Is schizophrenia related to intelligence? Studies suggest those living with schizophrenia may have lower IQ scores, but more research is needed.
Schizophrenia is a chronic mental health condition that can affect a person’s thoughts, feelings, and behaviors.
But IQ scores aren’t the best judge to determine the connection between intelligence and schizophrenia.
People with high IQ scores are less likely to have schizophrenia than the general population.
If intelligence is best measured by IQ tests, a
Symbol coding and the ability to reason without words are usually the parts of the test that are most impaired. From this information, it could be said that a lack of intelligence is associated with schizophrenia.
Another measure of intelligence is cognitive function. This is a wide variety of different skills, including memory and executive function (a set of thoughts that help to control behavior).
If cognitive function is the best test of intelligence,
Some people with schizophrenia experience serious defects in most areas of functioning, but others will have minor effects in one area and more serious ones in others. And still more will have more minor effects overall.
While IQ tests can be said to measure some broad ability to reason, many IQ tests rely on areas of thinking that are impaired by schizophrenia.
Since those are also major parts of most IQ tests, it’s not easy to determine whether the person taking the test is being impaired in these areas by their schizophrenia or has what is considered an overall developmental impairment.
The lower scores seen in those affected by schizophrenia before their first symptoms appear to suggest that people who present with more cognitive deficits lead to a lower intelligence quotient than those without schizophrenia.
A study from 2015 suggested that those with schizophrenia who have “normal” intelligence scores may have had higher scores before the onset of schizophrenia. So it may also be the case that the onset of schizophrenia can lower an intelligence score.
The 2015 study mentioned above aimed to assess the symptoms of a select section of those with schizophrenia who had IQ scores of over 120 as compared to those who had lower scores.
They were measured in four categories of symptoms and on overall global levels of functioning. The group with higher intelligence had lower symptom scores and higher overall global functioning.
The only symptom group that was similar in both groups were the positive symptoms of schizophrenia: delusions, hallucinations, and unusual speech patterns.
In the “depressive” symptom group, high IQ individuals scored slightly higher than the control group, but only on overall levels and not on symptoms when tested.
The study’s conclusions were limited by the small sample size, only 29 men could be found with both schizophrenia and a score of over 120 on IQ tests. But the authors suggested that there may be a “superphrenia” group of high-IQ individuals who have different symptoms when experiencing episodes of psychosis.
Schizophrenia is typically treated with antipsychotic medication. It stands to reason that if schizophrenia has a negative effect on intelligence, treatment for schizophrenia may restore that intelligence.
Does antipsychotic treatment affect schizophrenia and intelligence? The short answer is “maybe.”
Many of these medications are no longer in use. The second group of antipsychotics, often called “atypical” antipsychotics, have fewer side effects than the first group.
Some initial observational studies showed that the use of these medications did in fact provide an increase in cognitive functioning and overall intelligence.
Because of the circumstances which they were conducted, these studies were considered limited, but later studies were conducted under randomized, double-blinded conditions.
Those studies also showed an increase in cognitive ability when atypical antipsychotics were used as opposed to other medications or with groups that had no medication at all.
When other medications were added that were supposed to improve cognition, there was no further effect.
The type of atypical antipsychotic didn’t seem to make a difference in the level of cognitive improvement. (One drug, clozapine, increased motor skills functioning, but not any other areas.)
So while treatment with some antipsychotics seems to increase intelligence, others reduce symptoms without that effect.
Other medications that are known to cause improved cognitive functioning had no effect when combined with those antipsychotics.
Schizophrenia is a condition that affects all areas of life, and that appears to include intelligence. Overall, people who live with schizophrenia have lower IQ scores than those who don’t experience the condition.
There are people who live with schizophrenia who have higher IQ scores, and they appear to have somewhat different symptoms than those with lower scores.
Antipsychotic medication can increase the cognitive functioning of many people who have schizophrenia.
The American Psychological Association offers resources on IQ tests.
The National Alliance for the Mentally Ill offers resources on support for schizophrenia.