Factors Affecting Clinical Depression in Diabetic Geriatric Population

Introduction: Diabetes mellitus is a common metabolic disorder affecting about 10% 25% of the elderly population. The mechanisms, linking diabetes and major depressive disorders are unknown. Obesity is the risk factor for both diabetes mellitus and depression. The goal of this study was to explore if BMI of elderly diabetic patients with depression differed from BMI of the diabetic individuals without depression. Further, we aimed to explore the association of age, gender, health insurance status, ethnicity influence and systolic blood pressure (SBP) and diastolic blood pressure (DBP) with clinical depression in geriatric diabetics. Methods: Nursing home residents were recruited from an outpatient internal medicine clinic in a teaching university setting. After given written consent, patients received Public Health Questionnaire-9 (PHQ-9) in either English or Spanish language. Results: While the clinically depressed diabetic participants did not differ from that of the non-depressed diabetic participants with respect to age (70.6 ± 6.1 vs. 72.1 ± 4.8; p = 0.111), gender (47.2% of males vs. 57.1% of females; p = 0.754), or ethnicity (69% explain vs. 71%, p = 1.000), race did appear to differ in depression status: Caucasian, African-American, and others were respectively 37%, 48%, and 15% vs. 32%, 16%, 52%, p = 0.0003). Neither the BMI (p > 0.499) nor Hemoglobin A1c (p > 0.839) differed between the clinically depressed and non-depressed participants when controlled for these race differences. Conclusion: In our sample, diabetic African Americans are three times more likely to be depressed. Diabetic Caucasians also experience higher rates of clinical depression. However, diabetics with depression did not differ from diabetics without depression with regard to their age, gender, BMI, HbA1C, health insurance status, systolic blood pressure or diastolic blood pressure.


