​Biological Psychology – Symptoms and Diagnosis of Schizophrenia


What are the symptoms of schizophrenia?


Answer:
The symptoms of schizophrenia are divided into positive symptoms and negative symptoms. It is important to be able to identify and clearly distinguish between these two categories.

• Positive symptoms involve the presence of abnormal behaviours or experiences.

• Negative symptoms involve the absence or reduction of normal functioning.

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What are positive symptoms of schizophrenia?


Answer:
Positive symptoms are behaviours or experiences that are added to normal functioning and would not normally be present.


They include:

• Hallucinations

• Delusions

• Thought disorders

• Disorganised speech

• Disorganised or catatonic behaviour

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What are negative symptoms of schizophrenia?


Answer:
Negative symptoms involve the loss or reduction of normal behaviours and emotional functioning.


They include:

• Flattened emotional responses

• Poverty of speech (Alogia)

• Lack of initiative or persistence

• Inability to experience pleasure (Anhedonia)

• Lack of motivation (Avolition)

• Social withdrawal

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What are the diagnostic criteria for schizophrenia?


Answer:
To be diagnosed with schizophrenia, an individual must:

• Present with at least two characteristic symptoms.

• Experience social or occupational dysfunction.

• Show symptoms for at least one month before diagnosis.

• Have signs of the disorder present for at least six months.

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What are delusions?


Answer:
Delusions are false beliefs that remain firmly held despite evidence that they are untrue.


Common examples include:

• Persecutory delusions – believing others are trying to harm or persecute them.

• Grandiose delusions – believing they are someone famous, a celebrity, a martyr, or possess extraordinary abilities or importance.

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What are hallucinations?


Answer:
Hallucinations are false sensory experiences that occur without any external stimulus.


In schizophrenia, hallucinations are often:

• Auditory (hearing voices)

• Violent

• Distressing

• Frightening

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What is disorganised speech?


Answer:
Disorganised speech reflects disturbed thinking and difficulty communicating clearly.


It may include:

• Incoherent speech

• Frequent derailment (rapidly changing topics)

• Echolalia (repeating another person’s words)

• Word salad, where unrelated words are joined together without logical meaning

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What is disorganised or catatonic behaviour?


Answer:
Individuals with schizophrenia may display disorganised behaviour, making it difficult to perform normal daily activities.


Some individuals may also experience catatonic behaviour, which may involve:

• Unusual body postures

• Lack of movement

• Extreme agitation

• Unresponsiveness to the environment

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What are the major negative symptoms of schizophrenia?


Answer:


Anhedonia

• Inability to experience pleasure.

• Reduced enjoyment of normally pleasurable activities.

Alogia

• Impoverished speech.

• Limited verbal communication.

Avolition

• Lack of motivation or desire.

• Difficulty initiating or completing everyday tasks.

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How can you differentiate the positive and negative symptoms of schizophrenia?


Answer (Note Form):


Positive Symptoms (Presence of abnormal behaviours)

• Hallucinations

• Delusions

• Thought disorders

• Disorganised speech

• Disorganised behaviour

• Catatonic behaviour

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Negative Symptoms (Absence of normal functioning)

• Flattened emotional responses

• Alogia (poverty of speech)

• Anhedonia (inability to experience pleasure)

• Avolition (lack of motivation)

• Lack of initiative or persistence

• Social withdrawal

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What are the diagnostic features of schizophrenia?


Answer (Note Form):

• At least two characteristic symptoms must be present.

• Social or occupational functioning must be impaired.

• Symptoms must persist for at least one month.

• Disturbance must continue for at least six months.

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What are the characteristic symptoms required for diagnosis?


Answer (Note Form):

• Delusions

• Persecutory beliefs.

• Grandiose beliefs.

• Hallucinations

• Usually auditory.

• Often violent or distressing.

• Disorganised speech

• Incoherence.

• Frequent derailment.

• Echolalia.

• Word salad.

• Disorganised or catatonic behaviour

• Negative symptoms

• Anhedonia.

• Alogia.

• Avolition.

