloid beta and tau entered specialist practice.
Public health caught up with the science. Ageing populations made dementia impossible to treat as a private family misfortune. Charities in the UK - notably Alzheimer’s Society and Alzheimer’s Research UK - expanded research funding, campaigning and support services. Similar organisations grew worldwide. Governments began to talk about national dementia strategies. The idea that “dementia is not an inevitable part of ageing” entered mainstream health policy, even if services often lagged behind the rhetoric.
By 2010 the field had symptomatic drugs, a clearer biological model, better imaging, and a public that expected more than comfort care. What it did not yet have was a treatment that slowed the disease itself.
Modern Era: Research and Policy (2010s-2025)
From 2010 to the current day, research has moved from describing Alzheimer pathology to detecting it earlier and, for the first time, modestly slowing decline in some people with early disease. Policy and funding has increased, though access to new drugs in the NHS remains limited.
How common it is now?
Most cases (over 95%) occur in people aged 65 and older. Risk rises sharply with age; prevalence roughly doubles every five years in later life. Women account for about two thirds of those living with dementia, largely because they live longer, though sex differences in biology and unpaid care also matter.
In England as of 2026, the estimated diagnosis rate for people aged 65 and over was about 66% meaning roughly one in three older people with dementia still has no recorded diagnosis. Alzheimer’s Society reports that people wait an average of 3.5 years from first symptoms to diagnosis, including months after GP referral to a memory clinic. Diagnosis rates are lower in parts of Wales and in many lower income countries. Ethnic minority and deprived communities often face extra barriers.
Diagnosis: from symptoms to biology
Amyloid PET scans (florbetapir was approved in the US in 2012) allowed doctors to see plaques in living brains with Tau PET scans following. The most practical change for clinics has been blood tests, especially those measuring phosphorylated tau (p-tau217 and related markers) alongside amyloid measures. In research settings these tests often reach 85 to 95% accuracy and are far less invasive than lumbar puncture or PET. In the UK, programmes such as the Blood Biomarker Challenge have been testing how to use them in NHS memory services.
Expert guidelines in the mid 2020s increasingly define Alzheimer’s as a biological process that can be detected by biomarkers before dementia is obvious. That shift matters for trials and, eventually, for offering treatment earlier. It does not mean everyone with a positive blood test should be labelled with dementia; clinical judgement remains essential.
Genetics beyond APOE
Large genome wide studies have identified many additional risk loci. Polygenic risk scores combine those signals to estimate likelihood more finely than APOE alone. They are used in research and trial selection more than in routine NHS care. Laboratory work with gene-editing tools such as CRISPR has explored genes including APOE, but this remains experimental.
The first disease modifying drugs
Anti amyloid monoclonal antibodies were the first treatments shown to change the disease process rather than symptoms alone.
- Lecanemab (Leqembi) was licensed by the UK Medicines and Healthcare products Regulatory Agency (MHRA) in August 2024. In the Clarity AD trial it slowed clinical decline by about 27% over 18 months in people with early Alzheimer’s confirmed by biomarkers.
- Donanemab (Kisunla) was licensed by the MHRA in October 2024. In TRAILBLAZER-ALZ 2 it slowed decline by around 35% in some analyses. Treatment can be stopped once plaques are cleared on scanning.
Both work best in early disease (mild cognitive impairment or mild dementia due to Alzheimer’s). Both require infusions or specialist delivery and regular MRI scans because of ARIA - amyloid related imaging abnormalities, including brain swelling and small bleeds. Risk is higher for people with two copies of APOE ε4.
Licensing is not the same as NHS funding. NICE concluded that the average benefit was too small to justify the cost of the drugs, infusions and monitoring, and has not recommended either medicine for routine NHS use. Appeals in 2026 led to further committee review and commercial talks between NHS England and the manufacturers. As of September 2026 there is still no routine NHS rollout. Private or trial access may exist for a small number of people. The distinction between licensing and funding should always be stated clearly to families.
The Pipeline
Amyloid is no longer the only target. By 2026 the clinical pipeline included agents against tau, inflammation, microglial function (including TREM2), metabolism and neuroprotection, as well as repurposed drugs such as GLP-1 receptor agonists used in diabetes.
Two programmes attracted particular attention in 2026:
- Trontinemab, Roche’s “brain shuttle” anti amyloid antibody, designed to cross the blood brain barrier more efficiently. Phase 2 work showed rapid plaque clearance and relatively low reported ARIA. Phase 3 trials in early symptomatic Alzheimer’s are under way, with results not expected before 2028. A prevention trial in cognitively unimpaired people with raised plasma p-tau217 has been announced.
- Diranersen (BIIB080), a tau targeting antisense oligonucleotide given by lumbar injection. Phase 2 CELIA data in 2026 showed substantial reductions in tau biomarkers and signals of slower decline on several cognitive measures, prompting plans for Phase 3.
A full cure remains elusive. Combination treatment — amyloid plus tau, or drug plus lifestyle — is the direction many researchers expect.
Policy and funding
WHO’s Global Action Plan on the Public Health Response to Dementia (2017–2025) was extended to 2031 in May 2025. By 2026 about 47 countries had a national dementia plan, however this is still only around a quarter of World governments. Alzheimer’s Disease International continues to press for faster implementation.
