INTRODUCTION

Depression is a public health issue of global proportions. It is anticipated that some 300 million people worldwide suffer from depression (Commonwealth Department of Health and Aged Care, 2001). Depression is associated with significant distress for individual sufferers and their families, and can lead to impairment in educational, social, family and employment functioning and outcomes. As would be expected for a common and serious illness, a significant proportion of health expenditure in Australia is devoted to the treatment of depression. Approximately 24% of service contacts with public-sector community mental health services relate to mood disorders, and there are approximately 22,170 admissions to public hospitals and 11,870 admissions to private hospitals for mood disorders each year (Australian Institute of Health and Wellbeing, 2006). The direct cost of treating depression each year is estimated to be in excess of $600 million. The true cost of depression for the community, which includes the indirect costs associated with the reduced productivity that accrues from a disabling condition, defies quantification. In Australia depression has been identified as a National Health Priority Area in an attempt to elevate depression to the same level of community consciousness and coordinated health policy response—in the form of prevention, assessment and treatment—as heart disease, diabetes and cancer (Commonwealth Department of Health and Aged Care, 2001).

Nurses working in a variety of settings are well placed to be able to play a role in the identification, assessment and management of depression. The fact that depression is disconcertingly prevalent means that nurses working in acute hospital, community, primary and aged care contexts will encounter individuals with clinically significant depression, and may be the first clinician to directly explore the likelihood of depression. Early identification and mobilisation of effective treatment responses is the single most likely means by which the disability of burden of depression for individuals, their families and carers and the community can be reduced. Treatment for depression can be highly effective, potentially reducing the distress of depression and its disabling impact on occupational, social, family and relationship functioning. It remains a grim reality that each year upwards of 2300 Australians choose to end their lives by suicide, many or most of whom have been depressed or suffering from another mental disorder at the time of their death (Australian Institute of Health and Wellbeing, 2006). This is a statistic that underscores the importance and potential of nurses, and clinicians from varying disciplines, to have an understanding of the epidemiology, clinical features, assessment, treatment and management of the depressive disorders.

THE SCOPE OF THE PROBLEM: THE EPIDEMIOLOGY OF DEPRESSION

Over the past two to three decades there has been significant research interest in identifying and understanding the epidemiology of depression (and mood disorders). This activity has, in large part, been driven by improved methodological approaches (e.g. the use of standardised diagnostic interviews) for undertaking large-scale community surveys to assess incidence and prevalence at a population level. Population-based surveys of the prevalence of depression—undertaken as part of larger studies of the epidemiology of mental disorders—have been conducted and reported in the United States (Regier & Robins, 1991; Weissman et al, 1988; Kessler et al, 1994), New Zealand (Wells et al, 1989), Britain (Jenkins et al, 1997) and Australia (Australian Bureau of Statistics, 1998; Andrews et al, 2001).

Early findings of the community prevalence of depression arose from the Epidemiological Catchment Area Study, in which a standardised diagnostic interview was undertaken with some 20,000 participants in the United States. Approximately one-third of participants reported periods of dysphoria of at least two weeks’ duration at some point in their lifetime. The study estimated that 6.3% of the US population aged 18 years or over had experienced at least one clinically significant episode of depression (major depressive episode) during their lifetime (Regier & Robins, 1991). A second large-scale study, the National Co-morbidity Study, used a different survey instrument and identified the lifetime rate of major depressive episode to be 17.1% among the adult population (12.7% for adult males, and 21.3% for adult females (Kessler et al, 1994).

In the Australian National Survey of Mental Health and Wellbeing a sample of approximately 778,000 adults were interviewed with a standardised diagnostic instrument (the Composite International Diagnostic Interview), which identified that in the 12-month period prior to interview 5.8% of the adult population had experienced an identifiable and clinically significant depressive disorder (major depressive episode) (Australian Bureau of Statistics, 1998). A separate child and adolescent component of the study identified that 3% of children and young people (6–17 years) experienced a depressive disorder in the 12-month period preceding the survey (Sawyer et al, 2001).

