Attention deficit hyperactivity disorder and schizophrenia are two different mental disorders.
Attention deficit hyperactivity disorder (ADHD) is a chronic condition made up of behavioral symptoms that include inattentiveness, hyperactivity, and impulsiveness. ADHD affects around 6.4 million children in the United States and often continues into adulthood.
ADHD is more common in boys than girls but is equal among men and women, which suggests girls may be under-diagnosed during childhood. ADHD symptoms usually begin before age 12.
Schizophrenia is slightly more common in males than females. Symptoms may begin between ages 16 and 30.
Although ADHD and schizophrenia have many differences, there is also an overlap in symptoms and some similarities between the two disorders.
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Is there a link between ADHD and schizophrenia?
ADHD symptoms have been reported in individuals who develop schizophrenia in adulthood. Sometimes these symptoms are also seen in their children.
Some studies suggest a possible link between ADHD and schizophrenia.
Some possible links that have been found between ADHD and schizophrenia in studies include:
- ADHD is diagnosed in numerous children at genetic risk of schizophrenia
- People with schizophrenia often have symptoms of other psychiatric disorders in early adolescence and ADHD is one of the most frequently reported
- Childhood ADHD diagnosis may be more a better predictor of adulthood schizophrenia than depression
- Children with ADHD are at a high risk of developing a wide range of psychiatric disorders
- Children and teenagers with ADHD could be 4.3 times more likely to develop schizophrenia as adults than people without ADHD
- Stress-inducing factors may be associated with both ADHD and schizophrenia and may affect proper brain development of a child before birth
- ADHD and schizophrenia occurring together might be due to shared genetic factors
- Alternative forms of a gene that arise by mutation in people with schizophrenia are also found in ADHD.
Causes and risk factors
The cause of ADHD is not clear. Factors that may be involved include:
- Genetics: Research indicates that ADHD can run in families and genes may play a role
- Environment: Environmental factors, such as exposure to toxic materials
- Development: Problems with the central nervous system at important stages of development
The cause of schizophrenia is unknown. Factors that may increase the chances of developing schizophrenia include:
- Genetics: Schizophrenia can run in families. Different combinations of genes might make people more at risk from the condition.
- Brain development: Research shows that some individuals with schizophrenia have subtle differences in brain structure.
- Neurotransmitters. An imbalance between the chemical messengers in the brain - dopamine and serotonin - may be connected to schizophrenia. Research shows that drugs that alter the levels of these chemicals relieve schizophrenia symptoms.
- Pregnancy and birth complications: A low birth weight, premature labor, or lacking oxygen during birth are more likely to have happened to people with schizophrenia before or during their birth.
Risk factors for ADHD include:
- A family history of ADHD or another mental health disorder
- Exposure to certain substances while in the womb
- Lack of certain nutrients
- Psychosocial factors
- Premature birth or low birth weight
- Maternal stress during pregnancy
- Maternal smoking during pregnancy
- Alcohol and drug use during pregnancy
- Deficiency in folate, zinc, magnesium and polyunsaturated acids
Risk factors for schizophrenia include:
- A family history of schizophrenia
- Exposure to certain substance just before birth
- Nutritional deficits
- Infections during pregnancy
- Premature birth or low birth weight
- Deficiency in iron and vitamin D resulting in decreased choline during pregnancy
- An increase in immune system activity from inflammation or autoimmune disease
- Taking mind-altering drugs as teenagers or young adults
Similarities and differences
In addition to some of the shared risk factors for ADHD and schizophrenia above, a study found that autism, ADHD, bipolar disorder, major depression, and schizophrenia share the same genetic risk factors.
A variation in one of the genes they share is known to impact the brain circuitry involved in emotion, thinking, attention, and memory.
Symptoms of ADHD and schizophrenia
There are two categories of ADHD symptoms: inattentiveness and hyperactivity and impulsiveness.
ADHD symptoms relate to either inattentiveness or hyperactivity.
