Alzheimer’s disease
A brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest tasks. It is the most common cause of dementia among older adults — and the brain changes behind it begin long before anyone notices a symptom.
6 million+
Americans may have Alzheimer’s — most of them age 65 or older. Estimates vary.
National Institute on Aging7th
Alzheimer’s is currently ranked the seventh leading cause of death in the United States.
National Institute on AgingMost common
It is the most common cause of dementia among older adults — but it is not the only one.
National Institute on AgingIn most people with Alzheimer’s, symptoms first appear later in life. Dementia itself is the loss of cognitive functioning — thinking, remembering and reasoning — and of behavioural abilities, to an extent that interferes with daily life. It ranges from the mildest stage, when it is only just beginning to affect how someone functions, to the most severe, when a person depends completely on others for basic daily activities. The Dementia tab sets out the other types: Lewy body dementia, frontotemporal disorders, vascular dementia, and mixed dementia — which is common, and often means Alzheimer’s and vascular changes in the same person.
The sentence this platform exists because of
“Changes in the brain may begin a decade or more before symptoms appear.”
During that very early stage, toxic changes are already taking place: abnormal buildups of proteins forming amyloid plaques and tau tangles. Previously healthy neurons stop functioning, lose their connections to other neurons, and die. The damage appears to begin in the hippocampus and the entorhinal cortex — the parts of the brain essential to forming memories. As more neurons die, other regions are affected and begin to shrink. By the final stage, the damage is widespread and brain tissue has shrunk significantly.
National Institute on Aging — Alzheimer’s Disease Fact SheetA decade is not a detail. It is the reason a dated record kept over years is worth more than any single score, and the reason this platform asks the same questions every quarter instead of once at a crisis. If the biology moves for ten years before anyone notices, then the only thing that can catch it is comparison against the same person earlier.
It is also why the cognitive instrument used here, the IQCODE, asks about change against ten years ago rather than testing what someone can recall today. Not “can they do it” but “has it changed” — which is the question the decade makes the important one.
What this does not mean. Nothing here detects amyloid or tau. Those need a PET scan, a spinal tap or a blood test ordered by a clinician. A questionnaire cannot see protein in a brain, and this platform never suggests otherwise.
Alzheimer’s disease is named after Dr. Alois Alzheimer. In 1906 he noticed changes in the brain tissue of a woman who had died of an unusual mental illness; her symptoms had included memory loss, language problems and unpredictable behaviour. Examining her brain, he found many abnormal clumps — now called amyloid plaques — and tangled bundles of fibres, now called neurofibrillary, or tau, tangles.
Those plaques and tangles are still considered among the main features of the disease. So is a third: the loss of connections between neurons. Neurons carry messages between parts of the brain, and from the brain to the muscles and organs of the body.
Memory problems are typically one of the first signs of cognitive impairment related to Alzheimer’s. Some people with memory problems have mild cognitive impairment (MCI): more memory problems than is normal for their age, but symptoms that do not interfere with their everyday lives. Movement difficulties and problems with the sense of smell have also been linked to MCI.
Older people with MCI are at greater risk of developing Alzheimer’s — but not all of them do. Some may even revert to normal cognition.
Which is exactly why a reading here is a record and not a verdict. A single sitting cannot tell you which of those paths someone is on. A run of sittings can at least show which way things are moving — including the direction nobody expects, which is back toward normal.
The first symptoms vary from person to person, and they are not always about memory. For many people the earliest sign is a decline in something else: word finding, vision and spatial problems, or impaired reasoning or judgement.
Researchers are studying biomarkers — biological signs of disease found in brain images, cerebrospinal fluid and blood — to detect early changes in people with MCI and in cognitively normal people who may be at greater risk. More research is needed before these techniques can be used broadly and routinely to diagnose Alzheimer’s in a health care provider’s office.
Greater memory loss and other cognitive difficulties. Problems can include wandering and getting lost, trouble handling money and paying bills, repeating questions, taking longer to complete normal daily tasks, and personality and behaviour changes.
People are often diagnosed at this stage.
Damage occurs in areas of the brain controlling language, reasoning, conscious thought and sensory processing — including the ability to correctly detect sounds and smells. Memory loss and confusion grow worse, and people begin to have problems recognising family and friends.
They may be unable to learn new things, carry out multistep tasks such as getting dressed, or cope with new situations. People at this stage may also have hallucinations, delusions and paranoia, and may behave impulsively.
Plaques and tangles spread throughout the brain and brain tissue shrinks significantly. People with severe Alzheimer’s cannot communicate and are completely dependent on others for their care.
Near the end of life, the person may be in bed most or all of the time as the body shuts down.
Scientists have made tremendous progress, and still do not yet fully understand what causes Alzheimer’s disease in most people. The causes probably include a combination of age-related changes in the brain along with genetic, environmental and lifestyle factors — and how much any one of them matters may differ from person to person.
One of the great mysteries is why it largely affects older adults. Research on normal brain ageing is exploring how age-related changes may harm neurons and affect other brain cells: atrophy of certain parts of the brain, inflammation, blood vessel damage, production of unstable molecules called free radicals, and mitochondrial dysfunction — a breakdown of energy production inside a cell.
In most cases Alzheimer’s does not have a single genetic cause. It is likely influenced by multiple genes together with lifestyle and environmental factors, and genetic variations may increase or decrease a person’s risk.
More than 80
Scientists currently know of more than 80 genetic regions associated with Alzheimer’s. Association is not causation, and almost none of them cause it.