Introduction
Diabetes mellitus-a common metabolic disorder affecting about 10% -25% of the elderly population [1] is frequently associated with psychiatric disturbances [2].Patients with diabetes mellitus are 2 -4 times more likely to be diagnosed with major depressive disorder [3].In elderly diabetic patients the risk of depressive mood symptoms is increased by 30 % (HR 1.31 (95% CI: 1.07 -1.61)) [4].The adjusted odds ratio (OR) for functional disability is 7.9 per subject with diabetes and depression, whereas OR is 2.4 for subjects with diabetes alone and three for subjects who have major depression alone [5].The mechanisms, linking diabetes and major depressive disorders are unknown.Obesity is the risk factor for both diabetes mellitus and depression.However, data-exploring association of body mass index (BMI) in diabetic patients, suffering from depression, is sparse.
Background: people with diabetes have an increased risk of developing depressive symptoms and people with depression also have an increased risk of developing diabetes [6].It is estimated that about one third of diabetics suffer from clinical depression [3] [6].The prognosis of both diabetes and depression in terms of severity of disease, complications, treatment resistance and mortality is worse for either diseases when they are comorbid than when they occur separately [6] [7].Besides clinical depression, diabetes mellitus has also been an established risk factor for cardiovascular diseases [8], metabolic syndrome, stroke, retinopathy and obesity [9] [10].
However, the epidemiological data-linking diabetes with such risk factors, including obesity, smoking, and perceived burden of diabetes treatment, particularly in the genetic population, remains sparse.
A number of studies have reported prevalence rates of depression markedly and inconsistently high in people with type II diabetes compared to those without type II diabetes [11] [12].Such rates have varied between 17.8% and 39%.However, certain European and Canadian studies have reported lower prevalence rates of depression in people with type II diabetes [13] [14].Other studies, including that of Holt et al. (2009), have reported lower rates of depression in both people with and without type II diabetes (5% versus 3.8%) but they find a statistically significant association between depression and diabetes.Icks et al. [15] have suggested that there is no significant association between diabetes and depressive symptoms in women after controlling for comorbidities.For diabetes mellitus type I, the prevalence of clinical depression and controlled studies was 12% (5.8% -43.3%) for people with diabetes compared with 3.2% (2.7% -11.4%) for control subjects [16].In contrast, other studies [17] reported significant high prevalence rates of depressive symptoms in both men and women with type I diabetes compared to individuals without diabetes (men: 25.5 versus 11.6%; women:37.9versus 20.5%).Through a more recent cross-sectional study involving out-patients with diabetes in the Netherlands, it was observed that about one third of the sample reported elevated depression scores, and that eight-24% were diagnosed with a depressive disorder [10].
Most studies considering race or ethnicity only analyzed ethnicity as an associate variable of depression and/or diabetes.Studies with African-American participants have shown a mixed picture in terms of rates of diabetes and depression [12] [18].Katon et al. [19] reported that depressed individuals were less likely to be African-American, and were more likely to be Hispanic (African-American 13%; Asian American 15.2%; white Americans 15.5%; Hispanic 21.8%).However, Lin et al. [20] found no difference in rates between White Americans and non-White Americans for either minor depression of a major depression.European studies have reported higher levels of depressive symptoms or depressive effects in non-Dutch patients with type II diabetes compared with Dutch patients.However, they found no ethnic differences in depression in patients with type I diabetes [10].Ali et al. [11] have found that the United Kingdom reports lower levels of diagnosed depressive disorder than their White European counterparts.
A number of studies have found diabetic women to have higher rates of depression than their men counterparts with similar findings in type I diabetes mellitus and type II diabetes mellitus [16] [21] [20].However, Holt et al. [22] found diabetic men to have more depression rates than diabetic women.
In regards to age, a number of community-based studies in the US have reported an increase prevalence of psychological morbidity in younger adults with type II diabetes.Most studies have reported age as a risk factor for depression.However, depression has been found to be less common in older cohorts would depression [23].Collins et al. [9] have reported lower rates of depression in older individuals with type I diabetes mellitus, suggesting that age may have a protective effect.
The goal of this study was to explore if BMI of elderly patients with diabetes differed from BMI of the individuals without depression.Further, we aimed to explore the association of age, gender, health insurance status, ethnicity influence and systolic blood pressure (SBP) and diastolic blood pressure (DBP) with clinical depression in geriatric diabetics.

Study Design
This was a cross-sectional analytic comparative non-interventional study.

Subjects' Recruitment and Characteristics
Nursing home residents were recruited from outpatient internal medicine clinics at the Texas Tech Health Science Center at Permian Basin between 2012 and 2013.All consenting diabetics with duration of diagnoses more than one year, irrespective of type I or type II over the age of 65 were eligible for the study.Relevant information was collected including independent variables: age, gender, ethnicity, Systolic and Diastolic blood pressure, BMI and latest HbA1c.The dependent variable was assessed with Patients received Public Health Questionnaire-9 (PHQ-9) in either English or Spanish language.The PHQ is based on DSM-IV (Diagnostic and statistical Manual -IV) criteria and has a 88% sensitivity and 88% specificity for diagnosis of major depression (PHQ score ≥ 10) in comparison to interview by mental health professionals.

Statistical Method
Univariate analysis was conducted to compare depressed and non-depressed nursing home residents with respect to the primary outcome measures of BMI and HgA1c along with secondary outcomes of SBP and DBP.In the absence of any statistical significance (alpha = 0.05) between primary outcomes of the two groups, the age, race, ethnicity, gender, and insurance status between groups were compared in a similar fashion to probe for confounding.A post-hoc analysis was conducted comparing HgA1c and BMI between the depressed and non-depressed groups after adjusting for significant race differences between the two groups.

