Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest. The American Psychiatric Association’s Diagnostic Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) classifies the depressive disorders into:
- Disruptive mood dysregulation disorder
- Major depressive disorder
- Persistent depressive disorder (dysthymia)
- Premenstrual dysphoric disorder
- Depressive disorder due to another medical condition
The common features of all the depressive disorders are sadness, emptiness, or irritable mood, accompanied by somatic and cognitive changes that significantly affect the individual’s capacity to function.
Because of false perceptions, nearly 60% of people with depression do not seek medical help. Many feel that the stigma of a mental health disorder is not acceptable in society and may hinder both personal and professional life. There is good evidence indicating that most antidepressants do work but the individual response to treatment may vary.
The etiology of major depressive disorder is multifactorial with both genetic and environmental factors playing a role. First-degree relatives of depressed individuals are about 3 times as likely to develop depression as the general population; however, depression can occur in people without family histories of depression.
Some evidence suggests that genetic factors play a lesser role in late-onset depression than in early-onset depression. There are potential biological risk factors that have been identified for depression in the elderly. Neurodegenerative diseases (especially Alzheimer disease and Parkinson disease), stroke, multiple sclerosis, seizure disorders, cancer, macular degeneration, and chronic pain have been associated with higher rates of depression. Life events and hassles operate as triggers for the development of depression. Traumatic events such as the death or loss of a loved one, lack or reduced social support, caregiver burden, financial problems, interpersonal difficulties, and conflicts are examples of stressors that can trigger depression.
Twelve-month prevalence of major depressive disorder is approximately 7%, with marked differences by age group. The prevalence in 18- to 29-year-old individuals is threefold higher than the prevalence in individuals aged 60 years or older. Females experience 1.5- to 3-fold higher rates than males beginning in early adolescence. In the US, depression affects nearly 17 million adults but these numbers are gross underestimates as many have not even come to medical attention.
The underlying pathophysiology of major depressive disorder has not been clearly defined. Current evidence points to a complex interaction between neurotransmitter availability and receptor regulation and sensitivity underlying the affective symptoms.
Clinical and preclinical trials suggest a disturbance in central nervous system serotonin (5-HT) activity as an important factor. Other neurotransmitters implicated include norepinephrine (NE), dopamine (DA), glutamate, and brain-derived neurotrophic factor (BDNF).
The role of CNS 5-HT activity in the pathophysiology of major depressive disorder is suggested by the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs). Research findings imply a role for neuronal receptor regulation, intracellular signaling, and gene expression over time, in addition to enhanced neurotransmitter availability.
Seasonal affective disorder is a form of major depressive disorder that typically arises during the fall and winter and resolves during the spring and summer. Studies suggest that seasonal affective disorder is also mediated by alterations in CNS levels of 5-HT and appears to be triggered by alterations in circadian rhythm and sunlight exposure.
Vascular lesions may contribute to depression by disrupting the neural networks involved in emotion regulation—in particular, frontostriatal pathways that link the dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate, and dorsal cingulate. Other components of limbic circuitry, in particular, the hippocampus and amygdala, have been implicated in depression.
History and Physical
The investigation into depressive symptoms begins with inquiries of the neurovegetative symptoms which include changes in sleeping patterns, appetite, and energy levels. Positive responses should elicit further questioning focused on evaluating for the presence of the symptoms which are diagnostic of major depression. These are the 9 symptoms listed in the DSM-5. Five must be present to make the diagnosis (one of the symptoms should be depressed mood or loss of interest or pleasure):
- Sleep disturbance
- Interest/pleasure reduction
- Guilt feelings or thoughts of worthlessness
- Energy changes/fatigue
- Concentration/attention impairment
- Appetite/weight changes
- Psychomotor disturbances
- Suicidal thoughts
- Depressed mood
All patients with depression should be evaluated for suicidal risk. Any suicide risk must be given prompt attention which could include hospitalization or close and frequent monitoring.
Other areas of investigation include:
- Past medical history and family medical history, and current medications
- Social history with a focus on stressors and the use of drugs and alcohol
- History and physical examination to rule out organic causes of depression. Depressive symptoms and their severity are also evaluated with the help of questionnaires such as the Beck's Depression Inventory (BDI), Hamilton Depression Scale (Ham-D), and Zung Self Rating Depression Scale
The diagnosis of depression is based on history and physical findings. No diagnostic laboratory tests are available to diagnose major depressive disorder. Laboratory studies are, however, useful to exclude medical illnesses that may present as major depressive disorder. These laboratory studies might include the following:
- Complete blood cell (CBC) count
- Thyroid-stimulating hormone (TSH)
- Vitamin B-12
- Rapid plasma reagin (RPR)
- HIV test
- Electrolytes, including calcium, phosphate, and magnesium levels
- Blood urea nitrogen (BUN) and creatinine
- Liver function tests (LFTs)
- Blood alcohol level
- Blood and urine toxicology screen
- Arterial blood gas (ABG)
- Dexamethasone suppression test (Cushing disease, but also positive in depression)
- Cosyntropin (ACTH) stimulation test (Addison disease)
- Computed tomography (CT) scanning or magnetic resonance imaging (MRI) of the brain should be considered if organic brain syndrome or hypopituitarism is included in the differential diagnosis
- Illness anxiety disorders
- Schizoaffective disorders
- Somatic symptom disorders
Major depression has very high morbidity and mortality contributing to high rates of suicide. Even though effective drug treatment is available, nearly 50% may not initially respond. Complete remission is not common but at least 40% achieve partial remission in 12 months.
However, relapses are common and many patients require a variety of treatments to control the symptoms. The quality of life of most patients with depression is poor.
Depression accounts for nearly 40,000 cases of suicide each year in the US. The highest rate of suicides is in older men.
Enhancing Healthcare Team Outcomes
Depression is a very common disorder encountered by the nurse practitioner, primary care provider, psychiatrist, and mental health worker, coordinating as an interprofessional healthcare team. The disorder has extremely high morbidity including the risk of suicide. All healthcare workers should be knowledgeable about this disorder and refer the patient to a psychiatrist if there is a risk of self-harm.
Education plays an important role in the successful treatment of major depressive disorder. This would include the education of the family and the patient. Lack of accurate information and misperceptions of the illness as a personal weakness or failings leads to painful stigmatization and avoidance of the diagnosis by many of those affected. Patients should know the rationale behind the choice of treatment, potential adverse effects, and expected results.
The involvement of the pharmacist in the treatment plan can enhance medication compliance and referral for psychotherapy. The pharmacist can also check that dosing is appropriate, that there are no significant interactions, and counsel on adverse effects. Engaging family members can be a critical component of a treatment plan. Family members are helpful informants, can ensure medication compliance, be a big source of social support and can encourage patients to change behaviors that perpetuate depression (e.g., inactivity).
Patients with moderate to severe depression should also be seen by a social worker or case management nurse to ensure that they have a support system and finances for treatment. If there is a concern, the person managing the case should present the issues to the interprofessional team so that a plan can be developed to get the patient the care they need. Overall, depression is managed by an interprofessional team dedicated to the management of mental health disorders. Open communication between all the members of the interprofessional team is the key to lowering the morbidity of the disorder. [Leve 5]
The outcomes for patients with depression are guarded. There is no cure and the condition has frequent relapses and remissions, leading to a poor quality of life.