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Conclusion


Schizophrenia is diagnosed based on the presence of both positive and negative symptoms. Positive symptoms involve the addition of abnormal behaviours, such as hallucinations, delusions, disorganised speech, thought disorders, and catatonic behaviour, whereas negative symptoms involve the loss of normal functioning, including flattened emotions, alogia, anhedonia, avolition, lack of initiative, and social withdrawal. For a diagnosis, an individual must display at least two characteristic symptoms, experience social or occupational impairment, have symptoms present for at least one month, and show evidence of disturbance for a minimum of six months. Understanding the distinction between positive and negative symptoms is essential for accurately recognising and diagnosing schizophrenia.

Biological Psychology – Schizophrenia
What is schizophrenia?
Answer:
Schizophrenia is a severe and debilitating mental disorder that affects approximately 1% of the general population. It usually develops during late adolescence or early adulthood.
Although schizophrenia shares some symptoms with unipolar depression and bipolar disorder, its symptoms are generally:

• More severe.
• More obvious to other people.
• More disruptive to normal daily functioning.

Schizophrenia significantly affects an individual’s thoughts, emotions, behaviour, and ability to function in everyday life.


When does schizophrenia usually develop?
Answer:
Schizophrenia most commonly develops during:

• Late adolescence
• Early adulthood

This is the period when symptoms typically first become noticeable.


How does schizophrenia affect an individual’s daily functioning?
Answer:
Schizophrenia causes significant impairment in many aspects of life.
It can affect:

• Thinking
• Perception
• Emotions
• Behaviour
• Social relationships
• Education or employment
• Daily living skills

Because of these impairments, many individuals experience difficulties maintaining independence.


Why is schizophrenia associated with self-harm and suicide?
Answer:
Schizophrenia is associated with an increased risk of self-harm and suicide because hallucinations and delusions are often violent, frightening, or distressing.
These symptoms may:

• Cause overwhelming emotional distress.
• Increase feelings of fear and hopelessness.
• Lead some individuals to harm themselves.

Why may individuals with schizophrenia require hospitalisation?
Answer:
Due to the severity of symptoms, individuals with schizophrenia may require treatment under the Mental Health Act.
Hospitalisation may be:

• A single admission.
• Long-term (longitudinal).
• Repeated if symptoms remain severe or return after remission.

Hospital admission aims to:

• Stabilise symptoms.
• Protect the individual from harm.
• Provide appropriate treatment.

Are individuals with schizophrenia dangerous to others?
Answer:
Although there have been isolated cases where individuals with schizophrenia have harmed others, this is uncommon.
The majority of the risk is directed towards:

• The individual themselves, rather than other people.

Most people with schizophrenia are not violent, despite negative stereotypes often portrayed in the media.


Can schizophrenia be completely cured?
Answer:
Once an individual is diagnosed with schizophrenia, complete recovery is uncommon because of the underlying changes in brain structure and function associated with the disorder.
However:

• Appropriate treatment can greatly reduce symptoms.
• Many individuals experience periods of remission, during which symptoms become much less severe.
• Treatment can improve quality of life and daily functioning.

What is remission?
Answer:
Remission is a period during which the symptoms of schizophrenia become less severe or temporarily disappear. Although symptoms improve during remission, the disorder may still be present, and symptoms can return.


Why are the diagnostic criteria for schizophrenia controversial?
Answer:
The diagnostic criteria for schizophrenia have been criticised for lacking:

• Validity – whether the diagnosis accurately measures schizophrenia as a distinct disorder.
• Reliability – whether different clinicians consistently diagnose the same condition.

Some psychologists argue that schizophrenia is a “failed category” because:

• Many individuals with different symptoms receive the same diagnosis.
• The disorder may not be clearly distinguishable from other mental illnesses.
• The current diagnostic system may not accurately reflect the complexity of schizophrenia.

