Schizophrenia
Schizophrenia is serious chronic brain disorder, affects approximately 1% of global population. Symptoms of schizophrenia is hallucinations, delusions, disorganized speech, decreased emotional expression, avolition, and cognitive impairment.
Impact of schizophrenia
Schizophrenia is the eighth costly disorder in the world.
It not only affects the health of person but also has economic and social impact, and the World Health Organization (WHO) considers it one of the top ten diseases in terms of overall impact on the world.
Impact of the disorder is different for each person, some people are more affected than others.
It affects the social life of the person, and they may become isolated from society. They may have difficulty in connecting with friends and family.
Many people are unable to continue their jobs due to symptoms, discrimination, or difficulties in managing daily routines.
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Symptoms
Schizophrenia is a major brain disorder that affects thinking, emotions, and social functioning.
It is not split personality, and split personality is associated with another condition called dissociative identity disorder, not schizophrenia.
Schizophrenia symptoms is classified into three types,
1. Positive
2. Negative
3. Cognitive
Positive Symptoms
Positive symptoms are symptoms that add abnormal experiences or behaviors to normal functioning. Thes are:
Delusions – Strong false beliefs that are not based on reality.
Hallucinations – Perceiving things that are not actually present, such as hearing voices, seeing things, or feeling sensations that others cannot perceive.
Hostility – Aggressive or suspicious behavior toward others.
Thought disorder – Disorganized thinking, where a person may speak in a confused or illogical way.
Motor impairment – Problems with movement, such as:
Catatonia – Reduced or abnormal movement, sometimes remaining motionless or rigid for long periods.
Psychomotor disturbance – Unusual movements, agitation, or slowed physical activity.
Negative Symptoms
Negative symptoms refer to the loss or reduction of normal emotional and behavioral functions.
These symptoms are often harder to recognize than positive symptoms but can cause serious long-term disability because they affect motivation, emotions, and social behavior.
Affect flattening – Reduced emotional expression; the person may show little facial expression, voice tone, or emotional reaction.
Alogia – Reduced speech or limited communication; the person may give very short answers or speak very little.
Avolition – Lack of motivation to start or continue activities such as work, studying, or personal care.
Anhedonia – Reduced ability to feel pleasure in activities that were previously enjoyable.
Asociality – Lack of interest in social interactions, leading to withdrawal from friends, family, or society.
Cognitive Changes
Cognitive symptoms affect a person’s thinking ability and mental processes. These symptoms may be subtle but must be noticeable enough for others to observe.
They involve difficulties in attention, memory, reasoning, and decision-making, which can affect daily functioning, learning, and work performance.
Attention problems – Difficulty concentrating or focusing on tasks.
Working memory impairment – Trouble holding and using information temporarily.
Executive function impairment – Difficulty planning, organizing, and making decisions.
Problem-solving difficulties – Reduced ability to analyze situations and find solutions.
Decrease in IQ – Some patients may show reduced cognitive performance over time.
Other related features mentioned
Thought disorder – Disorganized thinking and difficulty expressing ideas logically.
Negativism – Resistance to instructions or external suggestions.
Autism – Withdrawal into an inner world and reduced interaction with reality.
Intrapsychic ataxia – Lack of coordination between thoughts, emotions, and actions.
Schizophrenia Subtypes
1. Paranoid subtype
This type is mainly characterized by delusions (false beliefs) and hallucinations.
Patients may feel that others are deceiving, persecuting, or plotting against them.
2. Hebephrenic subtype (Disorganized type)
Person shows disorganized thinking and behavior.
Emotional responses are inappropriate or reduced, and the person often shows lack of goal-directed behavior.
3. Catatonic subtype
It is characterized by abnormal motor behavior.
Patients may show rigidity, immobility, agitation, tremors, or unusual postures, sometimes remaining in the same position for long periods (at least two weeks).
4. Simple subtype
Person may gradually lose motivation and interest in daily activities.
Negative symptoms such as social withdrawal and emotional dullness become more prominent over time.
