In a recent study, experts have created a shortlist of environmental factors that may possibly contribute to our risk of developing dementia.
The list includes exposure to air pollution and a lack of vitamin D but the evidence is not yet sufficient to draw solid conclusions.
Dementia is known to be associated with lifestyle factors such as high blood pressure in mid life, smoking, diabetes, obesity, depression and low educational attainment, as well as genetic factors.
These risk factors however, leave around a third of dementia risk unexplained.
Researchers sought to determine whether other issues are at play, including the environment.
The team reviewed dozens of previous studies that have considered environmental risk factors linked to dementia.
They found that lack of vitamin D produced by the body through exposure to sunlight and air pollution was implicated, along with occupational exposure to some types of pesticide.
Excessive levels of minerals found in drinking water may be linked to the disease but the evidence was mixed.
Dementia is a major global public health crisis that is expected to grow as people live longer.
Almost 47 million people live with dementia worldwide and this is predicted to increase to more than 131 million by 2050.
There is a growing consensus among doctors that a significant proportion of cases could be prevented or delayed by addressing environmental factors linked to the disease.
The research was published in the journal BMC Geriatrics.