What are the key facts about schizophrenia?
Answer (Note Form):

• Affects approximately 1% of the population.
• Usually develops during late adolescence or early adulthood.
• Symptoms are generally more severe than those seen in depression.
• Causes major impairment in:
  • Thinking
  • Emotions
  • Behaviour
  • Daily functioning.
• Associated with:
  • Hallucinations
  • Delusions
  • Self-harm
  • Increased suicide risk.
• May require hospitalisation under the Mental Health Act.
• Most individuals are not dangerous to others.
• Symptoms improve with treatment and during remission.
• Complete recovery is uncommon due to underlying brain abnormalities.

What are the major debates surrounding schizophrenia?
Answer (Note Form):
Validity

• Do diagnostic criteria accurately identify schizophrenia?
• Does schizophrenia represent a distinct mental disorder?

Reliability

• Do different clinicians consistently diagnose schizophrenia in the same way?

“Failed Category” Debate

• Some psychologists argue schizophrenia includes many different symptom patterns.
• May not clearly distinguish between different mental disorders.
• Diagnosis may group together individuals with different underlying conditions.

Conclusion
Schizophrenia is a severe, chronic mental disorder that affects approximately 1% of the population and usually develops during late adolescence or early adulthood. It causes significant impairment in thinking, emotions, behaviour, and daily functioning, and is associated with hallucinations, delusions, self-harm, and an increased risk of suicide. Although some individuals may require hospitalisation under the Mental Health Act, most people with schizophrenia are not dangerous to others, with the greatest risk being to themselves. While complete recovery is uncommon because of underlying brain abnormalities, appropriate treatment and periods of remission can greatly reduce symptoms and improve quality of life. The diagnosis of schizophrenia remains controversial because questions continue to be raised about the validity, reliability, and whether schizophrenia should be regarded as a single disorder or a “failed category” containing a wide range of different conditions.

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Biological Psychology – Biological Treatments for Bipolar Disorder
What are the biological treatments for bipolar disorder?
Answer:
The biological treatments for the depressive episodes of bipolar disorder are similar to those used for major depressive disorder. However, additional treatments are needed to reduce the symptoms of mania. The main biological treatments include:

• Lithium
• Carbamazepine
• Antidepressants

These medications help stabilise mood, reduce manic episodes, and manage depressive symptoms.


Why is medication adherence difficult in bipolar disorder?
Answer:
Individuals with bipolar disorder may find it difficult to take their medication consistently because:

• They may forget to take their medication, especially during manic episodes.
• Some individuals choose not to take their medication because they miss the elevated mood and increased energy associated with mania.

Poor medication adherence increases the risk of relapse and recurrence of manic or depressive episodes.


What is Lithium?
Answer:
Lithium carbonate is a mood stabiliser commonly used to treat bipolar disorder.
It:

• Is more effective at treating mania than depression.
• Helps stabilise mood.
• Can reduce the cycle of manic episodes.
• Once mania is controlled, depressive symptoms often improve as well.

What are the side effects of Lithium?
Answer:
Although Lithium is effective, it may cause several side effects, particularly at high or toxic doses.
Common side effects include:

• Significant weight gain
• Increased thirst
• Hypothyroidism
• Motor incoordination
• Confusion

In cases of overdose, Lithium can cause:

• Medical coma

Regular monitoring of Lithium levels is important because the difference between a therapeutic and toxic dose is small.


What is Carbamazepine?
Answer:
Carbamazepine is a mood stabiliser that reduces the excitability of neurons.
It:

• Helps reduce mania.
• May also reduce depressive symptoms in some individuals.
• Stabilises mood by decreasing excessive neuronal activity.

What are the side effects of Carbamazepine?
Answer:
Carbamazepine may:

• Interact or compete with other medications and chemicals in the body.
• Cause anaemia, which reduces the number of healthy red blood cells.

Patients taking Carbamazepine require regular medical monitoring.


How are antidepressants used to treat bipolar disorder?
Answer:
The antidepressants used to treat major depressive disorder can also be prescribed to manage the depressive episodes of bipolar disorder.
Their purpose is to:

• Reduce depressive symptoms.
• Improve mood during depressive episodes.

However, antidepressants are often used carefully and usually alongside a mood stabiliser because they may increase the risk of triggering a manic episode if used alone.


