Is Schizoaffective Disorder Genetic?

Schizoaffective disorder is a mental health condition in which a person experiences aspects of schizophrenia as well as aspects of a mood disorder, either bipolar disorder or major depressive disorder.

The disorder has two types, named for which mood symptoms are primarily present: bipolar type and depressive type.

It is experienced by approximately 0.3 to 0.8 percent of the world’s population, and its symptoms are responsible for a sizeable percentage of outpatient psychiatric clinic visits and inpatient psychiatric hospitalizations.

Symptoms of schizoaffective disorder fall into two categories: psychotic symptoms and affective symptoms.

• Psychotic symptoms include hallucinations of all the special senses (seeing, hearing, smelling, tasting, and touching), delusions, ideas of reference, severe paranoia, and thought disturbances.
• Affective symptoms refer to those of mood and energy, and can be further split into manic and depressive symptoms.
  • Manic symptoms include increased energy, impulsivity, a constant urge to talk, easy irritability, elevated mood, skipping from one idea to the next, and grandiose ideas about one’s role in the world.
  • Depressive symptoms include a decrease in energy, decreased concentration, an inability to experience pleasure, depressed mood, a sense of hopelessness, decreased libido, and suicidal thoughts.

The 5th edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders ( DSM-5) states that a schizoaffective disorder diagnosis is made when psychotic symptoms are present without mood symptoms at some point for at least two weeks, and that psychotic and affective symptoms are both present without meeting the criteria for schizophrenia, for bipolar disorder, or for major depressive disorder.

Though schizophrenia, bipolar disorder, and major depressive disorder have been, in one form or another, established diagnoses for more than 100 years, schizoaffective disorder is relatively new. There is still slight controversy about whether or not schizoaffective disorder is a variant of schizophrenia or of bipolar disorder, though all of the disorders appear to be genetically linked to each other. This is an important point, in part because scientists who are looking for genetic connections to these disorders must have a clear idea of what conditions they are looking for.

Like other mental health conditions, schizoaffective disorder has a significant genetic component. But what does having “a significant genetic component” mean? First, it can mean that the presence of certain genes, the number of copies of genes, or gene variants (also known as alleles) on an individual’s genetic code make it more likely that schizoaffective disorder develops. Second, it can mean that the presence of schizoaffective disorder in one’s family makes it more likely that another person in the family will experience it.

The answer is a resounding yes to the question is schizoaffective disorder genetic? However, there is one major caveat: it is unclear if the risk for developing schizoaffective disorder or related conditions stems from just one or a few genes, or if the risk is comprised from thousands of genes with each having a small effect. Recent research suggests that the latter is more likely, which makes the understanding of the genetic component of schizophrenia and schizoaffective disorder much more complicated.

The National Institute of Health states that the inheritance pattern of schizoaffective disorder is unclear. Its authors note that when a person has schizoaffective disorder, the risk for developing the disorder is greater in first-degree relatives—parents, siblings, and children—than it is for the rest of the population. People with schizoaffective disorder also have a higher chance of having a relative with depression, bipolar disorder schizophrenia, or other mental health conditions. Many studies show that schizoaffective disorder, like most mental health conditions, has a high rate of heritability, a complex term roughly meaning the proportion of genetic contribution to environment for any difference between two individuals.

The best data for answering questions about the genetic component of any condition tends to come from studies of twins. Identical twins come from the same maternal egg and thus share nearly 100 percent of their genetic material, so differences between them are usually attributed to differences in their environment, upbringing, or experiences. Fraternal twins, however, come from different maternal eggs and share about 50 percent of their genetic material, the same as any pair of siblings.

Research on twins shows that when schizoaffective disorder occurs in one identical twin, the chance that the other one will develop it is about 40-45 percent. In fraternal twins, the risk for developing it is around 5 percent. There is an important point and counterpoint to glean from such data. On one hand, the rate of development of schizoaffective disorder and identical twins is not 100 percent, which suggests that other factors besides genetics are likely to be significant in the cause of schizoaffective disorder. However, because identical twins share more genetics than fraternal twins, and they have higher rates of acquiring schizoaffective disorder if the other twin does, genetics play at least some role in acquiring schizoaffective disorder.

No matter how it develops, schizoaffective disorder is a manageable condition with effective medication, psychotherapy, and integrative therapy treatment options. Bridges to Recovery has treated schizoaffective disorder using an innovative, yet evidence-based, treatment approach for over 15 years. Contact us now to start your recovery journey today.