Factors Underlying Abnormal Behaviour

Biological Factors

Biological Factors in Abnormal Behaviour

When we observe someone experiencing psychological distress—persistent anxiety, mood swings, hallucinations, or unusual behaviours—our first instinct might be to look for recent life events or environmental triggers. While these factors certainly matter, modern psychology has revealed a profound truth: the biological architecture of our brain and body plays a fundamental role in mental health. Understanding these biological underpinnings is crucial for developing effective treatments and reducing stigma around psychological disorders.

The Biological Foundation of Mental Health

The biological perspective examines abnormal behaviour through the lens of our physiology—our genes, brain chemistry, and neural structures. This approach doesn't suggest that mental disorders are "purely physical" or that psychological and social factors don't matter. Rather, it recognizes that our thoughts, emotions, and behaviours emerge from biological processes that can sometimes go awry.

Think of it this way: just as diabetes involves insulin regulation problems and asthma involves respiratory system dysfunction, psychological disorders often involve disruptions in brain function. This understanding has revolutionized mental health treatment and helped millions of people receive appropriate care.

Genetic Predispositions: The Blueprint of Vulnerability

Understanding Genetic Influence

Genes don't directly cause mental disorders—they create vulnerabilities. This is a critical distinction. Having a genetic predisposition means you carry certain genetic variations that increase your risk of developing a disorder, but environmental factors ultimately determine whether that disorder manifests.

{{VISUAL: diagram: illustration showing the diathesis-stress model with genetic vulnerability on one axis and environmental stressors on another, meeting to produce disorder development}}

Key Evidence from Research:

Family Studies reveal striking patterns. For example:

• If one parent has schizophrenia, children have approximately 13% risk (compared to 1% in general population)
• For bipolar disorder, having an affected first-degree relative increases risk by 10-15 times
• Major depression shows 2-3 times higher risk among relatives of affected individuals

Twin Studies provide even more compelling evidence:

• Monozygotic (identical) twins share 100% of their DNA
• Dizygotic (fraternal) twins share about 50% of their DNA
• If genetics play a role, identical twins should show higher concordance rates

Real-world example: Studies show that if one identical twin has schizophrenia, the other twin has approximately 48% chance of developing it—significantly higher than the 17% rate for fraternal twins. This difference highlights genetic contribution while also showing that genes aren't destiny (otherwise the rate would be 100%).

Adoption Studies help separate nature from nurture:

• Children adopted away from biological parents with disorders still show elevated risk
• This occurs even when raised in healthy environments, supporting genetic influence

The Polygenic Reality

Most psychological disorders are polygenic—influenced by multiple genes working together, not a single "mental illness gene." Each gene might contribute only a small effect, but collectively they significantly influence susceptibility.

{{VISUAL: diagram: visual representation of polygenic inheritance showing multiple genes from both parents contributing small effects that accumulate to create overall risk}}

Biochemical Imbalances: The Chemistry of Mind

Neurotransmitters and Mental Health

Our brain contains approximately 86 billion neurons that communicate through chemical messengers called neurotransmitters. These chemicals cross the tiny gaps (synapses) between neurons, transmitting signals that control everything from mood to memory to motor control.

When neurotransmitter systems malfunction—producing too much, too little, or responding abnormally—psychological symptoms can emerge.

Major Neurotransmitter Systems Involved:

1. Serotonin (5-HT)

• Functions: Mood regulation, sleep, appetite, impulse control
• Disorders linked to dysfunction: Depression, anxiety disorders, OCD, eating disorders
• Evidence: Selective Serotonin Reuptake Inhibitors (SSRIs) that increase serotonin availability effectively treat many of these conditions

2. Dopamine

• Functions: Reward processing, motivation, movement, attention
• Disorders linked to dysfunction:
  • Excess activity: Schizophrenia (particularly positive symptoms like hallucinations)
  • Deficiency: Depression, Parkinson's disease, ADHD
• Evidence: Antipsychotic medications work by blocking dopamine receptors

3. Norepinephrine (Noradrenaline)

• Functions: Alertness, arousal, stress response, attention
• Disorders linked to dysfunction: Depression, anxiety disorders, PTSD
• Evidence: Many antidepressants target both serotonin and norepinephrine systems

4. GABA (Gamma-Aminobutyric Acid)

• Functions: Primary inhibitory neurotransmitter; reduces neural excitability, promotes calm
• Disorders linked to dysfunction: Anxiety disorders, panic disorder
• Evidence: Anti-anxiety medications (benzodiazepines) enhance GABA activity

5. Glutamate

• Functions: Primary excitatory neurotransmitter; crucial for learning and memory
• Disorders linked to dysfunction: Schizophrenia, depression (treatment-resistant forms)

{{VISUAL: diagram: labeled diagram of a synapse showing neurotransmitter release, receptor binding, and reuptake mechanism with clear labels for presynaptic neuron, synaptic cleft, and postsynaptic neuron}}

Hormonal Influences

The endocrine system also affects mental health through hormones:

• Cortisol (stress hormone): Chronic elevation linked to depression and anxiety
• Thyroid hormones: Imbalances can cause depressive or manic symptoms
• Sex hormones: Estrogen and testosterone fluctuations influence mood (e.g., premenstrual dysphoric disorder, postpartum depression)

Brain Structure Abnormalities: Architecture and Function

Structural Differences in Psychological Disorders

Modern neuroimaging techniques (fMRI, PET scans, CT scans) have revealed that many psychological disorders involve measurable differences in brain structure and function.

Examples of Structural Abnormalities:

Schizophrenia:

• Enlarged ventricles (fluid-filled spaces in the brain)
• Reduced volume in hippocampus and prefrontal cortex
• Abnormalities in the thalamus (sensory relay station)
• These changes may explain cognitive deficits and information processing problems

Depression:

• Reduced hippocampal volume (linked to stress and elevated cortisol)
• Decreased activity in prefrontal cortex (involved in mood regulation)
• Hyperactivity in amygdala (emotional processing center)

Anxiety Disorders:

• Overactive amygdala (heightened fear responses)
• Reduced connectivity between prefrontal cortex and amygdala
• Prefrontal cortex normally regulates emotional responses; poor connectivity reduces this control

Obsessive-Compulsive Disorder:

• Abnormalities in the cortico-striatal-thalamic circuit
• Increased activity in orbitofrontal cortex and caudate nucleus
• Creates repetitive thought patterns and compulsive behaviors

{{VISUAL: diagram: side-view cross-section of human brain with labeled regions commonly affected in psychological disorders including prefrontal cortex, amygdala, hippocampus, thalamus, and ventricles}}

The Question of Causality

An important consideration: Do brain abnormalities cause disorders, or do disorders cause brain changes? Research suggests it's often bidirectional. Chronic stress and trauma can actually alter brain structure, while some structural differences appear to precede disorder onset, suggesting predisposition.

Integration: Biology in Context

Understanding biological factors doesn't mean ignoring psychological or social influences. The most accurate model is biopsychosocial, recognizing that:

• Biology creates vulnerabilities and influences symptom expression
• Psychology (thoughts, learning, coping styles) shapes how we respond
• Social factors (stress, relationships, culture) trigger or protect against disorders

For CBSE examination purposes, remember that biological factors provide essential explanations for abnormal behaviour, supported by extensive research evidence. Effective treatment often addresses biological aspects (medication) alongside psychological interventions (therapy) for optimal outcomes.