Are pharmacological treatments addictive?
Answer:
Yes. Pharmacological treatments can lead to dependence with long-term use.
If medication is stopped too quickly, individuals may experience:

• Withdrawal symptoms
• Increased risk of relapse

Therefore, medications should only be discontinued gradually under medical supervision.


What are the main biological treatments for bipolar disorder?
Answer (Note Form):
Lithium

• Mood stabiliser.
• More effective for mania than depression.
• Helps break the bipolar cycle.
• Depressive symptoms often improve after mania is controlled.

Side effects:

• Weight gain
• Increased thirst
• Hypothyroidism
• Motor incoordination
• Confusion
• Toxic overdose may cause medical coma

Carbamazepine

• Mood stabiliser.
• Reduces neuronal excitability.
• Treats both mania and depression in some individuals.

Side effects:

• May interact with other medications.
• Can cause anaemia.

Antidepressants

• Used to treat depressive episodes of bipolar disorder.
• Same antidepressants used for major depression.
• Usually prescribed with a mood stabiliser to reduce the risk of triggering mania.

What are the important considerations when treating bipolar disorder?
Answer (Note Form):

• Patients may:
  • Forget medication during manic episodes.
  • Stop medication because they miss the elevated mood of mania.
• Pharmacological treatments may cause:
  • Dependence (addiction).
  • Withdrawal symptoms if stopped suddenly.
• Medication should always be taken as prescribed and discontinued gradually under medical supervision.

Conclusion
Biological treatment for bipolar disorder primarily involves mood stabilisers and antidepressants. Lithium is the most commonly used mood stabiliser and is particularly effective in controlling manic episodes, while Carbamazepine reduces neuronal excitability and may treat both mania and depression. Antidepressants are used to manage depressive episodes but are usually combined with mood stabilisers to reduce the risk of triggering mania. Although these medications are effective, they may cause significant side effects, including weight gain, hypothyroidism, anaemia, confusion, and, in severe cases, medical coma. Patients with bipolar disorder may also struggle with medication adherence because they miss the elevated mood associated with mania, and stopping medication too quickly can result in withdrawal symptoms and relapse. Therefore, careful monitoring and long-term treatment are essential for effective management of bipolar disorder.

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Biological Psychology – Biological Aetiology of Bipolar Disorder
What is the biological aetiology of bipolar disorder?
Answer:
The biological aetiology of bipolar disorder refers to the biological factors that contribute to the development of the disorder. These include genetics, neurotransmitter imbalances, hormonal changes, neurological abnormalities, and circadian rhythm disturbances.
The biological factors associated with major (unipolar) depression are also involved in bipolar disorder because bipolar disorder includes episodes of major depression. However, bipolar disorder is distinguished by the presence of both depressive and manic episodes.
In addition, the same non-biological factors associated with major depression (such as stressful life events, cognitive factors, personality, and environmental influences) can interact with biological vulnerability to contribute to bipolar disorder.


How do genetics contribute to bipolar disorder?
Answer:
Genetics play a significant role in bipolar disorder.
Research suggests that:

• Bipolar disorder has a stronger genetic influence than unipolar depression.
• Individuals may inherit a genetic predisposition from their parents.
• A possible dominant gene associated with bipolar disorder has been identified on chromosomes 4, 5, 18, 21, or X.

For comparison, studies of unipolar depression show:

• Monozygotic (identical) twins have a 46% chance of developing depression if their twin has been diagnosed.
• Dizygotic (fraternal) twins have a 20% chance of developing depression if their twin has been diagnosed.

These findings show that both disorders have an important genetic component, although the genetic influence appears to be stronger in bipolar disorder.


How do neurotransmitters contribute to bipolar disorder?
Answer:
Bipolar disorder is associated with imbalances in several neurotransmitters, many of which are also involved in unipolar depression.
These include:

• Serotonin
• Substance P
• Norepinephrine (noradrenaline)
• Acetylcholine
• Dopamine

These neurotransmitters regulate:

• Mood
• Emotions
• Motivation
• Neural communication

Abnormal levels contribute to both depressive episodes and manic episodes.
In addition:

• Decreased levels of 5-HIAA (a metabolite of serotonin) are associated with an increased risk of suicidal impulses during depressive episodes.

