Alzheimer's Disease Is Divided Into 7 Stages — Which Stage Is Your Loved One In?

Many families only think about taking an older adult to see a doctor when they "can't remember things" or even "get lost while out walking." But in reality, from the time pathological changes first appear in the brain to the emergence of obvious clinical symptoms, Alzheimer's disease has already been quietly smoldering for 10 to 20 years. According to the latest international criteria released in 2024, Alzheimer's disease is a continuous disease spectrum. The medical community has now divided it into 7 detailed stages. Understanding these 7 stages is not just about figuring out where your loved one fits — it's about seizing those fleeting windows for intervention.[1]

01 Preclinical Phase (Stages 0–2): More Than a Decade of Silent Latency[2]

During this phase, patients' basic daily functioning is completely normal, making it extremely easy for family members to overlook. Yet this is precisely the best time to carry out non-pharmacological interventions such as neuromodulation (secondary prevention).

 

Stage 0 (Pathogenic Gene Stage): No clinical symptoms and no abnormalities in core biomarkers. This is seen mostly in people carrying familial AD pathogenic genes or in those with Down syndrome–related AD.

 

Stage 1 (Core Biomarker–Positive Stage): The patient has no symptoms at all, but Aβ protein deposition has already begun in the brain.

The key breakthrough is this: according to the 2024 new criteria, as long as the blood test for the p-tau217 biomarker is positive, the person meets the biological diagnostic criteria for AD.[3]This stage may last for years or even more than a decade.

 

Stage 2 (Subjective Cognitive Decline, SCD): The patient persistently feels that their memory is declining and worries about it, but when they go to the hospital for cognitive scale testing, the results are completely normal.

 

[Highly Warning Signs to Watch For]: Research shows that during this preclinical phase, which can last 5–10 years, patients may already begin to show behavioral and psychological symptoms of dementia (BPSD).

 

For example:

1.Personality and emotional changes: A person who once loved socializing suddenly becomes apathetic or mildly depressed.

 

2.Unusual delusions and repetitive behaviors: They misplace something themselves but firmly believe it was stolen (delusion of theft); they repeatedly ask the same question or repeat the same action.

 

02 Symptom-Onset Phase (Stages 3–4): The Critical Line of Defense for Medication Intervention

Once this phase begins, brain damage starts to become visible. If anti-Aβ monoclonal antibodies and other disease-modifying therapies (DMT) can be used promptly during these two stages or earlier, they can effectively stop or slow disease progression.

 

Stage 3 (Mild Cognitive Impairment, MCI): Lasts 3–7 years. This was previously often regarded as the "early stage" of AD. At this point, cognitive testing scales can already detect clear decline.

Characteristics: Episodic memory is affected first — the person forgets what was just said or done (for example, forgetting breakfast eaten half an hour ago). However, basic daily living skills remain intact, and the patient can still care for themselves. At this stage, medication must be paired with non-pharmacological interventions.

 

Stage 4 (Mild Dementia): Lasts 1–5 years. At this point, the patient has obvious cognitive problems, and basic daily life is mildly affected.

 

Characteristics:

1.Time disorientation: They cannot keep straight when things they have experienced actually happened.

 

2.Impaired semantic memory: Looking at a familiar comb or bar of soap, they cannot name it.

 

3.Decline in complex daily living skills: Cooking is no longer as good as it used to be, cleaning is not thorough, and at the supermarket they may repeatedly buy the same vegetable that is already stuffed in the refrigerator. Fine motor skills may also be affected (such as crooked handwriting or buttoning clothes incorrectly).

 

03 Middle and Late Dementia (Stages 5–6): The Full-On Surge of Caregiving Pressure

By this stage, the patient's ability to live independently comes to an end, and damage across different types of memory intensifies across the board. Families will face enormous caregiving challenges.

 

Stage 5 (Moderate Dementia): Lasts 5–10 years.

 

Characteristics:

1.Place disorientation: There is a risk of getting lost as soon as they leave the house. Long-term memory begins to blur (they no longer recognize familiar loved ones).

 

2.Psychiatric and rhythm disturbances: "Sundowning" appears (irritability and agitation in the evening), along with various hallucinations, anxiety, and depression.

 

3.Significant decline in executive function: Bathing, dressing, and eating all require help from family members. This stage requires round-the-clock care and support.

 

Stage 6 (Severe Dementia): Lasts 1–3 years. In the final stage, the patient loses nearly all cognitive abilities and cannot express their needs.

 

Characteristics:

Not only can they no longer recognize people, but basic activities of daily living (such as eating and toileting) become completely dependent on others. They may even forget how to chew, and swallowing may be accompanied by choking.

 

At this point, treatment focuses mainly on low-dose maintenance medication and meticulous professional care. It is especially important to note that at this stage, aspiration pneumonia caused by swallowing difficulties, or pressure ulcer infections caused by long-term bed rest, can easily occur — and these are often the main causes threatening the patient's life.

 

Alzheimer's disease is a continuous process, and there is some overlap between stages. Understanding these 7 stages is meant to remind everyone: do not wait until an older adult "can no longer recognize people" to realize they are ill. When an elder complains that their memory is far worse than before, or shows unfounded suspicion, it is time to seek medical care promptly and complete biomarker testing (such as blood p-tau217), to determine which stage of the disease they are in and develop an individualized intervention plan. That is the fundamental way to slow disease progression and improve quality of life.

 

[1] Jack CR Jr, et al. Revised criteria for diagnosis and staging of Alzheimer's disease: Alzheimer's Association Workgroup. Alzheimer's & Dementia. 2024;20(8):5143–5169.

https://pubmed.ncbi.nlm.nih.gov/38934362/

 

[2] Sperling RA, et al. Toward defining the preclinical stages of Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimer's & Dementia. 2011;7(3):280–292.

https://pubmed.ncbi.nlm.nih.gov/21514248/

 

[3] Palmqvist S, et al. Discriminative accuracy of plasma phospho-tau217 for Alzheimer disease vs other neurodegenerative disorders. JAMA. 2020;324(8):772–781.

https://pubmed.ncbi.nlm.nih.gov/32722745/