The differences in reported lifetime rates of major depression between studies are likely to be attributable to two factors: methodological variance and/or recall bias. Some variance may be accounted for by the different methodological approaches between studies, for example the diagnostic interview instrument employed. Also, there is the possibility that participants’ ability to accurately recall having experienced episodes of depression across their lifetime may play a role in explaining the reported difference in prevalence rates (Andrews et al, 1999). Considering data from multiple studies, Wilhelm et al (2003) have identified in a survey which asked participants to rate depressive symptoms in previous one-month period that the current prevalence of major depression among adults aged 18 years or over is between 3% and 5%.

A consistent finding across studies of the epidemiology of depression is a strong female preponderance, with most studies identifying up to a twofold increase in prevalence among women (Kuehner, 2003). The causes of this apparent gender difference have been the focus of significant research interest. It has been proposed that the gender ‘difference’ may be an artefactual finding, possibly reflecting that women are more likely to recall episodes of depression over their lifetime than men, or that women might be more likely to reflect on or amplify their mood states than men, who employ distraction or denial as means of coping with dysphoria (Parker and Brotchie (2004)). Differential exposure and vulnerability to social or environmental stressors, for example sexual violence, has also been suggested, although not consistently demonstrated in research. Kessler and McLeod (1984) proposed a ‘cost of caring hypothesis’, suggesting that female gender roles around caring could increase women’s exposure and sensitivity to life events in their social networks. Biological difference has also been considered, with pubescent changes in hormones being a focus of interest, given that the female preponderance for depression commences between the ages of 15 and 18 (Arnold et al, 1998). Parker and Brotchie (2004) have hypothesised that, since the female preponderance for depression also extends to anxiety, there may be a post-pubertal effect of sex hormones on limbic system hyperactivity that increases risk of both depressive and anxiety disorders.

IDENTIFYING THE DISABILITY IMPACTS OF DEPRESSION

In 1996, the World Health Organization (WHO) and the World Bank commissioned the Global Burden of Disease study (Murray & Lopez, 1996). The study represented the most comprehensive attempt to quantify and explicate the mortality and disability impacts (burden of disease) of all diseases, injuries and risk factors using robust methodological approaches. Disability was estimated by using the Disability Adjusted Life Year (DALY) measure, which expresses the years of life lost due to premature death and years lived with a disabling illness of specified duration and severity (Joyce & Mitchell, 2004). Mental illness contributed a significant proportion of DALY-measured disability, with ‘uni-polar major depression’ estimated by 2020 to contribute the second largest share of disability worldwide (Murray & Lopez, 1997a, 1997b).

In the Australian context, mental disorders are estimated to account for 13% of the total burden of disease, measured using DALYs. In females, anxiety and depression are the leading cause of disease burden (10% of total burden), while in males anxiety and depression are the third leading cause of disease burden after ischaemic heart disease and type 2 diabetes (4.8% of total burden) (Begg et al, 2007).

CLINICAL FEATURES OF DEPRESSION AND ASSESSMENT APPROACHES

Depressed, sad or dysphoric mood is a common and normal response to life’s challenges and vicissitudes. There would be few people who could not relate to the experience of having felt sad in response to a loss of some kind; this level of normal range of emotion and emotional reactivity does not in and of itself constitute ‘clinical’ depression. Distinguishing circumstances where depressed mood is indicative of a depressive disorder requiring definitive treatment, as against an understandable and transient feeling state, is a key challenge for clinicians working in a variety of clinical settings.

Major (clinical) depression is distinguished from what might be understood to be ‘normal’ depression on the basis of the presence of certain symptoms, and the severity, duration and persistence of these symptoms. There is no single or pathognomonic symptom that is necessary or sufficient for the diagnosis of major depression. Although pervasive feelings of lowered mood or sadness are frequent features of major depression, it is not clear that depressed mood per se is the core pathological change. It has been suggested that mood disturbance may be an epiphenomena of a syndrome of core deficits in relation to energy, motivation and activation. This possibility is suggested by the fact that some individuals who report depressive symptoms of reduced energy and motivation, poor concentration, inability to feel pleasure, reduced appetite and sleep problems do not report feeling sad or depressed in their mood (Joyce 2004).

There are two widely used international diagnostic classification systems for mental disorders: the Diagnostic and Statistical Manual of Mental Disorders (4th edn) (DSM-IV) published by the American Psychiatric Association (American Psychiatric Association, 2000), and the International Classification of Diseases (10th edn) (ICD 10), published by WHO (1992). Both systems identify operationalised diagnostic criteria for each of the mental disorders, including depression and other disorders of mood.