How do hormones contribute to bipolar disorder?
Answer:
The endocrine system also contributes to bipolar disorder.
Abnormal hormone levels occur during depressive episodes, particularly involving:

• Cortisol (the body’s primary stress hormone)
• Melatonin, which regulates sleep and circadian rhythms

Hormonal disturbances may worsen mood instability and contribute to depressive symptoms.


How does neurology contribute to bipolar disorder?
Answer:
Several neurological abnormalities have been linked to bipolar disorder.
Brain Structure
Individuals with bipolar disorder often have:

• Increased volume of the lateral ventricles.
• Increased volume of the globus pallidus.

Sodium Pump Dysfunction
Impairment of the sodium pump may result in:

• Reduced neural activity during depressive episodes.
• Increased neuronal hypersensitivity during manic episodes.

Hypothalamic–Pituitary–Adrenal (HPA) Axis
Abnormalities in the Hypothalamic–Pituitary–Adrenal (HPA) axis may develop because of stress and contribute to mood instability.
Neurological Similarities with Unipolar Depression
Like unipolar depression, bipolar disorder may also involve:

• Reduced activity of monoaminergic neurons, which release serotonin and norepinephrine.
• Increased activity in the amygdala and prefrontal cortex, areas involved in emotional regulation.
• Reduced numbers of glial cells within the subgenual prefrontal cortex.
• In some individuals, silent cerebral infarctions (strokes) may contribute to late-onset depressive symptoms.

How do circadian rhythms contribute to bipolar disorder?
Answer:
Disturbances in circadian rhythms (the body’s internal biological clock) are associated with bipolar disorder, particularly during depressive episodes.
Changes include:

• Shallow and fragmented sleep.
• Reduced slow-wave (delta) sleep.
• Increased Stage 1 sleep.
• Earlier and more frequent Rapid Eye Movement (REM) sleep.
• Seasonal influences on mood, such as Seasonal Affective Disorder (SAD).

Sleep disruption can increase the likelihood of both depressive and manic episodes.


How are bipolar disorder and unipolar depression biologically similar?
Answer:
Both disorders share many biological features, including:

• Genetic influences.
• Neurotransmitter imbalances.
• Hormonal abnormalities.
• Neurological changes.
• Circadian rhythm disturbances.
• Interaction between biological vulnerability and environmental stress.

The key difference is that:

• Unipolar depression involves depressive episodes only.
• Bipolar disorder involves both depressive and manic episodes.

What are the main biological factors associated with bipolar disorder?
Answer (Note Form):
Genetics

• Strong genetic predisposition.
• Greater genetic influence than unipolar depression.
• Possible dominant gene on:
  • Chromosome 4
  • Chromosome 5
  • Chromosome 18
  • Chromosome 21
  • Chromosome X
• Unipolar comparison:
  • Monozygotic twins → 46% concordance
  • Dizygotic twins → 20% concordance

Physiology – Neurotransmitters

• Imbalances of:
  • Serotonin
  • Substance P
  • Norepinephrine
  • Acetylcholine
  • Dopamine
• Low 5-HIAA associated with suicidal impulses.
• Neurotransmitter imbalances contribute to depression and mania.

Physiology – Hormones

• Abnormal endocrine activity.
• Increased abnormalities in:
  • Cortisol
  • Melatonin

Neurology

• Enlarged lateral ventricles.
• Enlarged globus pallidus.
• Sodium pump dysfunction:
  • Reduced neural activity → Depression.
  • Increased neural hypersensitivity → Mania.
• Abnormal Hypothalamic–Pituitary–Adrenal (HPA) axis.
• Reduced monoaminergic neuron activity.
• Increased blood flow and metabolism in:
  • Amygdala
  • Prefrontal cortex.
• Reduced glial cells in the subgenual prefrontal cortex.
• Silent cerebral infarctions may contribute to late-onset depression.