Discussion
In our sample, diabetic African Americans are three times more likely to be depressed.Diabetic Caucasians also experience higher rates of clinical depression.However, diabetics with depression did not differ from diabetics without depression with regards to their age, gender, BMI, HbA1C, health insurance status, systolic blood pressure or diastolic blood pressure.
Diabetes is a risk factor for high prevalence of depression [24].It is possible that stress-associated hypothamamic-pituitary adrenal axis reaction with lowered hippocampal volume, upregulation of serotonin receptors (5 HT-2A receptors), decreased BDNF (Brain Derived Neurotropic Factor) and elevated inflammatory cytokines in diabetes may be directly related to the depression in diabetes.Our findings are in agreement with data, reporting higher incidence of depression in African American patients with diabetes [25] [26].However, unlike the previous studies [27] [28], presence of clinical depression did not influence HbA1C levels.Similar to Munshi et al. [29], Engum [30] and Lin et al. [20] we did not find an association between the presence of depression and glycemic control.Knol et al. [8] in the cross-sectional study also demonstrated that impaired fasting glucose was not associated with depression in people with diabetes.Only one longitudinal study observed a significant association between elevated mean HbA1c values and a history of depression among participants with diabetes [31].In a more recent cross-sectional study involving outpatients with any form of diabetes, Pouwer et al. [32] found that   depressive effect was associated with poor glycemic control for type 1 DM only.
Depressed diabetic patients in our study did not differ in their BMI compared to non-depressed diabetic participants.This is contrast to other studies [33] who found increased BMI in the patients with diabetes and depression.
The gender has been reported to play an important role in the psychiatric disorders.Women with diabetes have consistently shown higher rates of depression than men [9] [31] [34] [35].However, in our study we did not find any gender difference in diabetic patients with or without clinical depression.Our results are in line with the findings of one study [36] where, when controlled for BMI, age, race, there was no gender difference in presence of clinical depression, in diabetic patients Age is associated with the clinical symptoms of depression.Studies found that younger patients with diabetic tend to experience more clinical depression than elderly population with diabetes [7] [20] [23].In fact, Collins et al. [9] have reported lower rates of depression in older individuals, suggesting that age might be a protective factor.
It has been argued that diabetes precedes depression and leads to depression either through a direct effect of hyper glycaemia, possibly leading to altered glucose transport in the brain, or as a result of the psychological stress resulting from the knowledge of the diagnosis or from the rigorour treatment, throught the both-lifestyle corrections and pharmacological interventions [3] [30] [37].However, this assumption has been challenged by several recent cohort studies that have suggested that depression may be a risk factor for diabetes [30] [12] [36] while diabetes does not necessarily predict depression or is associated with only a modest risk of development of depression [30].
There are a number of limitations of this study.The design of the study gives only a snap shot of the symptoms experiencing by the participants in the previous two weeks.A prospective case controlled study would have been informative.We took one-year duration of diabetes as a cut off point for inclusion in this study.Hence this study does not provide information about effect of new onset of diabetes on mood symptoms.We also did not take into consideration if the diabetics had any comorbid complications of diabetes such as diabetic retinopathy or neuropathy, which can cause severe limitations and hence influence mood symptoms.Most importantly, we had assessment of depressive symptoms through one time evaluation through PHQ-9 in lieu of a comprehensive clinical depression assessment.However in spite of the limitations as this is first study in our knowledge that has tried to assess the effect of such confounding factors (age, gender, ethnicity, race, health insurance status, SBP/DBP, BMI and HbA1c) on development of depression in geriatric population.
Future studies may need further exploration of the association of such factors in a prospective case controlled design.

Conclusion
In summary, despite being cross-sectional, our study is significant for its unexpected findings.

Addendum
CRI contributed to the collection and analysis of the data.

Figure 1 .
Figure 1.Difference between mean hemoglobin A1c levels between depressed and non-depressed diabetics.

Table 1 .
Association of confounding factors (BM1, age, ethnicity, gender, race and health insurance status) for depressed and non-depressed diabetics.

Table 2 .
Showing outcome measures for Hemoglobin A1c (HA1c), Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) for diabetics with and without depressive symptoms.