NURSING 2LA2 Lecture 7: Pathophysiology for Nursing Depression
18 Feb 2019
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Pathophysiology-Depression
1
Pathophysiology for Nursing Depression
Statistics
~10% of Canadians affected by mood disorders
• Suicide in ~15% of individuals with major depressive disorder
• Twice as prevalent in women than men → since women more apt to recognize mental
health issues and go to their doctor. Neurobiological basis for increased prevalence in
women is unknown but also thought to be related to differences in hormonal status or
stress response systems or to sexual differences between sexes in any of several brain
areas
o Men less likely to seek help
o Depression often masked by somatic complaints in men→ NIMH found when
speaking to men in focus groups that depression often becomes masked in men
like somatic complaints like migraines, back pain, IBS and therefore not
recognized as depression
• Mood disorders are disorders of emotion including mania and depression. These
disorders are highly under diagnosed and undertreated.
• Depression is among the leading causes of disability worldwide with approximately 8%
of adults experiencing major depressive episodes at some time in their lives.
• Prevalence of bipolar manic depression is 1% in pop at large and equally distributed
between men and women
DSM 5 Criteria for Depression
• Major depressive disorder
o Five (or more) symptoms must be present during the same 2-week period and
represent a change from previous functioning; at least one of the symptoms is
either (1) depressed mood or (2) loss of interest or pleasure(anhedonia).
▪ Others include changes in weight, appetite
▪ Insomnia or hypersomnia
▪ Psychomotor agitation or retardation
▪ Fatigue or loss of energy
▪ Feelings of worthlessness or excessive guilt
▪ Diminished ability to think or concentrate or indecisiveness
▪ Thoughts of death or suicidal ideation
• Mood disorders of emotion include mania and depression and depressive disorders
commonly divided into 2 categories:
o Major depressive disorder (depressed mood or loss of interest or pleasure in
nearly all activities)
o Persistent depressive disorder(dysthymia) depressed mood for most of day more
days than not for at least 2 years
• Sub classifications of depression (specifiers)
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Pathophysiology-Depression
2
o Medical illnesses like heart disease, diabetes, autoimmune disorders and pain are
comorbid diagnoses
o Other depressive disorders include
▪ Disruptive mood dysregulation disorder
▪ Premenstrual dysphoric disorder
▪ Substance medication induced depressive disorder
▪ Specified and unspecified depressive disorder
o Specifiers added to dx of depression or dysthymia are
▪ Anxious distress
▪ Mixed features
▪ Melancholic features
▪ Atypical features
▪ Psychotic features
▪ Catatonia
▪ Peripartum onset
▪ Seasonal pattern (DSM5)
Risk Factors for Depression
1. Childhood emotional, physical, and sexual abuses
2. Prior episode of depression
3. Family history of depressive disorder
4. Lack of social support
5. Stressful life event
6. Current substance abuse
7. Economic difficulties
Etiology of Depression
• Multi-factorial
• Dynamic interplay amongst
o Genetic predisposition
o Environment
o Life history
o Development
o Biological challenges
• Over past 40 years focused on deficits in neurotransmitter systems and currently
believed that MDD arise from complex interaction of genes and environmental factors.
Brain Math
• 1000 trillion = total numbers of synapses Larger than the # of stars in the galaxy
• Pathophysiology is what happens at cellular level to cause disease and for mental illness
it’s what happens inside brain that portion of cns that is contained in cranium
• 100 billion neurons or never cells and
• 10-50 trillion neuroglia which support nerve cells in brain
• brain has mass of 1300 grams or 3 lbs in adults
• on average each neuron forms 1000 synapses with other neurons
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find more resources at oneclass.com
Pathophysiology-Depression
3
• therefore, brain very complex organ and complex to understand how it works and what
happens at cellular level to cause neuron to have depression
• MDD more common in first degree relatives than gen pop
• Family twin and adoption studies suggest hereditary component to etiology mood
disorders
• Hereditability for depression estimated from twin studies as 31-42% with substantial
contribution of environmental effects unique to individuals of 58-67 so again the cause
is partly genetics and partly environment
• Scientists found gene or series of genes that cause depression and certain variations in
genes (polymorphisms) inc risk for depression
• Genes predispose individuals to MDD in many ways → genes help control metabolism of
neurotransmitters and receptors and # of particular types of neurons and their synaptic
connections, intracellular transduction of neuronal signals and speed with which all of
these can change in response to environmental stressors
• Serotonin transporter gene most studied in MDD since polymorphism that gives rise to
2 different alleles long and short
• People have 2 copies of each gene in their DNA hence a person can be homozygous for
long allele, homozygous for short allele or heterozygous one long and one short
o short allele slows down synthesis of serotonin transporter
o this reduces speed with which serotonin neurons can adapt to changes in
stimulation
o short allele in serotonin transporter gene slows down synthesis of serotonin
transporter leading to dysregulation of serotonin and this process implicated in
depression
Genetic Predisposition: Brain Derived Nerotropic Factor (BDNF)
• Important role in birth, survival and maturation of brain cells during development
• BDNF is a growth factor protein found in high concentration n brain important for
neuronal cell growth and synaptic changes that occur throughout person’s life
• Contributes to these processes by Activates DNA binding factors that stimulate gene
transcription of genes involved in serotonin function like the serotonin transporter and
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
~10% of canadians affected by mood disorders: suicide in ~15% of individuals with major depressive disorder, twice as prevalent in women than men since women more apt to recognize mental health issues and go to their doctor. Risk factors for depression: childhood emotional, physical, and sexual abuses, prior episode of depression, family history of depressive disorder, lack of social support, stressful life event, current substance abuse, economic difficulties. Important role in birth, survival and maturation of brain cells during development: bdnf is a growth factor protein found in high concentration n brain important for neuronal cell growth and synaptic changes that occur throughout person"s life. Contributes to these processes by activates dna binding factors that stimulate gene transcription of genes involved in serotonin function like the serotonin transporter and. Bdnf: val/met genotype: val and met alleles in gene that codes for bdnf polymorphism in gene that codes for.
