It may be difficult to envision how your teeth affect your mental abilities, but several studies have already shown a potential link between oral health and brain functioning. Up until now, the question lingered about which long-term dental issues contribute to the decline of cognitive abilities. It is an important issue since more than 55 million individuals worldwide suffer from dementia, a general term for a range of neurological conditions that cause a decline in mental acuity.

A new study by researchers at Hyogo Medical University in Japan aimed to identify the oral health factors that might predict declining changes in mental abilities among older adults over time.

Their study included 583 older Japanese adults — 201 were male and 382 female — with a mean age of 72.7 years. All lived independently.

Poor oral health had long-term effects on cognitive function in older adults.

At the start of the study, the participants' cognitive function was assessed using the Mini-Mental State Examination (MMSE). The MMSE is an 11- question assessment that screens for cognitive impairment in older adults and helps to track changes over time. Sample questions included: What city, state and country are we in? Name three unrelated objects and repeat the following: “No ifs ands or buts.”

A baseline measurement of oral health was also taken which included:

1) The number of remaining teeth, an issue because our teeth help to break down food so it can be swallowed and digested;

2) Masticatory performance or the ability to chew effectively, which also measures the ability to break down food into smaller pieces for chewing;

3) Occlusal force which is the force exerted on the teeth when the jaws come together during biting and chewing;

4) Oral diadochokinesis (DDK), a common tool for evaluating oral-motor skills used to assess tongue and lip motor function;

5) Tongue pressure which plays a critical role in swallowing since it helps to create food shape and manipulation, as well as aids the transportation of food from the mouth to the throat.

The participants also completed a self-administered questionnaire that collected data including age, sex and medical history. In addition, they were interviewed to gather information about educational level, history of smoking, level of hypertension, as well as their quality of life. The volunteers were also given a walking speed test, one-leg standing test and a hand grip strength evaluation.

Overall, the research revealed that poor oral health had long-term effects on cognitive function in older adults. One of the five factors studied, diadochokinesis, the ability to quickly alternate between opposite muscle movements, such as opening and closing your fists or, in this case, your jaw, was shown to be the strongest potential risk factor for cognitive decline. DDK evaluation may enable early detection and intervention and potentially delay or prevent cognitive decline.

To maintain good oral health the American Dental Association (ADA) recommends:

  • Brush twice a day: Brush your teeth for two minutes each time, using a soft-bristled toothbrush and fluoride toothpaste.
  • Floss daily: Clean between your teeth once a day with floss or another interdental cleaner.
  • Limit sugary drinks and snacks: Focus on a balanced diet.
  • Make regular visits to your dentist: See your dentist for checkups and cleanings at least once a year.

The study is published in Scientific Reports.