Schizophrenia is a common functional psychotic disorder and a chronic psychotic disorder that affects the patient’s thoughts causing delusions and hallucinations. In this cross-sectional descriptive study, an attempt was made to explore the possible association between schizophrenia and periodontal diseases and its correlation with cortisol levels. Cortisol is a glucocorticoid steroidal hormone and secretion of which is controlled by hypothalamic pituitary adrenal axis (HPA). Analysis of cortisol in saliva is highly promising, accurate and non-invasive method for assessment of chronic stress and HPA axis [17, 18]. A clinical prospective study of Zoja et al., that compared the serum cortisol levels between schizophrenia patients and healthy controls has concluded that elevated serum cortisol levels may be considered as a biomarker for the diagnosis of schizophrenia and may be used as a significant predictor for positive response to antipsychotic treatment in schizophrenia patients with acute exacerbation . According to the results of another study by Kornetova et al., patients who underwent treatment, and does not present notable clinical signs of schizophrenia may have moderately lowered levels of salivary cortisol which is a reflection of relenting psychotic symptoms as well as a direct effect of atypical antipsychotic drugs on HPA axis activity. [6, 20, 21].
In the present study, cortisol levels were lower in schizophrenic patients than healthy patients and there was no correlation between cortisol and clinical periodontal parameters. This could be due to the possible effect of schizophrenic patients undergoing medical treatment which can be explained by the earlier studies on schizophrenic patients that have demonstrated the reduction in cortisol levels of schizophrenic patients following antipsychotic treatment [22, 23]. A by Rady et al., has found reduction in serum cortisol level of chronic schizophrenic patients on antipsychotics . It is evident from the literature that cortisol has negative effects on periodontal disease progress and severity. Higher cortisol levels are also associated with severity and progression of periodontal disease. However, lower cortisol levels found in our study rules out the possible role of cortisol in periodontal disease severity associated with schizophrenic patients undergoing antipsychotic therapy.
Another finding of this study is increase in indicators of periodontal disease activity such plaque index, gingival index, probing depth and clinical attachment loss in schizophrenic patients than healthy. A study by Shreya et al., has demonstrated increased evidence of poor periodontal condition with higher GI, PI and PD in schizophrenic patients suggesting the possible link between periodontal disease and schizophrenia . However, Shreya et al., have not considered the possible role of cortisol, xerostomia and other risk factors associated with schizophrenia and periodontitis.
Both schizophrenia and periodontal diseases share some of the common risk factors such as stress, xerostomia and tobacco consumption with immunoinflammatory alterations playing major role. Xerostomia has been recognized as an important risk factor for dental diseases and its impact on the quality of life of sufferers . Emotional and psychological alterations and psychotropics induces xerostomia in patients with schizophrenia which may facilitate periodontal inflammation. In schizophrenia patients with chronic use of antipsychotic medications, such as aripiprazole, pernazine and risperidone, have a negative effect on salivary secretions, since salivary glands are neurobiologically regulated by autonomic nervous system, which influence the levels of transmitter substances and thereby affect the salivary gland function that lead to xerostomia which may negatively affect periodontal health [26, 27]. Eltas et al., reported that the side effects of antipsychotic medications and smoking caused severe periodontal disease in psychiatric patients . However, confounding factors such as xerostomia and tobacco consumption have been eliminated by subject selection criteria to rule out their possible influence on periodontal status focusing the role of cortisol.
The relationship between periodontal disease and schizophrenia could be bilateral. Host homeostatic changes induced by schizophrenia may enhance the severity and progression of periodontal disease. Periodontal disease may in turn influence the pathological course of schizophrenia through contributing to inflammatory load aggravating the symptoms. This possible link between periodontal disease giving rise to schizophrenia cannot be overlooked due to the presence of cytokine activity which is present both in schizophrenia and periodontal disease . A study by Dana Graves, has explained the role of chemokines on periodontal health in schizophrenic patients which may directly or indirectly modulate leukocyte recruitment and osteoclast formation . Greater probing depths and clinical attachment loss in schizophrenic patients found in this study suggesting greater periodontal destruction could be the result of exposure to cytokines such as interleukins and other inflammatory mediators produced in the pathophysiologic course of schizophrenia. Alterations in inflammatory related genes, genetic polymorphism of cytokines, proinflammatory cytokine dysregulation including upregulation in levels of IL-1β, IL-6, IL-9, TNF-α, TNF-β, PGE2 and CRP in schizophrenic patients can adversely influence the periodontal disease and its progression [30, 31]. The continued presence of inflammatory cytokines due to periodontal disease may have an influence on neurotransmitter mechanism in schizophrenia by modulating the dopaminergic metabolism thereby negating the effects of medication. IL-1β, a key cytokine in periodontal disease, has been shown to affect the neurotransmitters by enhancing dopamine survival and inhibiting glutamate release leading to hypofunction of N-Methyl-D-Aspartate (NMDA) glutamate receptors which may lead to schizophrenia. Similarly, elevated IL-6 levels, another cytokine implicated in periodontal disease, have been shown to be associated with duration of illness of schizophrenia [32,33,34]. This cytokine dysregulation may stem from psychotic drugs and/or immunological phenotype of schizophrenia.
As evidenced by the literature, systemic conditions pose greater risk for periodontal attachment loss as well share bilateral relationships. The findings of this study strengthen the relationship between systemic and periodontal diseases and can draw attention of dentists, periodontists and psychiatrists towards the association between schizophrenia and periodontal disease. And also forms basis to set the clinical guidelines for the management of periodontal diseases in schizophrenic patients. Understanding this association can enable the dentists and periodontists to structure and implement effective periodontal treatment plan.
The schizophrenic condition can possibly influence the prognosis of dental treatments, such as periodontal treatment, endodontic therapy, extraction etc. A case report by Lizett Castellanos-Cosano et al., showed no post operative complications following dental implant placements and it can be a suitable option for schizophrenic patients under psychiatrist’s consultation . However, there is scarcity of literature that assess the influence of schizophrenia on various dental treatments and there is necessity of more researches to explore this aspect. A systematic review suggests that patients with schizophrenia have worse oral health than the general population, but have received less dental care services and the oral health services should be taken into account in the patients with schizophrenia . Providing oral care for patients with schizophrenia can be challenging, because this disorder can prevent the patient from mindful participation in oral care which can be further compounded by the presence of motor, cognitive, social and behavioural impairments . The dentists should consider the possible influence of patients’ cognitive status, effects of antipsychotic drugs and possible interactions with dental drugs. Dentists must be familiar with the disease process so that they can communicate effectively with the patient, the treating psychiatrist and family members who serve as caregivers. .
The treatment interventions in schizophrenia may have influence on the association of this complex psychosis with periodontal disease. Hence, absence of drug free schizophrenic control group forms the limitation of this study. However, this study is the first of its kind that explored the relationship between schizophrenia and periodontal disease in relation to cortisol levels eliminating the confounders, such as stress, xerostomia and tobacco consumptions. Further longitudinal clinical studies are warranted to strengthen the causal–effect relationship between schizophrenia and periodontal disease.