Depression is a disorder that causes persistent feelings of low mood, low energy and reduced enjoyment of activities. It affects people of all ages and from all backgrounds.
Pathophysiology
The pathophysiology is not fully understood and likely involves a combination of complex mechanisms. At least partially, it appears to involve a disturbance in neurotransmitter activity in the central nervous system, particularly serotonin, also called 5-hydroxytryptamine (5-HT). This makes sense, considering that medications that boost serotonin are effective treatments.
The cause is often described as “a chemical imbalance” or “low levels of serotonin”, which may be helpful as a simple explanation but is probably overly simplistic.
Causes
Depression may be triggered by life events (e.g., the loss of a loved one). However, it can occur without any apparent triggers. It is thought to be caused by genetic, psychological, biological and environmental factors. Having an affected relative is a significant risk factor.
Physical health conditions can trigger or exacerbate depression, and it commonly occurs with conditions such as stroke, myocardial infarction, multiple sclerosis and Parkinson’s disease.
Presentation
The core symptoms of depression are:
- Low mood
- Anhedonia (a lack of pleasure or interest in activities)
Emotional symptoms include:
- Anxiety
- Irritability
- Low self-esteem
- Guilt
- Hopelessness about the future
Cognitive symptoms include:
- Poor concentration
- Slow thoughts
- Poor memory
Physical symptoms include:
- Low energy (tired all the time)
- Abnormal sleep (particularly early morning waking)
- Poor appetite or overeating
- Slow movements
Environmental factors may contribute to the condition, such as:
- Potential triggers (e.g. stress, grief or relationship breakdown)
- Home environment (e.g., housing situation, who they live with and their neighbourhood)
- Relationships with family, friends, partners, colleagues and others
- Work (e.g., work-related stress or unemployment)
- Financial difficulties (e.g., poverty and debt)
- Safeguarding issues (e.g., abuse)
Essential factors to explore when taking a history include:
- Caring responsibilities (e.g., children or vulnerable adults)
- Social support
- Drug use
- Alcohol use
- Forensic history (e.g., violence or abuse)
Every encounter should include a risk assessment for:
- Self-neglect
- Self-harm
- Harm to others (including neglect)
- Suicide
PHQ-9 Questionnaire
PHQ-9 questionnaire is used to assess the severity of depression. There are nine questions about how often the patient is experiencing symptoms in the past two weeks. The higher the score, the more severe the depression:
- 5-9 indicates mild depression
- 10-14 indicates moderate depression
- 15-19 indicates moderately severe depression
- 20-27 indicates severe depression
Management
Management options for depression include:
- Active monitoring and self-help
- Address lifestyle factors (exercise, diet, stress and alcohol)
- Therapy (e.g., cognitive behavioural therapy, counselling or psychotherapy)
- Antidepressants (selective serotonin reuptake inhibitors are first-line)
A recent meta-analysis (BMJ 2024;384:e075847) found good evidence supporting that exercise is comparable to antidepressants or therapy as a treatment for depression. The more vigorous the exercise, the greater the effect size. Some forms of exercise were found to have a stronger effect than using SSRIs alone, and that exercise enhanced the effects of SSRIs.
NICE (2022) recommends not offering antidepressants first-line to patients with less severe depression (defined as less than 16 on the PHQ-9) unless they have a preference for taking antidepressants.
Patients with severe or psychotic depression require urgent specialist input and management.
The crisis resolution and home treatment team offer intensive support and treatment for patients having a mental health crisis without them being admitted to hospital (usually for a short period only).
Admission may be required where there is a high risk of self-harm, suicide or self-neglect or where there may be an immediate safeguarding issue.
Additional specialist treatments for unresponsive or severe depression include:
- Antipsychotic medications (e.g., olanzapine or quetiapine)
- Lithium
- Electroconvulsive therapy
Electroconvulsive Therapy
Electroconvulsive therapy (ECT) is a very safe and effective treatment for severe, medication-resistant and psychotic depression. It involves a course of treatments, for example, twice weekly for four weeks.
Under general anaesthesia, electrodes are placed on the patient’s head, and a brief electrical current is administered, which triggers a short generalised seizure lasting around 30 seconds.
Side effects include headache, muscle aches and short-term memory loss.
Psychotic Depression
Psychotic depression involves the symptoms of psychosis. Psychosis involves:
- Delusions (beliefs that are strongly held and clearly untrue)
- Hallucinations (hearing or seeing things that are not real)
- Thought disorder (disorganised thoughts causing abnormal communication and behaviour)
When psychosis accompanies depression, it generally indicates severe depression, although psychosis can occur with mild or moderate depression. Treatment involves a combination of antipsychotic drugs (e.g., olanzapine or quetiapine) and antidepressants. Electroconvulsive therapy (ECT) is also an option.
Postnatal Depression
There is a spectrum of postnatal mental health issues:
- Baby blues is seen in the majority of women in the first week or so after birth
- Postnatal depression is seen in about one in ten women, with a peak around three months after birth
- Puerperal psychosis is seen in about one in a thousand women, starting a few weeks after birth
Baby blues affect more than 50% of women in the first week or so after birth, particularly first-time mothers. It presents with symptoms such as mood swings, low mood, anxiety, irritability and tearfulness. Baby blues may be the result of a combination of significant hormonal changes, recovery from birth, sleep deprivation, increased responsibility and difficulty with feeding. Symptoms are usually mild, last only a few days and resolve within two weeks of delivery. No treatment is required.
Postnatal depression is similar to depression that occurs outside of pregnancy, with the classic triad of low mood, anhedonia (lack of pleasure in activities) and low energy. Typically, women are affected around three months after birth. Symptoms should last at least two weeks before postnatal depression is diagnosed. Treatment is similar to depression at other times, depending on the severity.
Puerperal psychosis is a rare but severe illness that typically has an onset between two to three weeks after delivery. Women experience the symptoms of psychosis, such as delusions, hallucinations, depression, mania, confusion and thought disorder. Women with puerperal psychosis need urgent assessment and input from specialist mental health services. They may require admission to the mother and baby unit, medications and potentially electroconvulsive therapy (ECT).
The Edinburgh postnatal depression scale can be used to assess how the mother has felt over the past week as a screening tool for postnatal depression. There are ten questions, with a score out of 30 points. A score of 10 or more suggests postnatal depression.
The mother and baby unit is a specialist unit for pregnant women and women who have given birth in the past 12 months. They are designed so the mother and baby can remain together and continue bonding. Mothers are supported to continue caring for their babies while they get specialist treatment.
Last updated June 2024
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