Depression - Physiology & Pharmacology Flashcards
What is depression?
The most common mental health issue - ICD10 mood [affective] disorders (F30-39)
What are the 2 patterns of depressive states?
- Unipolar: low level of mood affecting QoL treated with CBT/ADs - includes dysthymia (low level, chronic) + MDD (clinical depression including atypical)
- Bipolar: recurrent episodes/cycles of mania + depression treated with antipsychotics - includes bipolar disorder + cyclothymia (low level)
What are the 2 forms of bipolar disorder?
1 - classic type with cycles of mania and depression
2 - milder version presenting with hypomania (enhanced mood etc.) but no psychotic symptoms
What are the key symptoms of depression?
Persistent sadness or low mood
Marked loss of interests or pleasure
What symptoms should you look for if key symptoms of depression present?
Disturbed sleep Altered appetite/weight Fatigue/loss of energy Agitation or slowing of movements Poor concentration or indecisiveness Feeling worthless or excessive/inappropriate guilt Suicidal thoughts/acts
How would you diagnose major depressive disorder (MDD)?
Patient has either 1 or both key symptoms with an additional 2/3 of the others
What are the 3 grades of major depressive disorder (MDD)?
- Mild: few if any symptoms in excess of 4/5 required to make diagnosis and only minor functional impairment
- Moderate: symptoms or functional impairment between mild + severe
- Severe: most symptoms that markedly interfere with functioning w/ or w/o psychotic symptoms
What does the DSMV require for a depression diagnosis?
More than 5 symptoms occurring nearly everyday for 2 weeks for diagnosis of mild depression and for more than 2 years for chronic depression - more commonly used for Psychiatry over ICD-10 (requires more than 4 symptoms)
What circuitry is involved in depression?
- Reward vs stress circuits
- Decreased activity in prefrontal cortex and hippocampus
- Increased activity in amygdala and hypothalamus
What does imaging show in patients with depression?
Differences in regional activation reversed by AD use - myriad results
What theories for depression exist?
- Neurotransmitter: monoamine (5-HT and NA) decrease
- Neurohormonal: steroids + HPA axis (stress/anxiety)
- Immuno (auto?)
- Circadian
Where is serotonin (5-HT) produced? What does it do?
Produced mainly at raphe nuclei (also ENS) of brainstem acting centrally in multiple areas and involved in mood, agitation, OCD, anxiety, appetite, insomnia, sexual function, nausea/vomiting and GI function
Where is noradrenaline (NA) produced? What does it do?
Produced mainly at locus coeruleus (LC) and lateral tegmental area (LTC) acting centrally + peripherally (particularly involved in ANS transmission) having multiple functions such as depression, attention, energy homeostasis, agitation, emotions, BP, HR, bladder control + motor function
How do serotonin (5-HT) and noradrenaline (NA) interact?
Large interaction between 5HT and NA neurons centrally - interactions in brainstem speed activity whilst in cortex, activity is slowed
What is the role of inflammation in depression?
Inflammatory mediators lead to microglia activation, cell dysfunction and cell death which can lead to a spectrum of disorders - perhaps chronic low level inflammatory response in CNS in depression
What is the gut-brain axis?
Significant communication between ENS, ANS + CNS - gut microflora acts as barrier so nothing can get through to change brain function but inflammation in gut can trigger altered brain activity where altered microbiota can lead to breakdown of protection (‘leaky gut’) so substances can get into brain via circulation and leaky part of hypothalamus which is why probiotics reduce anxiety and improve mood
What is the role of neurogenesis in depression?
Depression associated with decreased dendritic arborisation also with decreased no. of synapses and overproduction of receptors - deficit can be reversed by neuronal growth factors (e.g. BDNF) + ADs
What are the non-pharmacological treatments for depression?
CBT TMS tDCS ECT DBS