Cause
Biopsychosocial Model
Schizophrenia does not occur because of only one reason. Instead, it develops due to the combined effect of several types of factors such as biological, psychological and social factors. This explanation is called the Biopsychosocial Model.
Biological factors– These are the physical or genetic factors such as family history, neurotransmitters imbalance in brain, structural or functional abnormalities on brain.
Psychological factors– These include mental and emotional influences, such as stress, trauma or emotional disturbances.
Social factors– These include family environment, social isolation, or substance abuse.
Risk Factors
Schizophrenia often begins earlier in life, typically during late adolescence or early adulthood.
The disorder most commonly develops around 20–30 years of age, although in some cases it can also appear in older adults.
Research suggests that schizophrenia may be linked with an increased risk or overlap with several neurological conditions, such as Parkinson’s disease, autism, Alzheimer’s disease and multiple sclerosis.
Genetic factors
1. Family history increases risk
People who have biological relatives with schizophrenia have a higher chance of developing the disorder. However, this increased risk is not seen in adopted relatives, which suggests that genetic factors are important rather than just shared environment.
2. Risk in first-degree relatives
First-degree relatives include parents, siblings, and children. If a person has a first-degree relative with schizophrenia, the risk increases to about 10%.
3. Risk when both parents have schizophrenia
If both parents have schizophrenia, the risk for their child increases significantly to about 40%.
4. Twin studies
Twin studies provide strong evidence for genetic influence.
Dizygotic Twins (twins from two different eggs) share about 50% of their genes, and the concordance rate for schizophrenia is about 10%.
Monozygotic Twins share 100% of their genes, and the concordance rate is about 40–50%.
Concordance means the probability that both twins will develop the disease if one twin has it.
The exact mode of genetic transmission of Schizophrenia is not fully understood, but many genes contribute to an individual’s susceptibility to the disorder.
Neurotransmitters (Biochemical factors)
Schizophrenia is not caused by a single biochemical problem. Instead, many biochemical pathways in the brain are involved, making it difficult to identify one specific abnormality responsible for the disease.
Scientists have found clues about these pathways mainly by observing how patients respond to psychoactive drugs (medications that affect brain function and behavior).
Several neurotransmitters (chemical messengers in the brain) are thought to play a role in the development of schizophrenia. The most important ones include dopamine, serotonin, norepinephrine, Gamma-aminobutyric acid (GABA), and Glutamate.
Effects of drugs on various Neurotransmitters
Dopamine Hypothesis of Schizophrenia
The dopamine hypothesis suggests that schizophrenia may be caused by abnormal or excessive activity of dopamine in the brain.
This idea developed from two main observations:
Drugs that block dopamine reduce symptoms- Certain antipsychotic drugs, such as Phenothiazines, block dopamine receptors in the brain.
When these drugs are used, psychotic symptoms like hallucinations and delusions decrease.
This suggested that too much dopamine activity might be involved in schizophrenia.
Drugs that increase dopamine can cause psychosis- Drugs like Amphetamine increase the release of dopamine. These drugs can produce paranoid psychosis in healthy individuals. They can also worsen symptoms in people with schizophrenia.
Glutamate Hypothesis of Schizophrenia
The glutamate hypothesis suggests that schizophrenia may be caused partly by reduced activity of glutamate neurotransmission in the brain, especially involving the NMDA receptor (a type of glutamate receptor).
Reduced glutamate receptor activity in the brain
Studies of postmortem brains of people with schizophrenia have shown abnormally low levels or reduced functioning of glutamate receptors, particularly NMDA receptors. This suggests that glutamate signaling may be impaired in the disorder.
Effects of certain drugs
Drugs such as Phencyclidine (PCP) and Ketamine block NMDA glutamate receptors (they are glutamate antagonists).
When these drugs are taken, they can produce symptoms similar to schizophrenia, including hallucinations and delusions.
They can also mimic cognitive problems seen in schizophrenia, such as difficulties with memory and attention.
