People who had a high dose of the common jab had a lower risk
A common vaccine millions take every year has been linked to ‘significantly lower’ dementia risk in elderly people. A large observational study published in Neurology found that receiving a high-dose flu vaccine is associated with a lower risk of Alzheimer’s disease in adults aged 65 and older.
The findings were led by researchers at the McGovern Medical School at UTHealth in Houston. In the UK, there are currently estimated to be 982,000 people living with dementia, the Alzheimer’s Society says, rising to 1.4 million in 2040.
In the retrospective cohort study, titled ‘Risk of Alzheimer Dementia After High-Dose vs Standard-Dose Influenza Vaccination’, researchers analysed health data from roughly 165,000 older adults who received either a high-dose or standard-dose influenza vaccine. They found that the high-dose vaccine reduced the risk of Alzheimer’s disease in those 65 and older by nearly 55% over a roughly two-year period.
Previous findings by the same team showed that the standard-dose vaccine was associated with a 40% reduced risk over a four-year period. The high-dose influenza vaccine contains four times the antigen, which is the component that generates an immune response, of the standard-dose versions.
The study’s authors suggest that the “enhanced [flu vaccines] confer greater protection against influenza infection”. They add: “Thereby decreasing risk of severe illness and the associated systemic inflammation that can promote neuroinflammation and neurodegeneration”.
Commenting on the results, the researchers also said: “High-dose influenza vaccination is associated with reduced AD risk compared with standard-dose vaccination in adults ≥65 years, with a stronger effect among women. This study provides Class II evidence that treatment with H-IIV vs S-IIV was associated with decreased incident dementia in individuals ≥65 years of age captured in this US health care claims database.”
While both men and women showed a lower risk of Alzheimer’s after receiving the high-dose flu vaccine compared with the standard-dose version, the protective effect appeared to be more consistent and lasted longer in women.
The study’s strengths include its large sample size and its design, which compared vaccinated groups. However, the researchers noted limitations, including “healthy-user bias”, the possibility that people who seek high-dose vaccines also seek health care in ways that affect dementia risk, and reliance on claims data that may have misclassified Alzheimer’s disease.
The authors say further research is needed to better understand vaccine dose, immune response, and long-term cognitive outcomes. As well as studies to determine whether vaccination can influence disease progression after symptoms have begun.
In England, more than 18.2 million patients registered with a GP were recorded as having received the flu vaccine during the 2024 to 2025 season. As of late November 2025, the vaccination rates showed that 70% of people over 65, 42% of pregnant women, and 71% of residents in care homes were vaccinated.
Who should have the flu vaccine?
According to the NHS, the flu vaccine is recommended for people in the UK who are at higher risk of serious illness from flu. It’s offered on the NHS every year in autumn or winter.
You can get the free NHS flu vaccine if you:
- are aged 65 or over
- have certain long-term health conditions
- are pregnant
- live in a care home
- are the main carer for an older or disabled person, or receive a carer’s allowance
- live with someone who has a weakened immune system
Frontline health and social care workers can also get a flu vaccine through their employer.
Symptoms of Alzheimer’s disease and what causes it?
According to the NHS, Alzheimer’s disease is the most common cause of dementia in the UK. It says: “Dementia is the name for a group of symptoms associated with an ongoing decline of brain functioning. It can affect memory, thinking skills and other mental abilities. The symptoms of Alzheimer’s disease progress slowly over several years. Sometimes these symptoms are confused with other conditions and may initially be put down to old age.”
In the early stages, the main symptom of Alzheimer’s disease is memory lapses. For example, someone with early Alzheimer’s disease may:
- forget about recent conversations or events
- misplace items
- forget the names of places and objects
- have trouble thinking of the right word
- ask questions repetitively
- show poor judgement or find it harder to make decisions
- become less flexible and more hesitant to try new things
As Alzheimer’s disease develops, memory problems will get worse. Other symptoms may also develop, such as:
- increasing confusion and disorientation – for example, getting lost, or wandering and not knowing what time of day it is
- obsessive, repetitive or impulsive behaviour
- delusions (believing things that are untrue) or feeling paranoid and suspicious about carers or family members
- problems with speech or language (aphasia)
- disturbed sleep
- changes in mood, such as frequent mood swings, depression and feeling increasingly anxious, frustrated or agitated
- difficulty performing spatial tasks, such as judging distances
- seeing or hearing things that other people do not (hallucinations)
The behaviour of people with Alzheimer’s disease can also change. For example, they may:
- be aggressive, such as hitting or shouting
- become upset or restless
- call out or repeat the same question again and again
A number of other symptoms may also develop as Alzheimer’s disease progresses, such as:
- difficulty eating and swallowing (dysphagia)
- difficulty changing position or moving around without assistance
- weight loss – sometimes severe
- unintentional passing of urine (urinary incontinence) or stools (bowel incontinence)
- gradual loss of speech
- significant problems with short and long-term memory