In the UK, the Dame Barbara Windsor Dementia Mission (launched in 2022) has aimed to speed diagnostics, trials and innovation, including blood tests and a trials accelerator. Government research funding increased during the mid 2020s, while Alzheimer’s Research UK and Alzheimer’s Society remain major charitable funders. NHS policy has emphasised diagnosis and support, though the formal national diagnosis rate target has been revised in recent planning guidance and services still vary widely by area.
Prevention policy has sharpened with the 2024 Lancet Commission concluding that tackling 14 modifiable risk factors across the life course could theoretically prevent or delay around 45% of dementia cases. WHO’s updated 2026 risk reduction guidelines take a similar line and stress lifestyle and long term condition management rather than routine vitamin or omega3 supplements in people without a diagnosed deficiency.
The 14 factors are: less education in early life; hearing loss; high blood pressure; smoking; obesity; depression; physical inactivity; diabetes; excessive alcohol; traumatic brain injury; air pollution; social isolation; high LDL cholesterol; and untreated vision loss. Hearing loss and high LDL each account for a large share of the population-level risk.
Societal Impact and Future Directions
Alzheimer’s disease and other dementias reshape families, health systems and economies. Longer lives mean more people reach the ages of highest risk with the result being pressure on the NHS, social care and unpaid family life - and a growing case for prevention and earlier support.
Economic cost
In the UK, dementia cost the economy around £42 billion in 2024, covering health care, social care and the value of unpaid care. That total is projected to rise to about £90 billion by 2040. More than half of the burden often falls on unpaid carers, usually partners or adult children who reduce hours or leave work. Families also pay directly for private care.
Globally, dementia was estimated to cost US$1.3 trillion in 2019, with informal care about half of that. Costs could reach US$2.8 trillion by 2030. In lower and middle income countries, where most future cases will occur, families carry even more of the load because formal services are scarce.
Families and carers
Care often means daily help with washing, eating, medicines, safety and companionship. Carers face exhaustion, anxiety, depression and their own health problems. Many describe grieving the person they knew while still providing care. In a 2026 Alzheimer’s Society survey, 43% of carers said they had reached breaking point; 56% said caring had damaged their mental health. Women provide most unpaid care hours worldwide (around 70% in WHO estimates) and face a “triple burden”: higher likelihood of developing dementia, more years lived with disability, and more time spent caring.
Young onset dementia brings extra strain — jobs, mortgages, school age children all bring a combination of stress, tiredness, forgetfulness and many other symptoms that are brushed off or ignored - and due to lack of general awareness it is easily missed because it is not the type of illness many would expect under the age of 65.
Diagnosis still comes too late
England’s diagnosis rate near 66% is better than many countries but still leaves hundreds of thousands without formal support, planning or treatment. The 3.5 year wait from first symptoms is long enough for people to lose driving, work or the chance to take part in trials. Under diagnosis is far worse in many lower income settings.
A diagnosis is not only a label. Most people affected say it helps them get the right care. It also opens the door to legal planning (including lasting powers of attorney), financial benefits, and support from charities.
What can be done now
Waiting for a perfect drug is not a strategy. Evidence based steps already matter.
Reduce risk across life
- Treat hearing loss; use hearing aids if needed.
- Check and treat midlife blood pressure, LDL cholesterol, diabetes and obesity.
- Stop smoking; keep alcohol within UK low-risk guidelines.
- Stay physically active; protect the head in cycling and contact sport.
- Keep socially connected; treat depression.
- Have regular eye tests and correct vision problems.
- Value education and later life learning — cognitive reserve does not prevent pathology, but it can delay its impact.
These actions do not guarantee that any one person will avoid dementia, including people with high genetic risk. They are still the strongest population level tools available in 2026.
After symptoms appear
- See a GP early. Memory assessment services can look for reversible causes as well as dementia.
- Ask about cholinesterase inhibitors or memantine where appropriate.
- Ask whether biomarker tests (including emerging blood tests) are relevant.
- Do not assume lecanemab or donanemab will be available on the NHS; check current NICE and local guidance.
- Seek a carer’s assessment and advice on Attendance Allowance, Carer’s Allowance and local respite.
- Contact Alzheimer’s Society on 0333 150 3456, or Alzheimer’s Research UK and Dementia UK for information and Admiral Nurse support.
Looking ahead
Priorities for the next decade are clear: cheaper accurate blood tests in everyday clinics; fairer diagnosis; treatments that are safer, more effective and affordable enough for the NHS; combination approaches that go beyond amyloid; and serious investment in carers and social care. Rehabilitation - helping people live as well as possible with the diagnosis - is receiving overdue attention, including in Alzheimer’s Disease International’s World Alzheimer Report 2025.
The scale of Alzheimer’s disease is daunting. So is the progress since Auguste Deter’s case was presented in 1906. The disease can now be seen in life, explained in molecular terms, slowed modestly in some people, and delayed for many others by changes that start in midlife or earlier. That is not a cure. It is a foundation. Used well in clinics, homes and public policy it can reduce the number of people who reach severe dementia and ease the load on the families who walk the path with them.
Factcheck 06/09/2026
Grok (X): Reviewed 6 September 2026 against WHO, ONS and UK charity sources; key statistics, history and NHS treatment status are accurate.
Google AI: This article is highly accurate, providing up-to-date 2026 data on global dementia prevalence, UK mortality statistics, blood biomarkers, and the current NHS funding status of disease-modifying drugs like lecanemab.
Dementia Hub: This page has been verified accurate via the above AI engines, we recommend consulting a fully trained health official before making any changes to your diet, medication or routine.