Serotonin Hypothesis of Schizophrenia
The serotonin hypothesis suggests that excess or abnormal activity of serotonin in the brain may contribute to schizophrenia symptoms, including both positive symptoms (such as hallucinations and delusions) and negative symptoms (such as lack of motivation or reduced emotional expression).
Effect of certain antipsychotic drugs
Some antipsychotic medications, especially second-generation (atypical) antipsychotics, block serotonin receptors.
Role of clozapine- The drug Clozapine acts as a serotonin antagonist, meaning it blocks serotonin receptors (especially 5‑HT2A receptor).
Clozapine is very effective in reducing positive symptoms in many chronic schizophrenia patients. Its effectiveness suggests that serotonin pathways are involved in schizophrenia.
Other second-generation antipsychotics- Many modern antipsychotic drugs also block serotonin receptors along with dopamine receptors, which further supports the serotonin hypothesis.
Norepinephrine in the development of Schizophrenia
The neurotransmitter norepinephrine may be involved in the pathophysiology (biological mechanism) of schizophrenia.
There may be selective degeneration or damage of neurons in the norepinephrine-related reward system of the brain.
This damage can affect how the brain processes reward, motivation, and pleasure. Because of this, patients with schizophrenia may develop Anhedonia, which means:
Reduced ability to feel pleasure
Loss of interest in activities that were previously enjoyable.
Problems during pregnancy
Research suggests that complications during pregnancy or around the time of birth can slightly increase the chance that a child may develop schizophrenia in the future.
Maternal malnutrition
If a mother is malnourished during pregnancy, the baby’s brain development may be affected, which can increase the risk of schizophrenia later in life.
Viral infections during pregnancy
If a pregnant woman develops certain viral infections, it may interfere with the normal development of the fetal brain, increasing the likelihood of schizophrenia in the child.
Weather
Research has found that people born during winter months have a slightly higher risk of developing schizophrenia later in life. This pattern has been consistently observed in epidemiological studies, especially in the Northern Hemisphere.
However, winter birth itself is not the direct cause. Instead, it may act as an indicator of environmental factors that change with seasons.
Cannabis effect
Research suggests that heavy cannabis use during adolescence (ages 15–17) may increase the risk or accelerate the onset of psychosis, especially in people who are already genetically or biologically vulnerable to psychotic disorders.
Socio demographic factors
Schizophrenia usually begins between the late teenage years and the mid-30s.
Generally, in male, first psychotic episode usually appears in the early to mid-20s whereas, in female onset often occurs slightly later, usually in the late 20s.
The first 5–10 years of schizophrenia are often the most unstable or severe period, when symptoms may fluctuate and require treatment.
After this early phase, many patients experience long periods of relative stability, although most people do not completely return to their previous level of functioning.
Improvement of symptoms
Positive symptoms (hallucinations, delusions) are more likely to improve with treatment.
Negative symptoms and cognitive problems (lack of motivation, emotional blunting, memory or attention problems) are more persistent and harder to treat.
Race
Research shows that schizophrenia occurs in all racial and ethnic groups, and no clear biological difference in prevalence between races has been proven.
However, some studies have reported that schizophrenia is diagnosed more often in Black individuals than in White individuals.
Suicide and aggression in schizophrenia
People with the disorder have a much higher risk of suicide compared to the general population.
Up to 50% of people with schizophrenia may attempt suicide at least once during their lifetime.
Around 13% of all suicide deaths may occur among individuals with schizophrenia.
People with schizophrenia may sometimes experience strong hallucinations or delusions (false beliefs or hearing voices). Because of these symptoms, they may be more likely to use severe or violent methods when attempting suicide compared with patients with some other psychiatric disorders.
People with schizophrenia have more than eight times higher risk of suicide.
Individuals with schizophrenia also have a higher risk of dying from physical illnesses, especially cardiovascular disease (heart-related diseases) and respiratory disease (lung-related diseases)
Neuro-inflammation
Research suggests that in schizophrenia there may be persistent, low-grade activation of the immune system, particularly in the brain. This condition is often referred to as Neuroinflammation.
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