A New Study Explores Why Multiple Diagnoses Are Common With Mental Illness

Much research has been invested in identifying susceptibility genes for schizophrenia and bipolar disorder. Several well-established linkages have emerged in schizophrenia.

“Relatives of people with schizophrenia have a greater risk of developing the illness, the risk being progressively higher among those who are more genetically similar to the person with schizophrenia,” wrote Colorado Recovery founder Richard Warner in his book The Environment of Schizophrenia.

“Evidence accumulated during the 20th century for a substantial genetic contribution to the etiology of both schizophrenia and bipolar disorder, with the genetic influences initially appearing to be largely distinct for each disorder. This reinforced the traditional concept of the Kraepelinian dichotomy, in which the two disorders were viewed as etiologically independent. The picture has now significantly changed to one of partial overlap in genetic influences, although many of the details about what is shared and independent remain to be elucidated. The dichotomy concept has thus been severely weakened but persists in diagnostic classification systems,” wrote Alastair Cardno and Michael Owen in their 2014 study on the genetic relationships between schizophrenia, bipolar disorder, and schizoaffective disorder.

Not only is there an overlap in genetic influences in schizophrenia and bipolar disorder, but more than half of patients diagnosed with one psychiatric disorder will also be diagnosed with a second or third mental illness in their lifetime. About a third have four or more.

A comprehensive new analysis of eleven major psychiatric disorders offers new insight into why comorbidities are the norm, rather than the exception. The study, published in the journal Nature Genetics, found that while there is no particular gene or set of genes driving an underlying risk for all of them, subsets of disorders—including bipolar disorder and schizophrenia; anorexia nervosa and obsessive-compulsive disorder; and major depression and anxiety—do share a common genetic architecture.

“Our findings confirm that high comorbidity across some disorders in part reflects overlapping pathways of genetic risk,” said lead author Andrew Grotzinger, an assistant professor in the Department of Psychology and Neuroscience at the University of Colorado at Boulder.

For the study, Grotzinger and colleagues at the University of Texas at Austin, Vrije Universiteit Amsterdam, and other collaborating institutions analyzed publicly available genome-wide association (GWAS) data from hundreds of thousands of people who submitted genetic material to large-scale datasets, such as the UK Biobank and the Psychiatric Genomics Consortium.

They found that 70 percent of the genetic signal associated with schizophrenia is also associated with bipolar disorder. That finding was surprising as, under current diagnostic guidelines, clinicians typically will not diagnose an individual with both.

The researchers also found that anorexia nervosa and obsessive-compulsive disorder have a strong, shared genetic architecture and that people with a genetic predisposition to have a smaller body type or low body mass index also tend to have a genetic predisposition to these disorders.

The eleven disorders included in the study were schizophrenia, bipolar disorder, major depressive disorder, anxiety disorder, anorexia nervosa, obsessive-compulsive disorder, Tourette syndrome, post-traumatic stress disorder, alcohol misuse, ADHD, and autism.

While more research is necessary to find out what the identified genes do, Grotzinger sees the results of his study as a first step toward developing therapies to address multiple disorders with one treatment.

“People are more likely today to be prescribed multiple medications intended to treat multiple diagnoses and in some instances, those medicines can have side effects,” he said. “By identifying what is shared across these issues, we can hopefully come up with ways to target them in a different way that doesn’t require four separate pills or four separate psychotherapy interventions.”

Colorado Recovery provides services for adults with serious mental illnesses that will stabilize their illness, minimize symptoms, improve functioning and enhance each person’s social inclusion, quality of life, and sense of meaning in life. We provide residential and outpatient treatment options for schizophrenia, bipolar, schizoaffective disorder, and other mental health conditions. Call us at 720-218-4068 to discuss treatment options for you or the person you would like to help.

Signs and Symptoms of Schizoaffective Disorder

Schizoaffective disorder is a mental health disorder that is marked by a combination of schizophrenia symptoms, such as hallucinations or delusions (psychosis), and mood disorder symptoms, such as depression or mania.

As the Mayo Clinic explains, there are two types of schizoaffective disorder: bipolar type, which includes episodes of mania, and sometimes major depression, and depressive type, which includes only major depressive episodes but no mania. 

Because of its hybrid character, schizoaffective disorder is not easy to diagnose correctly. “Many people with schizoaffective disorder are often incorrectly diagnosed at first with bipolar disorder or schizophrenia,” according to the National Alliance on Mental Illness. “Because schizoaffective disorder is less well-studied than the other two conditions, many interventions are borrowed from their treatment approaches.” 

Schizoaffective disorder falls under the schizophrenia spectrum and psychotic disorders category. Bipolar disorder, on the other hand, is a mood disorder. The key difference is that people living with schizoaffective disorder experience symptoms of psychosis independently of any mood episodes. In the case of bipolar disorder, symptoms of psychosis may occur during episodes of mania or depression but not otherwise.

Schizoaffective disorder is relatively rare, with a lifetime prevalence of only 0.3 percent. Sometimes other conditions such as psychotic depression, bipolar disorder I, schizophreniform disorder, or schizophrenia are mistaken for schizoaffective disorder. 

Treatments for schizoaffective disorder, bipolar disorder, and major depression with psychosis are fairly similar. If both manic episodes and depressive episodes are evident, the medications used are likely to include antipsychotic agents and mood stabilizers. If the illness only presents with depressive features and no manic symptoms at any time, then antidepressants are likely to be used.

Mania and depression are usually episodic and can be interspersed with long periods of complete remission of symptoms. If the illness is continuous, with no remission, then the diagnosis may be schizoaffective disorder.

As Nancy Lovering explained in a recent article on PsychCentral about bipolar and schizoaffective disorder, “it’s not possible to have both conditions at the same time. You’d either receive a bipolar disorder with psychotic features diagnosis or a schizoaffective bipolar type diagnosis. The difference would be if you experience mood episodes and psychosis at the same time as in bipolar disorder or if they appear independently at times.”

Colorado Recovery provides services for adults with serious mental illnesses that will stabilize their illness, minimize symptoms, improve functioning and enhance each person’s social inclusion, quality of life, and sense of meaning in life.  We provide residential and outpatient treatment options for schizophrenia, bipolar, schizoaffective disorder, and other mental health conditions. 

The treatment program at Colorado Recovery aims to empower adults with mental illness, and those who support them, with an unrelenting optimism for recovery, purposeful involvement in the community, and an enhanced sense of meaning in life. Call us at 720-218-4068 to discuss treatment options for you or the person you would like to help.