Less than half of people over 40 have had free health checks that can reduce the risk of dementia, according to the British NHS.
About 15 million people are eligible for a 20-minute assessment, which filters heart problems, kidney disease and type 2 diabetes, over the past five years.
Dementia and Alzheimer's disease remain the leading causes of death in England and Wales in 2017, accounting for nearly 13% of all deaths registered, according to the Office for National Statistics.
Someone who has a stroke or has diabetes or heart disease is about twice as likely to develop vascular dementia, according to the Alzheimer's Society.
"The beginning of the new year is the right time to commit to taking simple, free and potentially life-saving steps towards a healthier life," said Alistair Burns, national clinical director for dementia in the NHS England.
Everyone between the ages of 40 and 74 without a pre-existing health condition automatically qualifies for checks every five years. This is part of the UK NHS goal to improve early diagnosis of dementia.
Laura Phipps, head of communications in Alzheimer's Research UK, said: "There is good evidence to show that what is good for the heart is also good for the brain, but while 77% of people believe they can reduce their risk of heart disease, only 34% people know that they can reduce the risk of dementia.
"Research shows that middle age is a very important time to take actions that will help maintain a healthy brain towards the next life. With dementia now the leading cause of death in the UK, we must encourage everyone to take positive steps to maintain good brain health throughout their lives and towards older age.
Jamie Waterall, who leads the program in Public Health England, said: "NHS health checks see the main causes of premature death and poor health, but more importantly supporting people to take action reduces the risk of preventable conditions such as dementia and heart disease.
The NHS England said the national target was to ensure at least two-thirds of people living with diagnosed and treated dementia had been met for the past two years.