Association of periodontal health indicators and major depressive disorder in hospital outpatients.

BACKGROUND: Major depressive disorder (MDD) has been associated with changes in behavioral, neurophysiological, and neuroendocrinological factors and thought to be one of the leading causes of disability worldwide. There are various evidences that depression and periodontitis may also be related. AIM: The aim was to evaluate the association between MDD and periodontitis in a convenience sample of hospital outpatients.
MATERIALS AND METHODS: Sixty individuals (30 subjects with MDD and 30 subjects without MDD) of age 26-67 years were included in the study. Depression was assessed by means of structured clinical interview for diagnostic and statistical manual of mental disorders. The periodontal clinical examination included the number of missing teeth, plaque index, gingival index (GI), probing pocket depth, and clinical attachment level (CAL).
RESULTS: Mean number of missing teeth per patient was 1.14 (±1.2 standard deviation [SD]) in the control group and 2.58 (±1.64 SD) in case group (P < 0.001). The amount of plaque was significantly higher in cases compared with control (P = 0.001). The patients had an average GI of 1.82 (±0.65 SD) compared to 1.14 (±0.81 SD) for the controls (P < 0.001). Mean probing depth and CAL were 4.67 (±0.8 SD) mm and 4.96 (±0.2 SD) mm in the case group and 2.6 (±2.2 SD) mm and 2.7 (±0.43 SD) mm in the control group, respectively (P < 0.05).
CONCLUSION: Our study confirms the significant association between depression and periodontitis and depression can be considered one of the important risk factors for periodontal diseases.

INTRODUCTION

The contribution of psychological factors to the development and progression of the periodontal disease has recently become an area of increased research activity. Studies indicated that there might be strong relationships between stress, depression, and periodontal disease demonstrating convincing linkages between depression and elevated cortisol levels, negligence of oral hygiene, pocket depth, attachment loss, and tooth loss.[1]

Bipolar disorder and major depressive disorder (MDD) are two major psychiatric disorders classified as mood disorders in the diagnostic and statistical manual of mental disorders (DSM-IV). Bipolar disorder is a mental illness characterized by periods of elevated mood and periods of depression. The elevated mood is significant and is known as mania or hypomania depending on the severity. Whereas, MDD is characterized by the presence of one or more major depressive episodes and no manic or hypomanic episodes. A depressive episode is defined as depressed mood or loss of interest accompanied by at least four additional symptoms of depression (significant weight change without being on a diet, insomnia or hypersomnia, agitation or psychomotor retardation, fatigue or loss of energy, feelings of uselessness or guilt, reduced ability to think or concentrate, and recurrent thoughts about death) for at least 2 weeks. According to these criteria, the symptoms may not be attributed to a general medical condition.[2]

Some authors considered depression to be one of the important risk factors for the development of periodontitis,[34] while others did not find an association between them.[56] There are a variety of hypotheses proposed to show the association between depression and periodontitis. An explanation on the behavioral level might be that depressed patients adopt habits which are harmful to periodontal health, such as negligent oral hygiene, intensification of smoking, changes in eating habits; and neglect regular dental check-ups as a result of reduced drive, mood, affectivity, and interest.[7] On the neuroendocrinological level, the relation between depressive mood and periodontitis has been attributed to an impaired immune response caused by a disturbance in the hypothalamo-pituitary-adrenocortical (HPA) system.[891011] Although decreased immune activity has been observed in patients with depression, the clinical implications of these findings for diseases such as cancer and infectious diseases are still controversial. Moreover, the clinical relevance of these immunological alterations in the course of infectious diseases, especially periodontal disease, has not been well established.[12]

Taking antidepressant drugs has negative effects on periodontal health. Reduced saliva secretion as a consequence of antidepressant medication is one of the main reasons which make the oral environment susceptible to periodontal diseases.[1314] According to Friedlander and Norman,[15] depression is also related to increase anticholinergic activity. There are several studies regarding depression and decreased salivary flow. Strongin and Hinsie[16] compared parotid gland flow in six manic-depressive patients with flow rates in normal control subjects and found that manic group flow rates fell within the normal range, whereas in the depressed subjects flow rates were below the lowest rate of the normal group.

There is a need for more research to establish the relationship between periodontal disease and depression. Therefore, the objective of the present study was to compare periodontal clinical parameters between patients with MDD and healthy controls without diagnosed depression.

MATERIALS AND METHODS

Study sample

Prior to the start of the study ethical clearance of the protocol was obtained from Ethical Committee of the Institutional Review Board (Navodaya Dental College and Hospital). This study was conducted in the Department of Periodontology at Navodaya Dental College and Hospital, Raichur. The sample consisted of 60 physically healthy subjects, recruited from Navodaya Medical College and Hospital. All subjects signed an informed consent before taking part in the study and were assured that all information gathered in the course of study will be kept confidential. All participants were assessed using the Structured Clinical Interview for DSM IV (SCID).[17] Current severity of depression was evaluated with the Hamilton Depression Scale (HAM-D-31).[18]

Subjects in the age group of 26–67 and having at least 20 teeth in the mouth were included in the study. Subjects with uncontrolled diabetes, HIV infection, cardiovascular disease, psychiatric Axis I disorders (delirium, dementia, schizophrenia, eating disorders, organic mental disorder, type 1 or 2 bipolar disorder, psychotic depression, and schizoaffective disorder), undergone periodontal treatment 6 months before examination, alcohol or drug dependence within 6 months before the study and having history of epilepsy, infectious or autoimmune disease were excluded from the study.