Circadian Rhythms

• Shallow, fragmented sleep.
• Reduced slow-wave (delta) sleep.
• Increased Stage 1 sleep.
• Earlier and more frequent REM sleep.
• Seasonal influences (e.g., Seasonal Affective Disorder).

What non-biological factors also contribute to bipolar disorder?
Answer:
Bipolar disorder is influenced by the same non-biological factors associated with major depression, including:

• Stressful life events.
• Cognitive factors.
• Personality traits.
• Social and environmental influences.

These factors interact with biological vulnerability to influence the onset and progression of bipolar disorder.


Conclusion
The biological aetiology of bipolar disorder involves the interaction of genetics, neurotransmitter imbalances, hormonal changes, neurological abnormalities, and circadian rhythm disturbances. Bipolar disorder has a strong genetic component, with possible genes located on chromosomes 4, 5, 18, 21, and X, and shares many biological mechanisms with unipolar depression, including abnormalities in serotonin, dopamine, norepinephrine, acetylcholine, Substance P, cortisol, melatonin, monoaminergic neurons, the amygdala, prefrontal cortex, and the Hypothalamic–Pituitary–Adrenal (HPA) axis. Sleep disturbances and seasonal changes also contribute to mood instability. The distinguishing feature of bipolar disorder is the presence of both depressive and manic episodes. Like unipolar depression, bipolar disorder is best explained using a biopsychosocial approach, recognising that biological vulnerability interacts with psychological, social, and environmental factors to produce the disorder.

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Biological Psychology – Non-Biological Aetiology of Unipolar Depression
What is the non-biological aetiology of unipolar depression?
Answer:
The non-biological aetiology of unipolar depression refers to the psychological, social, and environmental factors that contribute to the development of depression. Although biological factors are important, individuals do not exist in a biological vacuum. Depression usually develops through the interaction of both biological and non-biological influences.
Including both biological and non-biological explanations in discussions demonstrates critical thinking, evidence synthesis, and a balanced understanding of the disorder.


What non-biological factors contribute to unipolar depression?
Answer:
Several psychological and environmental factors are associated with the development of unipolar depression.
These include:

• Traumatic life events
• Personality traits
• Excessive worry
• Negative thought patterns
• Observational learning

These factors may interact with biological vulnerability to increase the likelihood of developing depression.


How do traumatic life events contribute to depression?
Answer:
Experiencing traumatic or stressful life events can trigger depressive episodes, particularly in individuals who are biologically vulnerable.
Examples include:

• Bereavement
• Relationship breakdown
• Loss of employment
• Serious illness
• Abuse or trauma

Stressful experiences can interact with biological predisposition to increase the risk of depression.


How do personality traits influence depression?
Answer:
Certain personality traits may make individuals more vulnerable to depression.
For example, people who are:

• Highly self-critical
• Pessimistic
• Emotionally sensitive
• Prone to anxiety

may be more likely to develop depressive symptoms when faced with stressful situations.


How do worry and negative thoughts contribute to depression?
Answer:
Persistent worry and negative thinking patterns can increase the risk of depression.
Examples include:

• Constant self-criticism.
• Feelings of hopelessness.
• Negative beliefs about oneself, the world, and the future.
• Repeated rumination about problems.

These cognitive patterns can maintain and worsen depressive symptoms.


How does observational learning contribute to depression?
Answer:
According to observational learning, individuals may learn depressive behaviours by observing others.
For example, a child who regularly observes depressive thinking or behaviour in parents or caregivers may learn similar coping styles and emotional responses.


Why is it important to consider both biological and non-biological factors?
Answer:
Depression cannot usually be explained by biological factors alone.
Psychologists should consider:

• Biological influences.
• Psychological influences.
• Social and environmental influences.

This demonstrates a biopsychosocial approach, recognising that multiple factors interact to influence mental health.


How can biological and environmental factors be compared?
Answer:
One way of evaluating depression is by comparing endogenous depression and reactive depression.
Endogenous Depression

• Mainly associated with biological or genetic factors.
• Develops without an obvious environmental trigger.

Reactive Depression

• Develops following a stressful or traumatic life event.
• Environmental factors play a greater role.

