02-06-2026 (1)
Depression is
1. Pervasive
a. Lots of people suffering from it
2. Diverse
a. Symptoms differ
3. Debilitating
a. Seriously affects someone or something's strength or ability to carry
on with regular activities
Quotes
“Depression is […] so mysteriously painful and elusive in the way
it becomes known to the self—to the mediating intellect—as to
verge close to being beyond description. “
“It thus remains nearly incomprehensible to those who have
not experienced it in its extreme mode.”
– William Styron
“If I had to define depression,
I would say it is a biochemical disorder,
with a genetic component,
influenced by early experiences,
where somebody can’t appreciate sunsets.”
– John Sapolsky
Defining depression
A continuum
- “Normal” state
→ feeling sad/”depressed”/gloomy
→ depression
→ depressive disorder (diagnosable)
Diagnosis
Core symptoms (have to be there for 2 weeks)
1. Anhedonia: No interest or pleasure in all or almost all activities
2. Depressed mood: most of the day, nearly every day
,Other symptoms (have to be 4+)
- Weight loss or gain, or decrease or increase in appetite.
- Sleep problems
- Agitation (on edge) or retardation (slow), observable by others
- Fatigue or loss of energy
- Feelings of worthlessness, guilt
- Loss of focus, indecisiveness
- Thoughts about death
+ Significant suffering/impairment in social or professional functioning
Symptoms of depression
Relevant mood disorders
Major depressive disorder
At least 2 weeks, at least 5 symptoms
Persistent depressive disorder (dysthymia)
At least 2 years, 2-4 symptoms
Minor depression (older DSM versions)
At least 2 weeks, 2-4 symptoms
Bipolar disorder
Additional manic episodes
Switching between highs and lows (BIpolar ipv UNIpolar)
,Depressive disorder subtypes
Differential diagnosis
Important to differentiate other things from depression
Unipolar or bipolar depression?
→ bipolar has manic episodes
Psychotic depression or schizophrenia?
→ depression has the symptom anhedonia also, schizo not
Depression or substance abuse?
→ depressive type symptoms can occur with substance abuse → just have to ask
Depression or grief?
→ difficult to differentiate
Depression, suicidality, suicide
- Depression is the most important predictor of suicide… but most people
with depression are not suicidal!
- Suicidality is associated with most mental disorders
- Suicidality can best be seen as a separate problem that often co-occurs
with depression
- Suicidality is an important urgent indicator for treatment
Epidemiology
In any given year 4.4 - 5% of the world population has MDD
→ increase of 41% from 1990 to 2023
Lifetime prevalence → ~10%
, Depressive episodes
- Average duration of episode is 6 months (but: wide variation)
- Most acute episodes remit within a year, but 12-34% have chronic
depression
- High recurrence rates: 27-45% over 20 years in community samples, much
higher in clinical samples
- Recurrence risk increases with every additional episode
Correlates and comorbidity
- Prevalence about twice as high in women as in men
- High comorbidity: especially anxiety disorders, substance use disorders,
personality disorders
- Help-seeking is low (7-28%), even in countries with broadly available and
free healthcare
Children and adolescents
Toddlers: 1 %
Primary school age: 1-2 %
Adolescents: ~5%
Young adults: 7.2%
Median age of onset: 26 (17-37) in high-income countries and 24 (17-35) in low-
and middle income countries
Depression is
1. Pervasive
a. Lots of people suffering from it
2. Diverse
a. Symptoms differ
3. Debilitating
a. Seriously affects someone or something's strength or ability to carry
on with regular activities
Quotes
“Depression is […] so mysteriously painful and elusive in the way
it becomes known to the self—to the mediating intellect—as to
verge close to being beyond description. “
“It thus remains nearly incomprehensible to those who have
not experienced it in its extreme mode.”
– William Styron
“If I had to define depression,
I would say it is a biochemical disorder,
with a genetic component,
influenced by early experiences,
where somebody can’t appreciate sunsets.”
– John Sapolsky
Defining depression
A continuum
- “Normal” state
→ feeling sad/”depressed”/gloomy
→ depression
→ depressive disorder (diagnosable)
Diagnosis
Core symptoms (have to be there for 2 weeks)
1. Anhedonia: No interest or pleasure in all or almost all activities
2. Depressed mood: most of the day, nearly every day
,Other symptoms (have to be 4+)
- Weight loss or gain, or decrease or increase in appetite.
- Sleep problems
- Agitation (on edge) or retardation (slow), observable by others
- Fatigue or loss of energy
- Feelings of worthlessness, guilt
- Loss of focus, indecisiveness
- Thoughts about death
+ Significant suffering/impairment in social or professional functioning
Symptoms of depression
Relevant mood disorders
Major depressive disorder
At least 2 weeks, at least 5 symptoms
Persistent depressive disorder (dysthymia)
At least 2 years, 2-4 symptoms
Minor depression (older DSM versions)
At least 2 weeks, 2-4 symptoms
Bipolar disorder
Additional manic episodes
Switching between highs and lows (BIpolar ipv UNIpolar)
,Depressive disorder subtypes
Differential diagnosis
Important to differentiate other things from depression
Unipolar or bipolar depression?
→ bipolar has manic episodes
Psychotic depression or schizophrenia?
→ depression has the symptom anhedonia also, schizo not
Depression or substance abuse?
→ depressive type symptoms can occur with substance abuse → just have to ask
Depression or grief?
→ difficult to differentiate
Depression, suicidality, suicide
- Depression is the most important predictor of suicide… but most people
with depression are not suicidal!
- Suicidality is associated with most mental disorders
- Suicidality can best be seen as a separate problem that often co-occurs
with depression
- Suicidality is an important urgent indicator for treatment
Epidemiology
In any given year 4.4 - 5% of the world population has MDD
→ increase of 41% from 1990 to 2023
Lifetime prevalence → ~10%
, Depressive episodes
- Average duration of episode is 6 months (but: wide variation)
- Most acute episodes remit within a year, but 12-34% have chronic
depression
- High recurrence rates: 27-45% over 20 years in community samples, much
higher in clinical samples
- Recurrence risk increases with every additional episode
Correlates and comorbidity
- Prevalence about twice as high in women as in men
- High comorbidity: especially anxiety disorders, substance use disorders,
personality disorders
- Help-seeking is low (7-28%), even in countries with broadly available and
free healthcare
Children and adolescents
Toddlers: 1 %
Primary school age: 1-2 %
Adolescents: ~5%
Young adults: 7.2%
Median age of onset: 26 (17-37) in high-income countries and 24 (17-35) in low-
and middle income countries
