Chapter 14 Part 2. Mood Disorders and Treatments

Major Depressive Disorder

Characterized by an absence of happiness rather than increased sadness

Major Depressive Disorder 3 Facts

• Most common in women during the reproductive area

• Most commonly comes in periodic episodes

Depression and genetics

Moderate degree of heritability

No one gene has been identified as clearly linked to depression

People with early-onset depression (before age 30) more likely to have relatives with depression and anxiety disorders 

Late onset depression (after age 45) linked to relatives with circulatory problems

What are the four categories of anti-depressant drugs? 

Tricyclics

Selective serotonin reuptake inhibitors (SSRIs)

Serotonin norepinephrine reuptake inhibitors (SNRIs)

Monoamine oxidase inhibitors (MAOIs)

Tricyclics

Block transporter proteins that reabsorb serotonin, dopamine, and norepinephrine into the presynaptic neuron after release

Downside to tricyclics 

Because they also block histamine receptors, acetylcholine receptors, and certain sodium channels, they cause side effects of drowsiness, dry mouth, difficulty urinating, and (most dangerously) heart irregularities

Selective serotonin reuptake inhibitors (SSRIs)

Block the reuptake of the neurotransmitter serotonin

Prescribed more than tricyclics because it has fewer side effects, partly because it doesn’t block histamines and sodium channels.

Serotonin norepinephrine reuptake inhibitors (SNRIs)

Block the reuptake of serotonin and norepinephrine 

Unlike other antidepressants, the SNRIs improve certain aspects of memory

Monoamine oxidase inhibitors (MAOIs)

These drugs DO NOT block transmitters, they block the enzyme Monoamine oxidase, which metabolizes serotonin and catecholamines, so they remain in the synapse

Three natural alternatives to anti-depressants 

Cognitive-behavioural therapy 

Exercise 

Diet 

Electroconvulsive Therapy (ECT)

Electrically induced seizure used for the treatment of severe depression

While the reasons why ECT relieves depression is unknown, what are some theories?

Because it increases Brain-Derived Neurotrophic Factor (BDNF), which helps neurogenesis, being a neurotrophic factor

Unipolar disorder 

Characterized by alternating states of normality and depression

Bipolar disorder (formally manic depressive disorder)

Characterized by alternating states of  depression and mania

Bipolar disorder I vs bipolar disorder II 

Bipolar disorder I is characterized by full blown episodes of mania, whereas bipolar disorder II is characterized by much milder manic phases, called hypomania

Why are anti-depressants not good for bipolar disorder?

Because you don’t want the patient to have the anti-depressant during the manic (happy) phase.

First treatment for bipolar disorder

Lithium

The problem lithium is that the toxic dose is very close to the effective dose, so you could “treat and kill” the patient at the same time.

Second treatment for bipolar disorder

Valproate (Depakote) and Carbamazepine

Increases GABA activity, decreases glutamine activity, and also blocks the synthesis of arachidonic acid