Oral Health Interventions Improve Cognition, Microbiome in Alzheimer Disease

In patients with mild Alzheimer disease (AD), the use of oral health intervention strategies has been shown to be effective in modifying subgingival microbiota differences and slowing cognitive decline, according to a randomized controlled study published in Geriatric Nursing.

Researchers sought to determine the effect of an oral health intervention on disease progression in patients with mild AD and to compare the effectiveness of various oral health intervention strategies. Oral health, which has been linked to cognitive decline, is an area of emerging research in AD, although the exact mechanism is unclear. It is well known that promoting oral health is critical for healthy aging among older individuals.

The primary study outcome was oral health evaluation according to the Kayser-Jones Brief Oral Health Status Examination (BOHSE). Secondary outcomes included cognition assessment by Mini-Mental State Examination (MMSE), Neuropsychiatric Inventory (NPI), Nursing Home Adjustment Scale (NHAS), and Alzheimer’s Disease Cooperative Study-Activities of Daily Living (ADCS-ADL), along with oral microbiota.

The researchers hypothesized that oral health interventions would have beneficial effects on oral health, oral microbiota, and cognition at 6 months in patients with mild AD.

A total of 66 patients were randomly assigned to the intervention (n=33) or control (n=33) groups. After 6 months, there were 33 participants remaining in the
intervention group and 33 remaining in the control group. The mean participant age
was 82.85±6.00 years; the mean time spent in education was 10.97±4.51 years. Overall, 71.2% of the participants were female. Hypertension was reported in 59.1% of the participants and diabetes in 21.2%. The mean number of natural teeth per participant was 19.80±7.66; the mean number of dentures per participant was 3.36±5.92.

Data were obtained at baseline and at week 24. Subgingival plaque samples were obtained from 66 individuals after fasting overnight and prior to their brushing teeth after 24 weeks. Oral microbiota were analyzed with the use of 16S rRNA sequencing. The oral health intervention strategies used included structured visits (3 times per week), oral self-care (3 times per week), and self-management training (45 minutes per session, 1 time per week).

The researchers found the oral health intervention had statistically significant effects on BOHSE scores (P <.001), MMSE scores (P =.003), NPI scores (P <.001), NHAS scores (P =.030), and ADCS-ADL scores (P <.001). Subgingival plaque in patients with AD demonstrated differences in the diversity and abundance of oral microbiomes, with a higher abundance of normal oral flora in the intervention group.

Several limitations of the present study include the lack of species discrimination. Further, the study focused only on samples obtained before and after the 24-week intervention, without considering how microbiota may change over time. Thus, it appears that in order to fully understand the effect of oral microbiota on risk for AD, a systematic study is necessary, which should include a large-scale cohort study, as well as an analysis of the characteristics of oral microbiota.

According to the researchers, “A low-cost intervention based on self-determination theory, cognitive reserve hypothesis, and neuroinflammation improved cognitive performance and microbiome in patients with mild AD after 6 months.”

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.