Bipolar and Depressive Disorders — Comprehensive Notes (Markdown)
Mood disorders: classification (DSM-5-TR)
Mood disorders are classified as either bipolar and related disorders or depressive disorders.
Bipolar disorders include: bipolar I disorder, bipolar II disorder, cyclothymic disorder, substance/medication-induced bipolar and related disorder, and bipolar-related disorder due to another medical condition.
Depressive disorders include: disruptive mood dysregulation disorder (DMDD), major depressive disorder (MDD), persistent depressive disorder (PDD), premenstrual dysphoric disorder (PMDD), and substance/medication-induced depressive disorder.
In this introductory lecture, the focus is on major depressive disorder (MDD), persistent depressive disorder (PDD), with a brief outline of seasonal affective disorder (SAD).
Bipolar disorder involves fluctuations between very high and very low mood; the diagnosis requires consideration of manic, hypomanic, and depressive episodes.
Bipolar I and related features (as described in the transcript)
Bipolar I disorder is characterized by recurring mood episodes and, per the transcript, must include manic, depressive, and hypomanic episodes; however, the diagnostic criterion emphasized is the occurrence of at least one manic episode.
The fluctuation between high and low mood is a hallmark feature.
Manic episode (essential feature): a distinct period during which there is an abnormally elevated, expansive, or irritable mood and persistently increased energy, present most of the day nearly every day for at least 1\text{ week}.
Manic symptoms (examples listed):
inflated self-esteem or grandiosity
decreased need for sleep (e.g., feeling rested after only \approx 3\text{ hours} of sleep)
more talkative than usual or pressured speech
flight of ideas or subjective experience that thoughts are racing
distractibility
increased goal-directed activity (social, work, school, or sex) or psychomotor agitation
excessive involvement in activities with a high potential for painful consequences (e.g., unrestrained spending sprees, sexual indiscretions, foolish business investments)
Depressive episodes and hypomanic episodes may also occur in bipolar I, but the diagnostic criterion centers on the manic episode.
Major Depressive Disorder (MDD)
Trajectory: depressive symptoms may follow traumatic losses; symptoms must impact daily functioning.
DSM-5-TR criteria for MDD: during the same 2-week period, the person must have \ge 5 symptoms that represent a change from previous functioning, with at least one symptom being the presence of either depressed mood or anhedonia (loss of interest/pleasure).
Symptoms (the list includes but is not limited to):
depressed mood most of the day, nearly every day (subjective report or observed by others; in children/adolescents, mood may be irritable)
markedly diminished interest or pleasure in almost all activities
significant weight change or appetite disturbance
insomnia or hypersomnia
psychomotor agitation or retardation
fatigue or loss of energy
feelings of worthlessness or excessive or inappropriate guilt
diminished ability to think or concentrate, or indecisiveness
recurrent thoughts of death or suicidal ideation (with or without a plan or attempt)
A note on cognitive features: some individuals may experience delusional guilt or worthlessness.
Persistent Depressive Disorder (PDD)
Also known as dysthymic disorder.
Characterized by a chronic low mood that lasts more than 2\text{ years}.
Intervals of normal mood are infrequent and typically do not last longer than a few weeks or months.
Daily functioning is affected, but the impairment is often subtler than in MDD.
Seasonal Affective Disorder (SAD)
Characterized by depressive symptoms that occur in a seasonal pattern, most commonly in winter.
Associated with reduced sunlight exposure; colloquially called the “winter blues.”
SAD is defined by mood and behavior changes that track regular seasonal variation.
Causes and risk factors for bipolar and depressive disorders (summary of transcript)
Biological predisposition:
Bipolar disorder: strong familial loading; between 60\% and 90\% of people with bipolar disorder have a family history of mood disorders.
First-degree relatives of bipolar patients have about P=0.115 (11.5%) risk of developing bipolar disorder, which is about RR\approx 15\text{-}20 times higher than the general population.
Twin studies support genetic contributions with heritability estimates for bipolar disorder in the range h^2\in [0.40,0.70].
Depression shows heritability in the range h^2\in [0.30,0.40].
Neurobiology:
Reduced serotonin levels are linked with depressive symptoms due to serotonin’s role in energy, sleep, hunger, and mood regulation.