In reality, both forms usually involve an interaction between biological vulnerability and environmental stressors.


What questions should be considered when evaluating the causes of depression?
Answer:
When critically evaluating depression, psychologists should consider questions such as:

• Do biological factors predispose individuals to depression?
• Or do biological changes occur because of environmental stressors?
• How can researchers establish cause and effect?
• If no environmental cause is identified, does this mean that no environmental influence occurred?
• How do biological and environmental factors interact to produce depression?

These questions encourage a balanced and critical understanding of depression.


What are the main non-biological factors associated with unipolar depression?
Answer (Note Form):
Traumatic Life Events

• Bereavement.
• Relationship breakdown.
• Illness.
• Abuse.
• Stressful experiences.

Personality Traits

• Pessimism.
• High self-criticism.
• Emotional sensitivity.
• Anxiety-prone personality.

Worry

• Persistent worrying.
• Rumination.
• Difficulty controlling negative thoughts.

Negative Thoughts

• Hopelessness.
• Negative self-beliefs.
• Negative beliefs about the future.
• Self-criticism.

Observational Learning

• Learning depressive behaviours by observing others.
• Influence of parents, caregivers, or significant others.

What are the key evaluation points?
Answer (Note Form):

• Individuals do not exist in a biological vacuum.
• Biological and environmental factors interact.
• Compare:
  • Endogenous depression → Mainly biological.
  • Reactive depression → Triggered by environmental events.
• Consider:
  • Cause and effect.
  • Whether biology causes depression or results from stress.
  • Whether unidentified environmental influences may still exist.
• Demonstrates critical thinking and evidence synthesis.

Conclusion
The non-biological aetiology of unipolar depression includes traumatic life events, personality traits, excessive worry, negative thinking patterns, and observational learning. These factors interact with biological vulnerability to influence the development of depression. Rather than viewing depression as purely biological or purely environmental, psychologists adopt a biopsychosocial approach, recognising that both biological predisposition and life experiences contribute to the disorder. Critically evaluating depression also involves considering cause and effect, comparing endogenous and reactive depression, and recognising that the absence of an obvious environmental trigger does not necessarily mean that environmental influences were absent. This balanced perspective provides a more complete understanding of the causes of unipolar depression.

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Biological Psychology – Biological Aetiology of Unipolar Depression
What is the biological aetiology of unipolar depression?
Answer:
The biological aetiology of unipolar depression refers to the biological factors that increase an individual’s risk of developing the disorder. These factors include genetics, neurotransmitter imbalances, hormonal changes, neurological abnormalities, and disturbances in circadian rhythms.
You should be able to discuss each of these biological influences in detail when answering reports or essay questions on unipolar depression.


How do genetics contribute to unipolar depression?
Answer:
Research suggests that unipolar depression has a genetic component, meaning that a predisposition to the disorder can be inherited.
Evidence includes:

• Monozygotic (identical) twins have a 46% chance of developing depression if their twin has been diagnosed.
• Dizygotic (fraternal) twins have a 20% chance of developing depression if their twin has been diagnosed.

These findings suggest that genetics increase an individual’s vulnerability to depression, although environmental factors also play an important role.


How do neurotransmitters contribute to unipolar depression?
Answer:
Unipolar depression is associated with imbalances in several neurotransmitters, which are chemicals responsible for communication between neurons.
The neurotransmitters involved include:

• Serotonin
• Substance P
• Norepinephrine (noradrenaline)
• Acetylcholine
• Dopamine

These neurotransmitters help regulate:

• Mood
• Motivation
• Emotion
• Sleep
• Behaviour

A decrease in 5-HIAA, a metabolite of serotonin, has also been linked to an increased risk of suicidal impulses in individuals with depression.


How do hormones contribute to unipolar depression?
Answer:
The endocrine system releases abnormal levels of hormones during major depressive episodes.
The main hormones involved are:

• Cortisol – the body’s primary stress hormone.
• Melatonin – a hormone involved in regulating sleep and circadian rhythms.

Abnormal levels of these hormones contribute to mood disturbances, sleep problems, and other symptoms of depression.


