Is schizophrenia common in twins?
Previous studies show that schizophrenia affects both members of identical twins in 41% to 61% of cases, but only 0 to 28% in non-identical twins. A previous pooling of twin studies has suggested that the "heritability" of schizophrenia is 81%.
The strongest risk factor for suicide is mental illness and studies show that mental illness is slightly more common among twins.
The concordance rates of schizophrenia for monozygotic twins have been found to be about 40 to 50%, and heritability estimates are around 80% 46,47.
July 2020) Folie à deux ('folly of two', or 'madness [shared] by two'), also known as shared psychosis or shared delusional disorder (SDD), is a collection of rare psychiatric syndromes in which symptoms of a delusional belief, and sometimes hallucinations, are transmitted from one individual to another.
Schizophrenia is caused by a chemical imbalance and other changes in the brain. It tends to run in families, but the environment may also play a role. While it affects men and women the same, symptoms tend to start earlier in men than in women. It's rare in childhood.
Therefore, twins personalities are changed for multiple reasons. They tend to be more dependent on others, especially peers. Twins can either be more social or less social (depending on how their relationship was) from having a twin. Twins look for closeness in their other relationships.
Classically, the bigger twin is the more physically dominant. It's basic human nature, and particularly applicable to boys as they hit puberty. It happens often with singleton siblings too… the older is bigger and enforces him/herself through physical dominance.
There is, certainly, a heritable component. A 2000 study of identical twins showed that when one member of the pair was narcissistic, there was a 77% chance the other would be too–something that was not true of fraternal twins, whose genes are no more similar than those of other siblings.
Conclusion: This study shows that there is an equal rate of bipolar disorder in twins and in singletons.
Of the twins who completed the diagnostic assessment, 16.4% were diagnosed with schizophrenia, 18% with bipolar disorder, 19.8% with major depression, and 45.7% were not affected. In 17% of cases, the presumptive diagnosis reported in the lifetime register changed status during the clinical interview.
What is a positive symptom of schizophrenia?
The symptoms of schizophrenia are usually classified into: positive symptoms – any change in behaviour or thoughts, such as hallucinations or delusions. negative symptoms – where people appear to withdraw from the world around then, take no interest in everyday social interactions, and often appear emotionless and flat.