What is clinical depression?

Clinical depression is also known as major depressive disorder (MDD) and is a serious mental health condition characterized by persistent feelings of sadness, hopelessness, and a lack of interest or pleasure in daily activities.

Unlike occasional sadness or mood swings, clinical depression notably impacts a person’s thoughts, emotions, and physical well-being for weeks, months, or even years.

Depression affects brain chemistry, often involving imbalances in neurotransmitters such as serotonin, dopamine, and norepinephrine, which regulate mood.

It can be triggered by genetic factors, life stressors, trauma, medical conditions, or a combination of the above.

Types of clinical depression

There are several different types of clinical depression, each with unique characteristics. Below are the main types:

1. Major depressive disorder (MDD)
   • The most common form of depression.
   • Symptoms last for at least two weeks and interfere with daily life.
   • This includes low energy, appetite changes, sleep disturbances, and suicidal thoughts in severe cases.
2. Persistent depressive disorder (PDD) (dysthymia)
   • A chronic, long-term form of depression lasting two years or more.
   • Symptoms are milder than MDD, but still cause emotional distress and minimal motivation.
   • Often described as feeling “down” or “not quite right” most of the time.
3. Bipolar disorder (manic depression)

   

   • Involves extreme mood swings between depressive episodes and manic episodes (periods of high energy, impulsiveness, and euphoria).
   • Depressive episodes mirror MDD, while mania involves risk-taking behaviors, insomnia, and racing thoughts.
4. Seasonal affective disorder (SAD)
   • A type of depression that occurs during specific seasons, typically fall and winter, when sunlight is limited.
   • Indications improve in spring or summer.
   • Typically linked to changes in melatonin and serotonin concentrations due to reduced sunlight exposure.
5. Psychotic depression
   • A serious form of depression that includes psychotic symptoms, such as hallucinations (seeing or hearing things that aren’t there) or delusions (false beliefs).
   • Often requires hospitalization and intensive treatment.
6. Postpartum depression (PPD) (perinatal depression)
   • It can affect women after childbirth due to hormonal changes, stress, and lifestyle adjustments.
   • More severe than the “baby blues” and can last for months if untreated.
   • Symptoms include anxiety, sadness, mood swings, and difficulty bonding with the baby.
7. Premenstrual dysphoric disorder (PMDD)
   • A severe form of premenstrual syndrome (PMS) that causes extreme mood swings, irritability, and depression before menstruation.
   • Symptoms subside after menstruation begins.
8. Atypical depression
   • A subtype of MDD with unique symptoms, such as mood reactivity (temporary mood improvement in response to positive events).
   • Symptoms include excessive sleeping, increased appetite, and heavy limbs (feeling weighed down).

There are a few other forms that are less common but still recognized by mental health professionals:

1. Situational depression (adjustment disorder with depressed mood)

• • Usually occurs after a major life event or stressor, such as the loss of a loved one, job loss, divorce, or trauma.
  • Signs are similar to major depression but are directly tied to a specific event and typically resolve once the person adapts.
  • It is considered a subtype of adjustment disorder, though not classified as a standalone disorder in the DSM-5.

2. Double depression

• • Occurs when someone with persistent depressive disorder (PDD) (dysthymia) experiences an episode of major depressive disorder (MDD).
  • The individual has a baseline of chronic low mood but falls into deeper depressive episodes periodically.
  • This can make recovery more challenging because the person is already accustomed to long-term depression.

3. Substance-induced depression

• • Caused by alcohol, drugs, or medication withdrawal.
  • Certain substances, such as alcohol, opioids, benzodiazepines, and stimulants, can cause depressive symptoms during use or withdrawal.
  • Some prescription medications, such as corticosteroids, hormonal treatments, and isotretinoin (used for acne), have been linked to depression.

4. Depressive disorder due to a medical condition
   

• • Depression can result from underlying medical conditions such as:
    • Thyroid disorders (hypothyroidism).
    • Chronic pain conditions (fibromyalgia, arthritis).
    • Neurological disorders (Parkinson’s disease, multiple sclerosis).
    • Cancer, heart disease, or diabetes.
  • The condition itself or the stress of dealing with a chronic illness can add to depression.

5. Masked depression

• • A controversial and less commonly recognized form where depression is presented through physical symptoms rather than emotional distress.
  • Individuals may not feel sad but instead experience:
    • Unexplained headaches, fatigue, or digestive issues.
    • Irritability or chronic pain.
  • This type is often misdiagnosed because the emotional aspect is “masked” by physical symptoms.

6. Existential depression

• • This form is linked to deep philosophical or existential crises and is more common among highly intellectual or introspective individuals.
  • May involve questions about life’s purpose, mortality, meaning, or feeling disconnected from society.
  • It can be triggered by sizable life events, such as aging, loss, or exposure to suffering.

7. Treatment-resistant depression (TRD)

• • A severe and persistent form of depression that does not respond to standard treatments like antidepressants or therapy.
  • Individuals may require alternative treatments, such as:
    • Electroconvulsive therapy (ECT).
    • Ketamine therapy.
    • Transcranial magnetic stimulation (TMS).

8. Neurotic depression (anxious depression)
   

• • A form of depression with high anxiety, excessive worry, and little stress tolerance.
  • People often experience self-doubt, guilt, and hypersensitivity to criticism.
  • Overlaps with generalized anxiety disorder (GAD) and regularly involves rumination (overthinking negative thoughts).

9. Postoperative depression

• • It may arise after major surgery due to anesthesia effects, prolonged recovery, physical pain, or changes in body image (such as after amputation or cosmetic surgery).
  • It can also be triggered by loss of mobility, independence, or medical complications.

10. Endogenous depression

• • Thought to be biologically based rather than triggered by external events.
  • More closely connected to genetic factors, neurotransmitter imbalances, and brain chemistry.
  • Symptoms are severe and continual, even in the absence of identifiable life stressors.

11. Reactive (situational) depression

• • The opposite of endogenous depression since it’s triggered by a traumatic or stressful life event, like the death of a loved one, divorce, or financial loss.
  • It can sometimes overlap with situational depression (adjustment disorder with depressed mood) but may persist longer and develop into major depressive disorder (MDD).

12. Agitated depression
    

• • A lesser-known type where, instead of sluggishness and fatigue, people experience restlessness, irritability, and agitation.
  • Warning signs include pacing, fidgeting, frustration, and a short temper.
  • Common in older adults and sometimes overlaps with bipolar disorder.

13. Vascular depression

• • Seen in older adults and linked to poor blood flow to the brain (vascular issues).
  • Often coexists with conditions like hypertension, stroke, or diabetes.
  • Symptoms comprise cognitive decline, memory problems, and slowed thinking, making it harder to distinguish from dementia.

14. Catatonic depression

• • A rare and stark subtype of major depression where people experience motor disturbances, such as:
    • Immobility or extreme restlessness.
    • Repeating meaningless movements or speech.
    • Mutism (not speaking at all).
  • Often requires hospitalization and intensive psychiatric care.

Conclusion

Clinical depression is not a one-size-fits-all condition since it varies in severity, duration, and symptoms.

Depression comes in many forms, and some of these subtypes may overlap or coexist in the same individual.

Because symptoms vary widely, an accurate diagnosis from a mental health professional is essential for proper treatment.

It’s advised to seek professional help, as treatment options like therapy, medication, and lifestyle changes can make an enormous difference.