Glutamate and its relation to periodontal disease, diabetes mellitus and cognition before and after scaling and root planing -An observational study

Periodontal disease (PD) is the leading cause of tooth loss in adults, and it signifies long-term exposure to inflammation. Each additional tooth loss has been associated with a 1.41 percent increase in the risk of cognitive impairment. Tooth loss is associated with poor masticatory function and it may affect stimulation of the central nervous system. Limited masticatory force and chewing capacity are associated with impaired cognitive function.

Evidence supports a clinical association between type 2 diabetes mellitus and PD. A chronic low-grade inflammatory state induced by type 2 diabetes mellitus may trigger worsening of periodontitis and is also an important pathophysiological mechanism underlying cognitive impairment and dementia. Decreased cognitive flexibility in diabetic individuals is well known.

Glutamate, the main neurotransmitter of the central nervous system, is a non-essential amino acid. It plays a key role in the development and function of normal brain activity, is a key factor involved in memory and learning and is also a promising marker of metabolic dysfunction. When glutamate concentrations are low in the brain there is poorer performance in several cognitive tests like the trail making tests (TMT A & B). Glutamate also has a pivotal role in transamination reaction that further upregulates in proteolysis and gets accelerated in chronic periodontitis during collagen destruction. Circulating glutamate has also shown to increase in diabetic individuals and is a strong predictor of waist circumference (WC).

Periodontal treatment reduces systemic inflammation and exposure to Porphyromonas gingivalis. This can improve insulin resistance which has been linked to the development of type 2 diabetes mellitus & might also reduce or delay the development of cognitive decline. Scaling and root planing (SRP) is the most commonly performed procedure for the treatment of periodontitis. We therefore hypothesized, that periodontitis, if positively associated with type 2 diabetes mellitus & cognition, SRP could lead to improvement in cognition and influence glutamate levels. Till date, the role of glutamate in the pathologic processes linking PD, diabetes mellitus & cognition is unclear. Hence the aim of this study is to correlate levels of salivary & serum glutamate in individuals with generalized periodontitis and type 2 diabetes mellitus & to evaluate the effect of SRP on glutamate and cognition.