Dementia and Alzheimer's disease

Dementia is not a single disease. It is a general term for a loss of memory, thinking, and reasoning severe enough to interfere with daily life, and it has several distinct causes. Alzheimer's disease is the most common, but vascular dementia, Lewy body dementia, and frontotemporal dementia each look and behave somewhat differently. Knowing which one is involved shapes what to expect and what treatments make sense.

Dementia becomes more common with age, though it is not a normal part of aging. An estimated 7.4 million Americans age 65 and older are living with Alzheimer's in 2026, which is about 1 in 9 people in that age group; the number is projected to grow to 13.8 million by 2060 as the population ages ¹. Most people with dementia are cared for at home by family, which makes this as much a caregiving topic as a medical one.

The last few years have brought real change: the first drugs shown to slow Alzheimer's, a blood test that can support diagnosis, and stronger evidence that a meaningful share of dementia is tied to risk factors people can act on. None of this amounts to a cure. What follows tries to state honestly what is known, what the treatments do and do not do, and where to get help.

The main types of dementia#

Alzheimer's disease accounts for the majority of dementia in older adults. It is linked to abnormal buildups of two proteins in the brain, amyloid plaques and tau tangles, and it usually begins with trouble remembering recent events before spreading to language, judgment, and daily function ².

The other common types have their own signatures. Vascular dementia results from strokes or damaged blood vessels that cut blood flow to parts of the brain; it can appear in a stepwise pattern after strokes. Lewy body dementia involves deposits of a protein called alpha-synuclein and often brings visual hallucinations, movement problems resembling Parkinson's disease, and marked swings in alertness. Frontotemporal dementia tends to strike earlier, sometimes before 60, and often changes personality, behavior, or language more than memory at first ². Many older adults have mixed dementia, with more than one of these processes present at once.

Sources for this section: [2]

Normal aging versus warning signs#

Some forgetfulness is ordinary. Occasionally misplacing keys, blanking on a name and recalling it later, or walking into a room and forgetting why are common at any age. Warning signs are more disruptive and tend to worsen.

The Alzheimer's Association describes concrete examples worth attention: memory loss that disrupts daily life, such as asking the same question repeatedly or leaning heavily on notes for things once handled from memory; trouble following a familiar recipe or paying bills; getting lost driving to a familiar place; losing track of dates or the season; putting things in odd places and being unable to retrace steps; and withdrawing from work or social activities ³. A single lapse is not the concern. A pattern of change from a person's own baseline is.

Some causes of memory trouble are treatable and reversible, including thyroid problems, vitamin B12 deficiency, medication side effects, depression, sleep disorders, and infections. That is one reason a proper evaluation matters rather than assuming the worst.

Sources for this section: [3]

How dementia is diagnosed now#

Diagnosis still rests on a careful history and cognitive testing. A clinician asks about the timeline, tests memory and thinking with standard tools, reviews medications, and orders blood work to rule out reversible causes. A brain scan (CT or MRI) checks for strokes, bleeding, or other findings ².

What has changed is the ability to detect the biology of Alzheimer's. Amyloid can be confirmed with a PET scan or a spinal fluid test, and as of May 2025 the FDA cleared the first blood test to help diagnose Alzheimer's: the Lumipulse test measures a ratio of proteins (pTau217 and beta-amyloid) that tracks with brain amyloid ⁴. It is meant for people 55 and older who already have memory symptoms, and it is being introduced first in specialty and memory-clinic settings rather than as a routine screen for people without symptoms. A blood test is easier than a spinal tap or PET scan, but a positive result supports rather than replaces a full evaluation, and amyloid can be present without dementia.

The blood-test picture kept moving after that. In October 2025 the FDA cleared a second test, Roche's Elecsys pTau181, as the first one meant for use in primary care rather than only memory clinics. It is designed to help rule out Alzheimer's-related amyloid in people 55 and older who have cognitive symptoms: a negative result makes amyloid buildup unlikely and can spare some patients a PET scan or spinal tap, while an abnormal result points toward further specialist testing ⁹.

Sources for this section: [2] [4] [9]

What the anti-amyloid drugs do and do not do#

Two infused antibodies, lecanemab (brand name Leqembi) and donanemab (Kisunla), are the first treatments shown to slow Alzheimer's rather than only ease symptoms. Both clear amyloid plaque from the brain, and both are approved only for early Alzheimer's, meaning mild cognitive impairment or mild dementia with confirmed amyloid. They are not for moderate or advanced disease, and they do not stop or reverse the illness.

The benefit is a modest slowing of decline. In its main trial, lecanemab slowed decline on an 18-point clinical scale by about 27 percent over 18 months, an absolute difference of less than half a point ⁵. Donanemab slowed decline by about 35 percent on a different scale in the group with lower levels of tau ⁶. In practical terms, that can mean holding on to abilities somewhat longer, not restoring lost ones. Reasonable people weigh that differently.