The case group subjects were randomly selected from a larger group of available hospital outpatients from the Department of Psychiatry, Navodaya Medical College. They were having one or more recurrent depressive episodes and a score of at least 15 points on the HAM-D-31. The control group comprised of same number of subjects, having age (±3 years) and as much as possible other demographic variables-matched. They were recruited from hospital staff and volunteers by means of simple random sampling and were not having MDD. From both patients and controls, socioeconomic data's, as well as information pertaining to smoking habits were obtained. Subjects were identified as nonsmokers if they had never smoked, current smokers if they had a current smoking habit, and former smokers if they reported that they had quit smoking.

Psychometric instruments

A diagnostic instrument and observer rating scales were used for this assessment. SCID version 2.0 based on DSM-IV criteria was used for psychiatric diagnosis.[17] Interviews were conducted by trained interviewer. The Hamilton Depression Rating Scale version 31 was used to assess the depression severity.[18] These assessments were done according to intensity and frequency within a specific period. The depressive syndrome was defined as chronic when symptoms were present for at least 2 years without remission lasting 2 months or longer.

Procedure

All participants underwent a standard physical examination and their medical history was recorded. Clinical diagnoses were made by one experienced psychiatrist using the SCID. Patients with depression met the DSM-IV criteria for MDD. All participants were physically healthy. The participants were invited for periodontal clinical examination. The periodontal clinical examinations were carried out using a sterile dental mouth mirror and Periodontal probe (Hu Friedy, Chicago, IL, USA). The presence of plaque was recorded using the plaque index (PI)[19] and the gingival condition using the gingival index (GI).[1920] The clinical attachment level (CAL) and the probing depth (PD) were measured at six sites per tooth. The frequency of missing teeth was also reported. All clinical data were collected by a single examiner, who had been calibrated prior to the commencement of the study until the examiner could maintain >90% agreement on repeated measures of all examination protocols. The intra-examiner agreements were evaluated by means of repeated measurements with a 7-day interval from the first examination.

Statistical analysis

The mean values for the PI, the GI, the PD, the CAL, and the frequency of missing teeth were calculated for each subject and compared for each group. Nonparametric test (Chi-square test, Fisher's exact test and Mann–Whitney test), and parametric test (unpaired t-test) were used to compare different variables used in this study. Data were stored in a database and was or were analyzed using Statistical Package for Social Sciences (SPSS) for Windows version 16th (SPSS version 16, Chicago, Illinois).

RESULTS

Initially, 66 subjects according to the inclusion criteria were recruited for the study. After SCID 6 subjects were excluded from the study because four subjects refused the periodontal examinations and two of them showed the bipolar disorder. The final sample size was comprised of 60 subjects (30 MDD outpatients and 30 healthy controls). Clinical periodontal examination and psychiatric interview were done for these subjects.

Table 1 shows the demographic and socioeconomic data of 60 subjects. Employment status (P < 0.001) and household income (P = 0.006) between groups were statistically significant. About 56.67% subjects in the case group were unemployed whereas only 6.67% subjects in the control group were unemployed. Household income of 96.67% subjects in the case group and 63.33% subjects in the control group were less than Rs. 6000/month. Table 2 shows the mean scores of clinical parameters between the groups. There was a statistically significant difference between groups in all clinical parameters evaluated (P < 0.05). The PI, the GI and the frequency of missing teeth were 1.56 ± 0.5, 1.82 ± 0.65, and 2.3 ± 1.6 for case group and 1.12 ± 0.38, 1.14 ± 0.81, and 1.13 ± 1.28 for control group, respectively. The mean probing pocket depth was 4.67 ± 0.8 mm for the case group and 2.6 ± 2.2 mm for control group whereas mean CAL for case was 4.96 ± 0.2 mm and for control was 2.7 ± 0.43 mm. Table 3 represents MDD and Hamilton scores. About 83.33% subjects under case group had more than one episodes of depression. Most of depression had melancholic features (86.67%) and about 76.67% were classified as severe. The HAM-D-31 mean values were statistically significant. [Table 4] shows the statistically significant mean scores of probing pocket depth, CAL and missing teeth between smokers and nonsmokers (P < 0.05).

