Researchers from the Karolinska Institutet and Karlstad University in Sweden looked at tooth loss, chewing ability and cognitive function in a random nationwide sample of 557 people aged 77 or older.
The study found that those who had difficulty chewing hard food such as apples had a significantly higher risk of developing cognitive impairments.
This correlation remained even when controlling for sex, age, education and mental health problems, variables that are often reported to impact on cognition.
Whether chewing ability was sustained with natural teeth or dentures also had no bearing on the effect.
The older we become the more likely it is that we risk deterioration of our cognitive functions, such as memory, decision-making and problem solving, researchers said in a statement.
Research indicates several possible contributors to these changes, with several studies demonstrating an association between not having teeth and loss of cognitive function and a higher risk of dementia.
One reason for this could be that few or no teeth makes chewing difficult, which leads to a reduction in the blood flow to the brain.