The main risk is a set of side effects called ARIA (amyloid-related imaging abnormalities): temporary brain swelling or small brain bleeds seen on MRI. Most cases cause no symptoms, but a minority are serious, and rare deaths have occurred. Brain swelling appeared in about 13 percent of people on lecanemab and about 24 percent on donanemab in trials, though a revised donanemab dosing schedule approved in 2025 lowered that rate ⁵⁶. Risk is higher for people who carry two copies of a gene called APOE4, so genetic testing is part of the decision, and treatment requires periodic MRI monitoring. People on blood thinners face added bleeding risk.

Lecanemab now also comes in an at-home form. The FDA approved Leqembi Iqlik, a subcutaneous version given as a weekly injection through an autoinjector instead of an IV infusion; with a 2026 clearance for the starting dose added to an earlier clearance for maintenance, it became the first anti-amyloid treatment that can be given at home across the full course of therapy ¹⁰. The safety warnings and MRI monitoring still apply, since it delivers the same drug.

Cost and access are real considerations. Lecanemab's list price is about $26,500 a year before infusion, scanning, and monitoring costs ⁵. Medicare Part B covers these drugs when the prescriber takes part in a data registry, and beneficiaries generally owe the standard 20 percent coinsurance unless they have supplemental coverage.

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Symptom-based treatments#

Older drugs do not change the disease but can ease symptoms. Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) are used for mild to moderate Alzheimer's and may modestly help memory and thinking for a time. Memantine is used for moderate to severe disease and works on a different brain chemical; the two are sometimes combined ⁷. Treating mood, sleep, and behavioral symptoms matters as much, and non-drug approaches (routine, activity, a calm environment) are the first line for agitation. Good sleep and aging habits and attention to mental health in older adults both affect how someone with dementia functions day to day.

Sources for this section: [7]

Reducing risk: the 2024 Lancet Commission#

In 2024, the Lancet Commission on dementia concluded that about 45 percent of dementia cases worldwide are potentially preventable by addressing 14 modifiable risk factors across life ⁸. The factors are: less education in early life; hearing loss; high LDL cholesterol; depression; head injury; physical inactivity; diabetes; smoking; high blood pressure; obesity; excessive alcohol; social isolation; air pollution; and untreated vision loss. Hearing loss and high LDL cholesterol were each estimated to account for about 7 percent of cases, among the largest single contributions ⁸.

This is a population estimate, not a promise for any individual, and much of the risk is set earlier in life. Still, several factors remain worth acting on later: treating hearing loss and vision and eye health problems, controlling blood pressure and cholesterol, staying physically active as covered in exercise for seniors, eating well as in nutrition for seniors, and keeping up social ties discussed in staying socially connected. Managing these also lowers stroke and heart risk, so the effort pays off regardless.

The clearest evidence that acting on these factors helps comes from a trial rather than a population estimate. The US POINTER study, published in 2025, randomly assigned 2,111 adults aged 60 to 79 who were at risk of decline to either a structured program or a self-guided one, both built around regular exercise, the MIND diet, cognitive and social activity, and monitoring of blood pressure and other heart-health numbers. After two years, both groups improved on tests of thinking, and the structured group improved somewhat more. It was the first large US trial to show that a lifestyle program can protect cognition in a diverse older population, and the benefit held regardless of sex, genetic risk, or heart health at the start ¹¹.

Sources for this section: [8] [11]

Living after a diagnosis#

An early diagnosis, while hard to receive, allows time to plan while a person can still take part. That includes putting legal and financial documents in order through power of attorney and advance directives, simplifying finances, and guarding against fraud, since cognitive decline raises vulnerability to the schemes covered in elder abuse. Home safety and fall prevention reduce accidents as the disease progresses. Many people live meaningfully for years after diagnosis, especially in the early stage.

As dementia advances, care needs grow, and families often draw on adult day programs, in-home help, and eventually residential care or the comfort-focused approach in hospice and palliative care. Long-distance families face particular challenges covered in long-distance caregiving.

Caregiver resources#

Caring for someone with dementia is demanding, and caregivers who protect their own health provide better care. Respite, support groups, and clear information all help, and the broader picture is in family caregiving.

Medicare also runs a dementia-specific care program that many families have never heard of. Under the GUIDE Model (Guiding an Improved Dementia Experience), a person with dementia who has Original Medicare and lives at home can enroll with a participating provider and get a care navigator, 24/7 access to the care team, and caregiver training, plus respite services up to an annual cap so the caregiver can take a break ¹². Medicare waives the usual coinsurance and deductible for these services, so enrolled families pay nothing for them ¹³. The program is voluntary and does not change regular Medicare benefits, but it is not open to people enrolled in the Medicare hospice benefit or PACE, or living in a long-term nursing home ¹².

Note: The Alzheimer's Association runs a free 24/7 Helpline at 800-272-3900, staffed by specialists who provide information, local resources, and support in more than 200 languages, at any hour.

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RetiredWiki. (2026, July 18). Dementia and Alzheimer's disease. https://retiredwiki.com/article/dementia