Depression – B. Pharma 2nd Semester Pathophysiology notes pdf


Depression Definition, Etiology, and Pathophysiology


At the end of this lecture, students will be able to

  • Explain the definition of depression
  • Explain the  etiology of depression
  • Explain the pathophysiology of depression


Depression is a state of low mood and aversion that can affect a persons’ thoughts, behavior, feelings, and sense of well being.

Depression, a multifaceted mental health ailment affecting a substantial global populace, transcends mere sadness and wields profound repercussions on daily life, relationships, and overall well-being. To bestow effective aid and treatment upon the afflicted, comprehension of depression’s essence, its genesis, and underlying physiological processes is pivotal. This article delves into the intricate labyrinth of depression, elucidating its definition, causative factors, and the intricate biological tapestry behind it.

Depression, also known as major depressive disorder (MDD), represents a clinical condition characterized by enduring sentiments of melancholy, despondency, and a waning interest in once-enjoyed pursuits. Unlike ephemeral emotions, it manifests as a persistent state, enduring for weeks, months, or even years. Various subtypes of depression exist, including seasonal affective disorder (SAD), postpartum depression, and persistent depressive disorder (PDD).

Causes of Depression

  • Family History
  • Having a family members who have depression may increase a person’s risk
  • Imbalances of certain chemicals in the brain may lead to depression
  • Major Life Changes
  • Positive or negative events can trigger depression. Examples include the death of a loved one or a promotion
  • Major Illnesses such as heart attack, stroke or cancer may trigger depression
  • Certain medications used alone or in combination can cause side effects much like the symptoms of depression
  • Use of Alcohol or other Drugs can lead to or worsen depression
  • Depression can also occur for no apparent reason!

Types of depression

Major depression

  • Inability to enjoy life and experience pleasure
  • Symptoms are constant, ranging from moderate to severe
  • Some people experience just a single depressive episode in their lifetime, but more commonly, major depression is a recurring disorder

Atypical Depression

  • Specific symptom pattern, including a temporary mood lift in response to positive events
  • Other symptoms include weight gain, increased appetite, sleeping excessively, a heavy feeling in the arms and legs
  • Atypical depression responds better to some therapies and medications than others

Bipolar disorder

People with this type of illness change back and forth between periods of depression and periods of mania (an extreme high)

Symptoms of mania may include:

  • Less need for sleep
  • Overconfidence
  • Racing thoughts
  • Reckless behavior
  • Increased energy
  • Mood changes are usually gradual but can be sudden

Season affective disorder

This is a depression that results from changes in the season. Most cases begin in the fall or winter, or when there is a decrease in sunlight

Depression Pathophysiology

  • Biogenic amine hypothesis: Decreased brain levels of the neurotransmitters norepinephrine (NE), serotonin (5-HT), and dopamine (DA)
  • Postsynaptic changes in receptor sensitivity: Changes in sensitivity of NE or 5-HT2 receptors may relate to its onset
  • Dysregulation hypothesis: A failure of homeostatic regulation of neurotransmitter systems, rather than absolute increases or decreases in their activities

Depression Symptoms

  • Vary from person to person
  • 2 key signs – loss of interest in things you like to do and sadness or irritability

Additional signs of depression

  • Feeling empty
  • Inability to enjoy anything
  • Hopelessness
  • Loss of sexual desire
  • Loss of warm feelings for family or friends
  • Feelings of self-blame or guilt
  • Loss of self-esteem
  • Inexplicable crying spells, sadness or irritability

Changes in behavior and attitude

These may include:

  • General slowing down
  • Neglect of responsibilities and appearance
  • Poor memory
  • Inability to concentrate
  • Suicidal thoughts, feelings or behaviors
  • Difficulty making decisions

Physical complaints

  • Sleep disturbances such as early morning waking, sleeping too much or insomnia
  • Lack of energy
  • Loss of appetite
  • Weight loss or gain
  • Unexplained headaches or backaches
  • Stomachaches, indigestion or changes in bowel habits

Etiology and Risk Factors

The genesis of depression results from a confluence of elements. Biological factors, encompassing genetics and familial lineage, may render certain individuals more susceptible. Psychological aspects, such as personality traits and coping mechanisms, also contribute. Furthermore, environmental elements, such as traumatic occurrences or chronic stress, possess the potency to incite or exacerbate depression.

