Identifying Predictors of Functional Limitations Associated with Depression, Anxiety, and Emotional Problems in US Adults

Depressive disorders are characterized as sharing affected mood, and somatic (e.g. sleep pattern, appetite, and unintentional changes in weight) and cognitive alterations from previous normal daily functioning that are clinically significant. Anxiety disorders are characterized by excessive fear, general or specific anxiety, and related behavioral disturbances that are also clinically significant. This project attempts to identify risk factors that may predict what groups are most likely to be affected by depression and/or anxiety. Sponsored by the CDC, the National Health Interview Survey collects general health information for non-institutionalized individuals living in the US. Variables for use in logistic regression model construction were selected from the all-inclusive pool of data measurements taken during the 2014 NHIS person data module, using the literature as a guide. The sample was limited to adult respondents at least 18 years of age. Odds ratios were calculated for each level of potential predictor variables comparing the two levels of the dependent variable: those with a self-reported depression, anxiety, or emotional problem (DAE) related functional limitation and those without. These were used as initial inclusion criteria for logistic regression modeling, which resulted in two final models. Each model contained eight variables accounting for age, marital status, education level, financial factors, and other functional limitations. The nine predictor model also included sex as a predictor (c=0.763), while the eight predictor did not (c=0.790). Different effects were observed in each model. These models were designed for use as a tool for selecting groups for targeted public health intervention, not for use in a clinical setting, and could likely help distinguish groups that would be prime for investigating the prevalence and effects of DAE-related functional limitations. There were several limitations worth addressing in future research into this topic. Identifying Predictors of Functional Limitations Richardson 3 Introduction Not all illnesses are visible. Many conditions are difficult to discern just by looking at a person, but can be managed with medical treatment. But not every illness is so easily managed. Two such illnesses are often very difficult to distinguish and diagnose, even for those living with them. Though highly comorbid, each can independently have an enormous toll on the lives of those they affect. These illnesses are depression and anxiety. Depression as the average person understands it is actually an umbrella term for a group of depressive disorders, each characterized by a distinct but related set of symptoms. For the purposes of this study, these disorders will be collectively explored. The Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) defines depressive disorders as sharing affected mood, as well as somatic and cognitive alterations from previous functioning. These changes all impact daily functioning in a clinically significant manner, which may or may not be worse when observed in conjunction with another chronic condition (Wells et al., 1989). However, depression is a quiet illness. It can go undetected for long periods while still causing difficulties in the daily lives of those affected (APA, 2013a). The symptoms can make basic tasks insurmountable, and can have personal financial repercussions that make this illness a serious issue. Anxiety disorders, as defined by the DSM-5, are characterized by clinically significant, excessive fear, anxiety, and related behavioral disturbances (APA, 2013a). While these first two feelings are connected, they differ in terms of the time frame. Fear is of the present, and anxiety is of the future. Regardless of the specific depressive and anxiety diagnosis from a clinician, there are wellknown issues related to people seeking treatment. Whether due to the stigma associated with mental illness or the common misconceptions surrounding the nature of depressive disorders, many people do not seek treatment. This project will attempt to identify risk factors that may predict what groups are most likely to be affected by depression and/or anxiety. If certain factors can be identified, it may Identifying Predictors of Functional Limitations Richardson 4 ultimately help to reduce the prevalence of untreated depression/anxiety in groups who possess those risk factors by identifying them as high-risk for these illnesses. While this study is entirely retrospective and performed on an existing dataset, the results may help guide future practitioners and public health officials in designing effective interventions targeted at high-risk groups. Background Depression Clinical Understanding of Depression The DSM-5 uniquely characterizes eight depressive disorders. While sharing observable changes from previous functioning, each disorder has unique diagnostic criteria that allow clinicians to specifically diagnose patients suffering with some quantity of depressive symptoms. Each of these depressive disorders can also be characterized by certain features that act to sub-categorize each disorder. It is important to note that this latest revision of the DSM has included a Bereavement Exclusion, indicating a distinction of depressive symptoms from the normal grieving process. Thus, the shared features of each depressive disorder make a collective analysis of depressive symptomology appropriate for data collected in a self-report survey, where those reporting symptoms may not have been formally diagnosed by a clinician. However, these common depressive symptoms can be difficult to distinguish in any individual patient before they have reached a severe level. Mood changes may result in feelings of sadness, irritability, or emptiness, which may become very intrusive into daily functioning. Feelings of guilt are also commonly reported with depressive symptoms, and this guilt is generally unwarranted and overwhelming. Persons living with depression (in any form) also often report significant physical symptoms, including constant achiness, hypersomnia or insomnia, weight gain or loss, concentration issues, and lack of pleasure taken in once pleasurable activities (ADAA, 2015). Identifying Predictors of Functional Limitations Richardson 5 The DSM-5 has not thoroughly characterized the nature of depression. There are many slippery characteristics of this illness that make it difficult to understand, predict, and treat. Some researchers believe that the current framework through which depression is viewed do not capture all persons living with depression (Fried, 2015). While the purpose of this project is not examine the incompleteness of the current understanding of Major Depression, or of depressive disorders on the whole, one must keep in mind that the disease is still misunderstood and not always correctly identified or entirely captured by clinicians. For example, though used as a diagnostic symptom in children and adolescents, the Irritable subtype was not included in the DSM-4 as a diagnostic criterion for adults (Fava et al., 2010). Nor was it included as a possible subset of features or even as a diagnostic criterion in the DSM-5. A thorough examination of the importance of considering irritability as it relates to depression found that irritability was associated with early age at onset of depressive symptoms, lifetime persistence, several comorbidities, and disability due to disease. The study by Fava et al. found that inclusion of irritability as a diagnostic symptom in adults would impact the reported prevalence of the disease, though the significance of this change is debatable. Whatever the ultimate result, Fava et al. certainly indicates that further investigation to determine the validity of irritability as a major part of some depressive diseases might be prudent. Another study, conducted on twins in Sweden, explored irritability and later onset of depressive symptoms. It too found a need for further research into the role of irritable mood in depression, both as a symptom and as an early predictive factor (Savage et al., 2015). Primary care in particular is regularly guilty of addressing all depressive illnesses with a general list of symptoms and treatments. This is part of the spectrum view of depressive disease (Angst, Sellaro, & Merikangas, 2000). Some literature supports this view, while other results support the distinction between subtypes as an important part of clinical treatment. Some support this use of categorical Identifying Predictors of Functional Limitations Richardson 6 diagnosis early in treatment while maintaining the notion that the spectrum approach is more inclusive of depressive disease symptomology (Benazzi, 2006). While this may work in some cases, not enough is understood about the different subtypes and how they are related or not related to make a firm determination of which view is most clinically applicable. There are also note-worthy differences in the diagnostic criteria in the DSM-IV-TR and the DSM5. In the former, depressive disorders were included in the category “Mood Disorders” (SAMHSA/CSAT, 2008). This category also included Bipolar Disorder. These two unique illnesses have since been separated into Depressive Disorders and Bipolar and Related Disorders. The restructuring of clinical diagnostic guidelines speaks to the incomplete nature of the clinical understanding of depression, especially considering the addition of several new depressive disorder classifications to the DSM-5 (APA, 2013b). Prevalence of Depression in the Population From a population based standpoint, Major Depressive Disorder (MDD) is reported by the DSM5 to have a 12-month prevalence of 7%. This is very similar to a report published in 2014 that indicated that 7.6% percent of persons in the US over age 12 had moderate or severe depressive symptoms in the two-week period prior to data collection (Pratt