Symptoms of inattentiveness include:
- Short attention span, easily distracted
- Makes careless mistakes during activities
- Not appearing to listen when spoken to directly
- Unable to follow instructions and complete tasks
- Problems with organizing tasks
- Seeming forgetful or frequently losing things
- Avoiding tasks that require mental effort
Symptoms of hyperactivity and impulsiveness include:
- Unable to sit still, always fidgeting
- Unable to engage in leisure activities quietly
- Lacking concentration
- Excessive talking
- Interrupting or intruding on other people's conversations or activities
- Restlessness, excessive running, or climbing in inappropriate situations
- Acting without thinking
- Little to no sense of danger
There are three categories of schizophrenia symptoms: positive, negative, and cognitive.
Positive symptoms of schizophrenia include:
- Delusions, such as believing that they are being pursued by the government
- Paranoid thoughts
- Agitated or excessive body movements
- Agitated or inappropriate behavior
Negative symptoms of schizophrenia include:
- Social withdrawal
- Not caring about appearance and personal hygiene
- Reduced expression of emotion
- Losing interest and motivation
- Trouble concentrating, sleep changes, and feeling unable to leave the house
- Reduced conversation and speaking
Cognitive symptoms of schizophrenia include:
- Confused or disorganized thoughts
- Inability to understand information and make decisions
- Lacking focus and attention
- Problems with being able to use learned information immediately
Similarities and differences
In cases where the symptoms of ADHD and schizophrenia do not fall into the standard categories, the two conditions may be difficult to separate.
Schizophrenia does not typically have hyperactivity as a key feature, but then many people with ADHD are not hyperactive either.
People with schizophrenia often experience psychotic episodes which include hallucinations, delusions, and disturbed thoughts. While these symptoms are not typical of ADHD, around 10 percent of people with ADHD have psychotic symptoms.
The stimulant drugs that treat the condition may trigger these psychotic symptoms.
Thought disorders have also been shown in both schizophrenia and ADHD among teenagers.
Some people who are genetically at a high risk of schizophrenia meet the criteria for a diagnosis of ADHD.
Impaired attention is a defining trait of ADHD and is usually also seen in people with schizophrenia.
Tests and diagnosis
There is no specific test to diagnose ADHD. A doctor will ask about medical history, ask questions about symptoms, and conduct a medical exam to rule out other causes. The doctor will then compare symptoms with ADHD criteria and rating scales to make a diagnosis.
ADHD is usually diagnosed in childhood.
To diagnose schizophrenia, a doctor will ask about medical history, ask questions about symptoms, and ensure that symptoms are not due to medication, substance abuse, or another medical condition.
A doctor or mental health professional may perform a psychiatric evaluation and compare symptoms with diagnostic criteria for schizophrenia.
Schizophrenia is usually diagnosed in the late teenage years to the early 20s for men, and late 20s to early 30s for women.
Treatments for ADHD and schizophrenia
There is no cure for ADHD, but treatments can relieve many of its symptoms. Treatments may include:
ADHD and schizophrenia are treated with different types of medication.
- Stimulant drugs - these may boost and balance brain chemical levels
- Non-stimulant drugs - these take longer to work than stimulants, but can improve attention, focus, and impulsivity
- Psychotherapy - behavioral therapy can help people with ADHD manage and change their behavior
There is also no cure for schizophrenia, but medications and psychosocial therapy can help manage its symptoms. Treatments may include:
- Antipsychotic drugs - these may affect the brain chemical dopamine to control symptoms
- Psychosocial therapy - a combination of psychotherapy and social and work-related training to provide support, education, and guidance to people with schizophrenia
- Hospitalization - during periods of severe symptoms
- Electroconvulsive therapy - for people who are unresponsive to drug therapy
Similarities and differences
Although ADHD and schizophrenia share some of the same symptoms, they are treated differently.
ADHD is treated with stimulants that increase dopamine levels in the brain. Schizophrenia is treated with antipsychotics that block the effect of dopamine.
Symptoms of ADHD often improve with age, although some adults continue to experience problems. Most people with schizophrenia recover from their symptoms, although some will experience the occasional return of symptoms, known as a relapse.
A person with schizophrenia may also have ADHD, but there is no evidence that one condition causes the other. Research shows that there is a connection between ADHD and schizophrenia, but the exact link between the two needs more investigation.