Table 1

Demographic and socioeconomic variables of the groups

Table 2

Clinical parameters in case and control groups (mean±SD)

Table 3

Depression characteristics of the groups

Table 4

Periodontal clinical characteristics of the nonsmoking and smoking groups

DISCUSSION

The connection between the body and mind is a topic of much controversy. For many years studies have been performed to show the relationship between psychosocial factors and periodontal status. This study is one of them in order to show an association between depression and periodontitis. For this study, we selected MDD patients because psychoneuroimmunology studies have shown that immunological and endocrinological alterations in patients with MDD differ from those of subjects with posttraumatic stress disorder, personality disorder and/or a history of early adverse stressful events.[1621] We used observer rating scale (HAM-D-31) and a diagnostic instrument (structured clinical interview) for psychiatric evaluation because self-report scales do not allow an assessment of the subjective and behavioral aspects of individuals and when this type of instrument is used in research, one should bear in mind that the informers may supply incorrect information due to misunderstanding of the questions. Structured clinical interview is the gold standard for classification of major psychiatric and personality disorders. In this study, patients with periodontitis showed significantly higher observer-rated score, similar results were observed in the study performed by Saletu et al.[4]

Subjects with MDD and control group had a similar distribution for most of the demographic and clinical variables such as age, gender, educational level, marital status, and smoking status. Socioeconomic level is a good marker of various risk factors for periodontitis such as oral hygiene, provision of dental care, and behaviors. Previous studies have documented differences in periodontal health based on socioeconomic status (SES) factors, such as income and education, showing that lower SES was associated with increased risk to periodontitis.[22] In this study, patients with depression had a lower household income, probably because of the larger number of unemployed individuals (56.67%) in this group. This finding is consistent with studies that have shown a higher prevalence of depression among unemployed compared to employed individuals and can be explained by the debilitating nature of MDD.[23] This shows that unemployed status and low household income were prime risk factors for MDD, which affected behavioral and neuroendocrinological changes that leads to severe clinical attachment loss and PD. In our study, greater proportion of females, among depression patients with the female/male ratio of about 2:1, is found which suggests higher prevalence of MDD in females, this is in accordance with an epidemiological study conducted by Bromet et al.[24]

In this study, the amount of plaque was significantly higher in cases compared with control (P = 0.001). The patients had a statistically significant mean GI when compared to that of controls (P < 0.001), this is in accordance with studies conducted by Genco et al.,[25] and Ng and Leung.[26] Our study showed a statistically significant association between periodontal clinical parameters like mean PD and CAL between the case group and the control group, respectively (P < 0.05). This high level of clinical attachment loss and PD may be due to fact that depression enhances the production of pro-inflammatory cytokines, including Interleukin (IL)-6.[12] In a more extensive study, Alesci and colleagues found that IL-6 levels were increased in MDD patients throughout the circadian cycle. There was a 12 h shift in the circadian rhythm of IL-6 plasma levels and its complexity was reduced.[27] Johannsen et al.,[28] compared oral health status, proinflammatory markers, and cortisol in gingival crevicular fluid (GCF) and saliva in patients with stress-related mental depression and controls to investigate the importance of stress for the development of periodontitis. They found that the levels of cortisol and IL-6 in GCF were significantly higher in patients than in controls. Significantly, both depressive symptoms and syndromal depression are associated with heightened plasma IL-6 levels. Overproduction of proinflammatory cytokines may lead to maladaptive immune and endocrine changes subsequently. IL-6 is a potent stimulator of corticotrophin releasing hormone production, a mechanism that leads to heightened HPA activity, including elevated levels of plasma adrenocorticotropic hormone (ACTH), followed by increased cortisol levels:[29] Elevation in ACTH and cortisol can provoke multiple adverse immunological changes.

Our study indicated an adverse effect of MDD on oral hygiene. The depressed patients had significantly higher plaque accumulation (P = 0.001) and gingival inflammation (P < 0.001), this was in agreement with the findings of Johanssen et al.,[30] The depressed patients neglect oral hygiene and professional regular dental care due to reduced motivation and interest.[31] In this study, significant relationship was found between smoking, CAL (P = 0.001), probing pocket depth (P = 0.002), and missing teeth (P < 0.001) This was in accordance to longitudinal study conducted by Jasmin M Albandar et al.,[32] Our study consisted of equal distribution of smokers between MDD patients and controls, and there was no significant difference of Gl and PI between smokers and nonsmokers. Many studies have found that GI is lower in smokers[3334] and smoking is more prevalent in depression patients.[3536]

Discrepancies in results between our study and others may be due to differences in the controlled variables: Depression level, sampling strategies, study design and age range. Various studies used self-report scales as instruments to measure psychological variables. These differences may limit the comparisons between the investigations. Discrepancies in the results found in the literature may also be explained by differences in sample sizes of the studies. We recognize the limitations of the small, homogeneous sample that limited the generalizability, and power to detect some associations.

CONCLUSION

The results of our study suggest that MDD may influence periodontal disease due to its impact on psychoneuroimmunology, endocrinology and also on human behavior. Hence, it is important to understand patients’ physical and psychological state both to help in maintaining a healthy periodontium. Further studies are required to investigate the association of periodontal disease and MDD using structured interviews on groups with operational diagnosis, by means of instruments like DSM-IV. Thus, sources of error can be minimized and the influence of depression on periodontal status can be evaluated with greater precision.