Biological treatments for mood disorders

• Exogenous- Depression follows clear preceding events, something (environmental) has happened to the individual to cause depression
• Endogenous- Depression occurs in the absence of preceding events, appears to be caused by internal (biological) factors
• Seems to be no obvious cause for a person's depression
• Endogenous depression is assumed and a biological treatment is likely to be chosen by a clinician

Monoamine oxidase inhibitors (MAOIs)

• Monoamine oxidase in an enzyme that interacts with and breaks down the monoamines serotonin (5-HT) and noradrenaline (na) once a message has been relayed across the synapse
• Function- Believed that depressed patients have low levels of 5-HT and na, monoamine oxidase inhibitors prevent the destruction of these neurotransmitters allowing for levels to accumulate in the synapse and remain for longer- neurotransmission returns to normal and symptoms are reduced
• Effectiveness- 50% of mild to severely depressed patients who take MAOIs recover from depression. Good for depression where anxiety is a symptom
• Side effects-
  >Insomnia, dry mouth and dizziness
  >Interact with certain foods causing dangerously high blood pressure and sudden death

Tricyclic Antidepressants (TCAs)

• Thought that the reuptake mechanism may be too successful in some people causing low serotonin (5-HT) and noradrenaline (na) levels in the synapse
• Function- Block the reuptake of 5-HT and na, leaving the neurotransmitter in the synapse for longer. This results in increased activity and a reduction in symptoms
• Effectiveness- TCAs are commonly prescribed. 60-65% effective and do not require dietary restrictions
• Side effects-
  >Dry mouth, confusion, impaired memory, sedation, analgesia (pain relief)
  >Fatal in overdose, GPs must take care when prescribing this drug to suicidal/severly depressed patients

Selective serotonin reuptake inhibitors (SSRIs)

• The most recently discoevered antidepressants, include Sertraline (Lustral) and Fluoxetine (Prozac)
• Function- Only block the reuptake of serotonin (5-HT) and don't affect other neurotransmitters or biochemical processes --> patients experience fewer side effects
• Effectiveness- Equally as effective as Tricyclic antidepressants (65%) but are often preferred as they don't have the same side effects (not fatal in overdose). More suitable for severly depressed/suicidal patients
• Side effects-
  >Headaches, nervousness, insomnia, sweating
  >Sexual dysfuntion reported in 40-60% of patients taking SSRIs (thought to be a significant contributor to non-compliance)

MAOIs

• More than half of patients improve when taking these drugs, BUT around half don't suggesting not all depression is biological in cause (e.g. exogenous depression)
• Improvement is not experperienced until 4-6 weeks after the start of the course despite neurotransmitter levels returning to normal in only a few days- questions whether low serotonin (5-HT) and noradrenaline (na) levels are the cause of depression, issues with patient compliance due to there being no immediate effect
• Patient must continue to take the drug for at least 6 week to reduce risk of relapse- patients may stop taking the drug prematurely once recovered

Side effects

• These may make the patient reluctant to take the drug due to the resulting unpleasant symptoms
• E.g. MAOIs require patients to go on a strict diet

Treats the symptoms not the cause

• Criticised as a 'quick fix' due to the medication not actually treating the cause
• Assumes depresion is endogenous and so ignores other potential factors

Relapse

• Due to the cause not being addressed, relapse is a problem
• Research shows that once a person has recovered from one episode of depression, they have an increased vulnerability to further episodes
• Suggested that treatment should take a multi-modal approach- therapy and medication 

Lithium

• Has mood stabilising effects- treats both the manic and depressive phases of the disorder
• Not fully understood how it works- closely related to sodium so thought it may increase the presynaptic uptake of noradrenaline (na) OR it may inhibit the release of na
• Effectiveness- 80% efficacy in treating manic and depressive symptoms, issues with compliance have meant that studies have found that less than 40% of patients remain well= HIGH efficacy, LOW effectiveness
• Side effects-
  >Vomiting, sluggishness, cognitive slowing, kidney damage, weight gain (30% obesity)
  >Toxic problems
  >Achieving the correct dosage for any individual is a delicate process

Non-compliance

• The course of the illness after stopping lithium treatment is worse- Lithium is a lifelong treatment
• Psychological support and family therapy can help the patient stay on the drug

Efficacy

• How successful a drug is in relieving the symptoms of a disorder

Effectiveness

• The success of the drug as a treatment
• Highly dependant on the severity of side effects and a patient's willingness to comply with dosage requirements

• Smith and Glass- reviewed 400 studies of a wide variety of treatments and found that all were more effective than no treatment at all. They also found that patients that discontinue antidepressant medication have a 50% chance of relapse in the first 6 months after therapy unless it is folled by psychotherapy--> suggests and eclectic approach is most effective
• Relapse rates (12 weeks of...)- Drug therapy, no continuation--> 50%, Drug therapy, continued for 1 yr--> 32%, Cognitive therapy, no continuation--> 21%, Drug and cognitive, no continuation--> 15%
• Importance of drug therapy- elevate a seriously depressed patient's mood to enable them to function cognitive, behavioural or psychodynamic therapy sessions
• ECT- helpful for 50-80% of severely depressed, drug resistant individuals