Manifestations of Depression

Depression presents with an array of symptoms, encompassing both emotional and physical dimensions. Emotionally, individuals may grapple with persistent sorrow, feelings of emptiness, and a profound sense of worthlessness. Physically, changes in appetite and weight, disturbances in sleep patterns, and inexplicable aches and pains may occur.

Diagnosis and Evaluation

Diagnosing depression hinges upon the criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Healthcare practitioners may resort to diverse screening and assessment tools to gauge the gravity and ramifications of depression in an individual’s life.

Impact on Daily Life

The tendrils of depression can markedly impede an individual’s capacity to function on a daily basis. Productivity at work or school may diminish, relationships with family and friends can fray, and a propensity to withdraw from social engagements may ensue.

Approaches to Treatment

Depression, a malady amenable to treatment, responds favorably to a variety of approaches. Psychotherapy, encompassing cognitive-behavioral therapy (CBT) and interpersonal therapy (IPT), empowers individuals to confront negative thought patterns and refine coping strategies. Antidepressant medications may be prescribed to rectify neurotransmitter imbalances. Additionally, lifestyle modifications, including regular exercise and a balanced diet, can complement other therapeutic modalities.

Supplementary Therapies

Beyond conventional treatments, complementary therapies display promise in supporting those grappling with depression. Regular exercise, for instance, holds potential to uplift mood and alleviate depressive symptoms. Practices like mindfulness and meditation nurture emotional resilience.

Preventive Measures

Detecting early signs of depression holds profound significance in effectuating timely intervention. Augmenting resilience via coping skills and stress management serves as a protective shield against depression.

Supporting Loved Ones with Depression Support from friends and family remains indispensable for individuals contending with depression. Familiarity with offering emotional support, adept listening, and encouragement towards seeking professional assistance can make a momentous difference.

Shattering the Stigma Eradicating the stigma enshrouding mental health forms a critical cornerstone in fostering open dialogues about depression. Educating and raising awareness combat discrimination and enhance access to mental health resources.

Depression Across Age Groups Depression spares no age demographic. The manifestation of depression in children and adolescents differs from that observed in adults. Similarly, depression in the elderly may be overlooked, potentially leading to inadequate treatment.


Depression, a labyrinthine mental health condition, necessitates our empathy and comprehension. By grasping its essence, etiology, and pathophysiology, we can better serve and treat those ensnared by its grasp. For those grappling with depression or supporting someone in the throes of it, remember that seeking professional aid is paramount, and a brighter tomorrow awaits.


Is depression synonymous with weakness?

No, depression transcends notions of weakness. It represents a medical condition befalling anyone, irrespective of their fortitude or resilience.

Can depression be wholly eradicated?

While an absolute “cure” for depression remains elusive, efficacious management and treatment can be achieved through appropriate therapies and support.

Do antidepressants trigger addiction?

Antidepressants are not inherently addictive, though discontinuation may entail withdrawal effects. Collaborating closely with healthcare providers during medication adjustments remains essential.

Can lifestyle changes single-handedly address depression?

In mild cases, lifestyle adjustments such as regular exercise and wholesome nutrition may suffice. However, moderate to severe instances necessitate supplementary therapeutic interventions.

Is it natural to experience occasional sadness?

Indeed, occasional pangs of sadness constitute a normal facet of the human experience. However, persistent and life-disruptive sadness may indicate depression warranting attention.


  • Depression is a state of low mood and aversion  that can affect a person’s thoughts, behavior, feelings, and sense of well being
  • Etiology: family history, major life changes, drugs, work
  • Decreased brain levels of the neurotransmitters norepinephrine (NE), serotonin (5-HT), and dopamine (DA), changes in sensitivity of NE or 5-HT2 receptors –  failure of homeostatic regulation of neurotransmitter systems, rather than absolute increases or decreases in their activities

Depression Pathophysiology Notes Download

Depression Pathophysiology PDF Notes

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