Which of the following is a recognized risk factor for developing dementia?

Pollution or toxin exposure is a recognized risk factor for developing dementia due in part to the impact these environmental factors can have on brain health. Studies have shown that long-term exposure to air pollution and certain chemicals can increase inflammation and oxidative stress in the brain, leading to neurodegenerative processes associated with dementia. These toxins may also impair cognitive function and contribute to the onset of dementia by damaging brain cells, facilitating the accumulation of amyloid plaques, and affecting vascular health.

In contrast, the other options do not have the same strong evidence linking them to an increased risk of dementia. A high protein diet, for instance, has not been consistently associated with cognitive decline, and excessive exercise is generally beneficial for overall brain health. While vitamin D deficiency has been studied for its potential links to cognitive health, the relationship is less clear than that of pollution and toxins, and it is not universally recognized as a definitive risk factor for dementia.