SSRIs (selective serotonin reuptake inhibitors) are commonly prescribed to treat depression by blocking reuptake of serotonin, increasing its availability in the synapse.
Environmental and developmental factors:
Early childhood and familial experiences contribute to depression risk; adults with depression are more likely to have been raised in disruptive, hostile, or negative environments.
Severe life stressors (e.g., loss of a loved one, job loss) often precede depression by about 6\text{ to }9\text{ months} in a large proportion of cases (approximately 90\% of people who become depressed).
Highly critical family environments increase relapse risk; relational dynamics (e.g., lack of intimate relationships) contribute to vulnerability, especially in women.
Life stressors in adulthood can prolong recovery and increase relapse risk.
Cognitive theories:
Learned helplessness: depressive attribution style involves internal, stable, and global explanations that increase vulnerability to depression (e.g., partner breakup leading to belief of being unlovable).
Beck’s negative cognitive triad: pessimistic interpretations of events about the self, the world, and the future; cognitive distortions convert neutral/positive events into negative experiences.
Psychodynamic theories:
Depression may be linked to early attachment patterns; fear of rejection or abandonment can predispose to depressive states.
Interpersonal focus: some depression is driven by relationship-related issues; autonomy/achievement-related depression arises from failures in those domains.
Cultural factors and global considerations:
Culture, gender, and language shape how mental illness is experienced, sought for help, and treated.
Depression rates differ across populations (e.g., relatively low in some Chinese populations in Asia; higher risk for Chinese immigrants to Australia if integration is perceived as poor).
Social determinants of health and First Nations health context:
Social determinants include birth, growth, living, work, and age conditions that drive health inequalities (e.g., access to healthcare, education, housing).
Structural disadvantages in policy, economics, and resource distribution underlie health disparities.
Aboriginal and Torres Strait Islander peoples show higher rates of mental health issues, with suicide deaths nearly twice as high, intentional self-harm hospitalizations about three times higher, and distress rates about 2.5 times higher than non-Indigenous Australians.
Historical and ongoing factors include social and historical trauma (colonialism) and economic disadvantage contributing to grief, loss, trauma, and broader health inequities.
Social determinants of health framework:
Health inequalities are largely attributed to unequal access to health care, education, work conditions, housing, and the social distribution of power and resources.
National health policy context (Australia):
The ten-year national Aboriginal and Torres Strait Islander health plan (2021–2031) aims to address health targets and priority reforms through a trauma-informed, healing-oriented approach.
Priorities include social and emotional well-being and suicide prevention, with a focus on culturally sensitive prevention and treatment strategies to mitigate inequalities.
Implications and connections across topics
Classification and diagnosis rely on DSM-5-TR criteria that balance biology, cognition, and environment.
The interplay of genetic predisposition and life stressors explains why some individuals develop mood disorders under certain circumstances while others do not.
Cognitive and psychodynamic theories offer frameworks for understanding internal experiences (e.g., negative attribution styles, attachment patterns) that influence mood disorder development and maintenance.
Cultural and social determinants emphasize that treatment must be culturally sensitive and accessible, particularly for Indigenous populations and immigrant communities.
Public health policies (e.g., health plans for Indigenous populations) illustrate how research translates into practice and prevention at the population level.
Key takeaways
Mood disorders are categorized into bipolar and depressive disorders, with subtypes and specifiers under each.
Bipolar I requires a manic episode; depressive and hypomanic episodes may occur but are not required beyond the manic criterion.
Major depressive disorder requires \ge 5 symptoms over a 2-week period, with at least one being depressed mood or anhedonia.
Persistent depressive disorder is a chronic, lower-grade depression lasting >2\text{ years}, with brief periods of normal mood.
Seasonal affective disorder involves depressive symptoms tied to seasonal changes, commonly winter.
Genetic and neurobiological factors contribute substantially to mood disorders, with heritability estimates in the ranges: bipolar h^2\in [0.40,0.70]; depression h^2\in [0.30,0.40]; and family history markedly increases risk.
Serotonin dysregulation and SSRIs play a key role in pharmacological treatment for depressive symptoms according to the transcript.
Life stressors, attachment, cognition, culture, and social determinants all shape the onset, course, and treatment outcomes of mood disorders.
Culturally sensitive prevention and treatment frameworks are essential to address health inequalities, particularly for First Nations peoples and immigrant populations.