Only three cause it
Rarely, someone inherits an altered version of one of these three. They will likely develop Alzheimer’s before age 65, and sometimes much earlier.
Risk, not destiny
APOE ε4 increases risk and is associated with developing Alzheimer’s earlier in life for certain populations. APOE ε2 may provide some protection.
Chromosome 21
An extra chromosome 21 carries the APP gene, and too much of that protein leads to beta-amyloid buildup. Estimates suggest 50% or more of people living with Down syndrome will develop Alzheimer’s, with symptoms appearing in their 50s and 60s.
And still: it is never known for certain whether any individual will or will not develop the disease.
Research suggests a host of factors beyond genetics play a role. There is a great deal of interest in the relationship between cognitive decline and vascular conditions — heart disease, stroke, high blood pressure — and metabolic diseases such as diabetes and obesity. Ongoing research will help establish whether and how reducing those risk factors also reduces the risk of Alzheimer’s.
A nutritious diet, physical activity, social engagement and mentally stimulating pursuits have all been associated with staying healthy while ageing, and might also help reduce the risk of cognitive decline and Alzheimer’s. Researchers are testing some of these possibilities in clinical trials. What You Can Do to Help goes through the evidence on each one, including where it stops short.
Doctors use several methods and tools together. No single one of them settles it.
These tests may be repeated, to show how a person’s memory and other cognitive functions are changing over time.
Step 1 is ask the person and someone close to them, including about the ability to carry out daily activities. Step 4 is check whether depression or another mental health condition is causing or contributing to the symptoms. Those two steps are the shape of a sitting on this platform: two instruments answered by the person, two by an informant, and the mental-health questions asked first rather than as an afterthought.
That is not a claim to do a clinician’s work. Steps 2, 3, 5 and 6 need a clinic, a lab and a scanner, and nothing here substitutes for any of them. What a sitting can do is arrive at the appointment with steps 1 and 4 already written down, dated, and repeated over quarters — instead of being reconstructed from memory in fifteen minutes.
Symptoms can have other causes, and some of them can be treated. People with memory and thinking concerns should talk to a doctor about whether their symptoms are due to Alzheimer’s or to something else: stroke, a tumour, Parkinson’s disease, sleep disturbances, side effects of medication, an infection, or another type of dementia. Some of these conditions may be treatable and, possibly, reversible.
Beginning treatment as early as possible in the disease process may help preserve daily functioning for a while. An early diagnosis also lets families plan: financial and legal matters, potential safety issues, living arrangements, and building a support network. And it opens more opportunities to take part in clinical trials or studies of possible new treatments.
Alzheimer’s is complex, and it is therefore unlikely that any one drug or other intervention will successfully treat it in all people living with the disease. Scientists are developing and testing several possible interventions in ongoing clinical trials.
There is currently no cure. Medications are emerging to treat the progression of the disease by targeting its underlying causes, and there are also medications that may temporarily improve or stabilise memory and thinking skills in some people, and that may help manage certain symptoms and behavioural problems.
People with Alzheimer’s may also experience sleeplessness, depression, anxiety, agitation and other behavioural and psychological symptoms. Research shows that treating these can make people more comfortable and also help their caregivers.
Caring for a person with Alzheimer’s can carry significant physical, emotional and financial costs. The demands of day-to-day care, changes in family roles, and decisions about placement in a care facility can all be difficult.
Becoming well-informed about the disease is one important long-term strategy. Programmes that teach families about the stages and about ways to deal with difficult behaviours and other caregiving challenges can help. So can good coping skills, a strong support network, and respite care — and staying physically active brings both physical and emotional benefits.
Some caregivers have found that joining a support group is a critical lifeline: a place to find respite, express concerns, share experiences, get tips and receive emotional comfort. Many organisations sponsor in-person and online groups, including groups for people with early-stage Alzheimer’s and their families.
Everybody may be able to take part: people with Alzheimer’s or mild cognitive impairment, and healthy volunteers with or without a family history. Participants help scientists learn how the brain changes both in healthy ageing and in Alzheimer’s.
Many volunteers are needed for the hundreds of active trials and studies testing ways to better understand, diagnose, treat and prevent the disease. Researchers need participants of different ages, sexes, races and ethnicities so that results are meaningful for many people — a point worth holding onto, since the narrowness of validation samples is a limit stated plainly on our own evidence page.
The NIA leads the federal government’s research effort. NIA-funded Alzheimer’s Disease Research Centers across the United States study the causes, diagnosis and management of the disease, and the NIA also sponsors the Alzheimer’s Clinical Trials Consortium.
Ways in: talk to your health care provider about local studies; search the Alzheimers.gov Clinical Trials Finder; sign up for a registry or matching service; or contact an Alzheimer’s Disease Research Center, or a memory or neurology clinic in your community.
Not a diagnosis — that needs a clinician, an examination and usually tests. What a dated run of sittings can do is carry the two steps a questionnaire can do — asking the person and someone close to them, and checking whether mood is part of the picture — into the appointment already written down. And because the brain changes begin a decade or more before symptoms, the comparison against this person’s own earlier answers is the only instrument any of us has that works on that timescale.
If you are worried about someone right now, that is a reason to call their clinician rather than to wait for a quarterly review. In crisis, call or text 988 (Suicide & Crisis Lifeline). The Alzheimer’s Association Helpline is 800.272.3900, 24 hours a day.