How does neurology contribute to unipolar depression?
Answer:
Several neurological abnormalities have been linked to unipolar depression.
These include:
Reduced Monoaminergic Neuron Activity

• Decreased activity of monoaminergic neurons, which release serotonin and norepinephrine.
• Reduced neurotransmitter activity contributes to depressive symptoms.

Amygdala and Prefrontal Cortex
Research by Drevets (2001) found:

• A 50–75% increase in blood flow and metabolism within the amygdala and prefrontal cortex.
• The amygdala is involved in regulating emotions.
• The prefrontal cortex is involved in the expression and regulation of negative emotions.

Subgenual Prefrontal Cortex
Research by Öngür, Drevets and Price (1998) identified:

• A 24% decrease in glial cells within the subgenual prefrontal cortex in individuals with major depression.

Silent Cerebral Infarctions

• Silent cerebral infarctions (strokes) may contribute to the development of late-onset depression.

How do circadian rhythms and zeitgebers contribute to unipolar depression?
Answer:
Individuals with unipolar depression often experience disturbances in circadian rhythms, which regulate the body’s biological clock.
Common sleep changes include:

• Shallow and fragmented sleep.
• Reduced slow-wave (delta) sleep.
• Increased Stage 1 sleep.
• Earlier and more frequent Rapid Eye Movement (REM) sleep.

Environmental time cues (zeitgebers) can also influence depression.
For example:

• Seasonal changes may contribute to Seasonal Affective Disorder (SAD).

These disturbances affect mood, energy levels, and emotional wellbeing.


What are the main biological factors associated with unipolar depression?
Answer (Note Form):
Genetics

• Genetic predisposition can be inherited.
• Monozygotic twins:
  • 46% chance if one twin is diagnosed.
• Dizygotic twins:
  • 20% chance if one twin is diagnosed.

Physiology – Neurotransmitters

• Imbalances in:
  • Serotonin
  • Substance P
  • Norepinephrine
  • Acetylcholine
  • Dopamine
• Low 5-HIAA associated with suicidal impulses.

Physiology – Hormones

• Abnormal endocrine activity.
• Increased abnormalities in:
  • Cortisol
  • Melatonin

Neurology

• Reduced monoaminergic neuron activity.
• Reduced serotonin and norepinephrine transmission.
• Amygdala:
  • 50–75% increase in blood flow and metabolism.
• Prefrontal cortex:
  • 50–75% increase in blood flow and metabolism.
• Subgenual prefrontal cortex:
  • 24% decrease in glial cells.
• Silent cerebral infarctions (strokes) may cause late-onset depression.

Circadian Rhythms and Zeitgebers

• Shallow, fragmented sleep.
• Reduced slow-wave (delta) sleep.
• Increased Stage 1 sleep.
• Earlier and more frequent REM sleep.
• Seasonal influences.
• Seasonal Affective Disorder (SAD).

Why is it important to understand the biological factors of unipolar depression?
Answer:
Understanding the biological factors helps explain how genetics, neurotransmitters, hormones, brain function, and sleep regulation contribute to depression. However, these biological influences do not act alone. They interact with psychological, social, and environmental factors, making depression best explained using a biopsychosocial approach.


Conclusion
The biological aetiology of unipolar depression involves a combination of genetic predisposition, neurotransmitter imbalances, hormonal abnormalities, neurological changes, and disturbances in circadian rhythms. Individuals with a family history of depression have an increased genetic risk, while abnormalities in serotonin, Substance P, norepinephrine, acetylcholine, dopamine, cortisol, melatonin, and 5-HIAA contribute to the symptoms of depression. Neurological findings include reduced monoaminergic neuron activity, increased activity in the amygdala and prefrontal cortex, decreased glial cells in the subgenual prefrontal cortex, and the possible effects of silent cerebral infarctions. Sleep disturbances and seasonal influences further contribute to the disorder. Although these biological factors play a major role, unipolar depression is best understood using a biopsychosocial approach, recognising that biological vulnerability interacts with psychological, social, and environmental influences to produce the disorder.

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