Investigation of the Relationship Between Periodontitis and Alzheimer's Disease in Terms of Blood Parameters

Blood Markers in Periodontal Inflammation and Alzheimer's Disease: A Retrospective Case-Control Study

The aim of this study was to analyse the possible relationship between periodontal inflammation and Alzheimer's disease and to investigate the role of blood parameters in this relationship.

This retrospective case-control study will include individuals who were clinically and radiographically examined, diagnosed with periodontal disease, read and signed informed consent forms between March 2022 and July 2025 at the Periodontology Departments of Bezmialem Vakif University, Uskudar University and Bolu Abant Izzet Baysal University Faculty of Dentistry.

In this study, two groups will be formed as a case group consisting of individuals with periodontitis diagnosed with probable Alzheimer's disease according to NINCDS-ADRDA and DSM-V diagnostic criteria and a control group consisting of individuals with periodontitis only.

Patients who underwent periodontal evaluations at six sites per tooth, with the following parameters recorded-plaque percentage, probing pocket depth, percentage of bleeding on probing, clinical attachment level, number of teeth, and periodontal inflamed surface area (PISA)-will be included in the study.

Compliance with the inclusion and exclusion criteria will be verified through patient files and digital records. In individuals with a probable diagnosis of Alzheimer's disease according to NINCDS-ADRDA and DSM-V diagnostic criteria, disease stage as determined by the Clinical Dementia Rating scale and Standardized Mini-Mental Test (SMMT) scores will also be recorded.

Hematological data will be obtained from patients' recorded complete blood count test results and the following parameters will be utilized:

• White blood cell count, neutrophil, lymphocyte, monocyte, eosinophil, basophil counts and percentages, neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR)
• Platelet count, platelet/lymphocyte ratio (PLR), platelet distribution width (PDW), mean platelet volume (MPV), plateletcrit (PCT)
• Erythrocyte count, hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), red blood cell distribution width (RDW)
• In addition, inflammation indicators such as pan-immune inflammation value (PIV), systemic immune-inflammation index (SII) and hemoglobin/erythrocyte ratio (HRR), which are formulated from the above parameters, will also be recorded.

Inclusion Criteria:

• Between March 2022 and July 2025, those who applied to the Periodontics Departments of the Dentistry Faculties of Uskudar University, Bezmialem Vakif University and Bolu Abant Izzet Baysal University,
• Informed consent form was obtained during the examination,
• Over 50 years of age,
• Non-smoker and non-alcoholic,
• No psychiatric disorders affecting cognitive status and no medication affecting cognitive status,
• Complete blood count was performed within the 6 months prior to the date of inclusion in the study,
• No dental treatment within the last 1 year,
• Periodontal examination was performed by expert periodontologists who calibrated the inter- and intra-examination,
• Individuals diagnosed with periodontitis as a result of periodontal examination and radiographic examination, and
• For individuals diagnosed with Alzheimer's disease: Recording their stage according to the Clinical Dementia Rating (CDR) and Standardized Mini-Mental Test (SMMT) scores

Exclusion Criteria:

• Individuals with fewer than 10 teeth,
• Individuals with uncontrolled systemic disease,
• Individuals who regularly use anti-inflammatories or corticosteroids