Monday, March 25, 2019

More Information on Periodontal Disease and the Potential Increased Risk for Dementia

In case you haven’t noticed (and I’ll bet that you have) the mouth is connected to the rest of the body.  Following that thought to its logical conclusion, therefore diseases of the mouth can also cause diseases of the body.  For years now we’ve been seeing more and more data showing bacteria from the mouth showing up in infections and lesions throughout the body.  The latest investigations have been seeing links between periodontal disease and dementia, up to and including Alzheimer’s disease.
While those of us in the trenches of clinical dentistry have been aware of these links for some time now, this type of information is not always something that makes its way into the general news cycle so often times the public isn’t aware of important information like this.  However, recently a study that appeared in the Journal of the American Geriatrics Society was discussed in an article in Forbes.  When information gets into a publication like Forbes, I’m optimistic that the general public will soon be aware.
The study titled Association of Chronic Periodontitis on Alzheimer's Disease or Vascular Dementia included 262,349 patients and they were followed over 10 years (from 2005-2015).  The study appears to be well done and solidly performed.  It can be read in its entirety at the Wiley Online Library.  Which also includes graphs and tables.  A portion of the study is included below:
Dementia is considered one of the leading causes for increased disability‐adjusted life years among older adults.1 It was estimated that approximately 36 million people had dementia in 2010.2 Furthermore, the prevalence of dementia is expected to increase globally due to the rising life expectancy worldwide. According to one report using the United Nations worldwide population forecasts, it was estimated that 1 in 85 individuals will be diagnosed with Alzheimer's disease (AD) by 2050.3 Interestingly, a 2014 study suggested that a 20% reduction of key exposures could lead to a 15.3% decrease in dementia prevalence by 2050, highlighting the importance of determining risk factors that could lead to dementia.4Therefore, the need is increasing to identify and manage risk factors associated with dementia. One such risk factor is chronic periodontitis (CP).
Multiple animal5 and human6-9 studies previously showed an association between CP and dementia. Most recently, a retrospective cohort study demonstrated that CP patients had a significantly higher risk of AD compared with those without CP.10 However, previous studies had limitations in the relatively small sample size, no consideration of dementia outside of AD, and by the lack of consideration of important confounders such as lifestyle behaviors. Because one of the suggested mechanisms of the risk‐increasing effect of CP on dementia is by inducing vascular damage,11, 12 other types of dementia such as vascular dementia (VD) may be at elevated risk among CP patients. Furthermore, lifestyle behaviors such as smoking, alcohol consumption, and physical activity are all considered risk factors for both CP and dementia, and they are thus potentially important confounders that must be considered.
Therefore, further studies on the association between CP and dementia are needed using a large study population, with consideration of an extensive number of covariates, and determining the risk of other types of dementia such as VD. In this longitudinal population‐based study, we determined the association of CP on AD and VD using the Korean National Health Insurance Service (NHIS) database using a wide range of covariates including smoking, alcohol consumption, and physical activity.
Study Population
The study population was derived from the National Health Insurance Service‐Health Screening Cohort (NHIS‐HEALS). In South Korea, the NHIS provides mandatory health insurance covering nearly all forms of healthcare for all Korean citizens.13 Records from inpatient and outpatient department visits including diagnosis, drug prescriptions, treatment, and surgical procedures are collected. Furthermore, the NHIS provides biannual mandatory health screening examinations for all enrollees 40 years or older.14 The health screening examination consists of a self‐reported questionnaire on health behavior, body measurements including height, weight, and blood pressure, and blood and urine tests. From this claims database, the NHIS provides a part of its data for research purposes that include information on inpatient and outpatient hospital use, drug prescriptions, death dates, and results from health screening examinations. The NHIS database was previously used for multiple epidemiological studies, and its validity is described in detail elsewhere.14, 15
Among 313 537 participants aged 50 or older, we excluded 31 293 participants who were diagnosed with CP during 2002. Furthermore, we excluded 16 173 participants with missing values on covariates. Finally, 1942 and 1780 participants who were diagnosed with dementia or died before the index date were excluded, respectively. The final study population consisted of 262 349 participants. All participants were grouped as healthy (no CP) or diagnosed with CP during 2003‐2004. Starting from January 1, 2005, the participants were followed up until date of dementia diagnosis, date of death, or December 31, 2015, whichever came first.
This study was approved by the institutional review board of Seoul National University Hospital (IRB number E‐1801‐019‐912). The requirement for informed consent was waived because the NHIS‐HEALS database is anonymized with strict confidentiality guidelines.
Key Variables
CP was defined as being diagnosed with CP according to the International Classification of Diseases, Tenth Revision (ICD‐10 code K05.3), and having undergone at least one of the CP‐related treatments.16 The considered CP‐related treatments were subgingival curettage, periodontal flap operation, gingivectomy, and odontectomy.16 Participants who were not diagnosed with CP and did not undergo CP‐related treatment were considered healthy. Dementia was defined as being prescribed with dementia‐related drugs under a diagnosis for AD (ICD‐10 codes F00, G30) or VD (ICD‐10 code F01).17 The considered dementia‐related drugs were donepezil, galantamine, rivastigmine, and memantine.17
The considered covariates included age (years, continuous), sex (categorical, men and women), household income (categorical, first, second, third, and fourth quartiles), smoking status (categorical, never, past, and current smoker), alcohol consumption (categorical, none, 0‐1, 1‐2, 3‐4, and ≥5 times per week), physical activity (categorical, none, 1‐2, 3‐4, 5‐6, and 7 times per week), body mass index (continuous, kg/m2), systolic blood pressure (continuous, mm Hg), fasting serum glucose (continuous, mg/dL), total cholesterol (continuous, mg/dL), and Charlson Comorbidity Index (categorical, 0, 1, 2, ≥3). Household income was derived from the insurance premium, and body mass index was calculated by dividing height in meters by weight in kilograms squared.
Statistical Analysis
Cox proportional hazard regression was used to determine the adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) of overall dementia, AD, and VD according to CP. Furthermore, we conducted a stratified analysis for the association of CP on dementia according to subgroups of smoking, physical activity, and alcohol consumption. Finally, a sensitivity analysis on the effect of CP on dementia after excluding participants diagnosed with dementia up to 5 years after the index date was conducted.
Statistical significance was considered at P < .05 in a two‐sided manner. All data analyses were conducted using SAS software v.9.4 (SAS Institute Inc, Cary, NC).
Table 1 shows the descriptive characteristics of the study population. Among 262 349 participants, 216 005 did not have CP and 46 344 were diagnosed with CP. The mean age for healthy and CP patients were 60.4 years (standard deviation [SD] = 7.7) and 60.2 years (SD = 7.3), respectively. The percentages of male healthy and CP patients were 49.4% and 56.8%, respectively. Compared with healthy participants, CP patients tended to have higher proportions of men, have higher household income, smoke, consume more alcohol, and exercise more.

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