For a diagnosis of major depressive episode to be made, DSM-IV requires the presence of at least a two-week period of depressed mood or loss of interest or pleasure in most activities. The depressed mood or loss of interest and pleasure must be present for much of nearly every day, on the basis of an individual’s self-report or the observation of others. In children the predominant mood state can be one of irritability. In addition at least four of the following behavioural, biological, psychomotor or psychological symptoms must be present:

The average age of onset of a first episode of depression is in the late 20s. Depression can, however, occur at any age. Both childhood and late-life depression are relatively common, and are sometimes under-recognised by health professionals (Bostic et al, 2005).

In children depression can sometimes present quite differently from adults. Depressed preschool children may display behavioural problems, apathy, withdrawal, irritability, regression or complain of somatic concerns such as headache or stomach aches. School-aged children may display crying spells, sadness or irritability and complain of somatic problems (Martin, 2004; Bostic et al, 2005).

Depression in older people has been estimated to occur at a rate of approximately 2–5%, while in residential aged care settings such as hostels or nursing homes the rate is estimated to be much higher, at 6–18%. In older people one of the key challenges from an assessment point of view is disentangling and distinguishing symptoms of depression from symptoms related to grief and loss, dementia, Parkinson’s or other medical disease, or the effects of prescribed medication (Australian Bureau of Statistics, 1998; Byrne, 2004).

CHRONICITY AND DEPRESSION

The duration of an episode of major depression is variable, lasting from weeks to years in some cases. Left untreated, and assuming that a person has been kept safe, major depression can remit of its own accord in six to nine months (American Psychiatric Association, 2002). The likelihood of recurrence after an episode of treated depression is approximately 40% within one year. Studies that have assessed long-term outcome at 25 years following an index episode have found high rates of persisting symptoms or recurrence (Brodaty et al, 2001; RANZCP Clinical Practice Guidelines Team for Depression, 2004).

Taken together these findings underscore the potential level of disability that can accrue from recurrent episodes of major depression (major depressive disorder). Depression can contribute chronicity and disability in other circumstances: where a dysthymic disorder (a low-grade and chronic form of depression) is present; where full remission of symptoms in response to adequate treatment is elusive (treatment resistance); or where symptoms are persistent in nature (chronic depression).

MAPPING THE TERRAIN: SOME ISSUES IN SUBTYPING AND CLASSIFYING DEPRESSIVE DISORDERS

Depression is a term used to describe states of mood that are part and parcel of human experience, being felt by nearly everyone at times of, say, grief, loss or life stress. Depression is also understood to refer to a serious and, in some cases, life-threatening illness that requires clinical assessment and treatment. At face value it is tempting to assume a link between feeling states that are commonplace but generally transient and what is understood to be ‘clinical’ depression—an essentially single phenomenon that is distinguished by severity and persistence.

The extent to which depression represents a single-dimensional phenomenon, as against a range of discrete disorders with differing symptoms and, by extension, treatment characteristics, has been the focus of close to a century of debate. The identification of meaningful subtypes of depression—either clinically or in research—is a profitable exercise if subtypes are associated with differential response to treatment. In a clinical setting, for example, being able to identify the circumstances under which a psychological versus a biological treatment approach would be most appropriate, or being able to decide with some confidence which of a range of treatments would be most suitable, would have significant utility. Table 13.1 identifies the subtypes of depression that are detailed in the DSM-IV (American Psychiatric Association, 2000).

Table 13.1 Severity and sub-types of depression.

SEVERITY OF MAJOR DEPRESSION (MD)
EPISODES CAN BE CLASSIFIED AS MILD, MODERATE OR SEVERE
Mild	• Just meets or slightly exceeds minimum required diagnostic criteria in DSM-IV Only gold members can continue reading. Log In or Register to continue Share this: Click to share on Twitter (Opens in new window) Click to share on Facebook (Opens in new window) Related Related posts: Stigmatisation of people living with a chronic illness and/or disability Advanced dementia Chronic diseases of the bowel Principles of practice for supportive care: diabetes Stay updated, free articles. Join our Telegram channel Join Tags: Chronic Illness and Disability Mar 13, 2017 | Posted by admin in NURSING | Comments Off on Depression: its scope, impacts, treatment and nursing management Full access? Get Clinical Tree Get Clinical Tree app for offline access Get Clinical Tree app for offline access