When most people hear the word “schizophrenia,” they think about patients who experience hallucinations and delusions, unable to distinguish reality from the buzzing voices inside their heads. In truth, however, schizophrenia is far more complicated.
Highly variable symptoms
Schizophrenia is a complex disorder experienced by different people in different ways. Besides the more recognizable psychotic symptoms – somewhat ironically dubbed “positive” symptoms – people with schizophrenia can also demonstrate so-called “negative” symptoms, such as difficulties with motivation, emotions and socialization. Patients can also experience cognitive symptoms, such as trouble with working memory, task switching and organizing complex activities. The presence and intensity of the symptom types can vary significantly from person to person.
Because the symptoms associated with schizophrenia are so variable, some researchers have theorized that schizophrenia is not one disorder, but rather a spectrum of disorders with distinct subtypes.
Distinguishing schizophrenia subtypes
A study released in March of this year further lends evidence to the theory that schizophrenia is a spectrum of disorders. This study, entitled “Further Neuroimaging Evidence for the Deficit Subtype of Schizophrenia: A Cortical Connectomics Analysis,” was conducted by the Centre for Addiction and Mental Health (CAMH) in Canada and published in the journal JAMA Psychiatry. Researchers recruited schizophrenia patients who demonstrated profound negative symptoms – for instance, difficulties with social isolation, motivation and mood – as well as patients who did not have these symptoms.
To evaluate the neural characteristics of both groups, the researchers used a unique brain imaging approach known as network analysis. Network analysis allows the researchers to determine which areas in the brain are highly connected with other areas in the brain. If patients with severe negative symptoms have a different connectivity pattern than patients without these severe symptoms, then it would be reasonable to assume that the two groups have different schizophrenia subtypes.
Sure enough, patients who had severe negative symptoms had different neural connectivity than patients without these symptoms.
Potential targets for therapy
Researchers have estimated that approximately 1 in 5 patients with schizophrenia have severe negative symptoms. Given that an estimated 3.5 million adults are living with schizophrenia in the United States, this means that over 400 thousand people in the country are suffering from this form of schizophrenia – that’s enough people to fill more than 8,000 school buses.
Despite the prevalence of these negative symptoms, however, currently no therapies target them. Medication also fails to target these symptoms – antipsychotics are only capable of treating hallucinations and delusions. So what are patients with severe negative symptoms supposed to do?
By determining what distinguishes one schizophrenia subtype from another, researchers might be able to identify potential targets for therapy. Which brain areas are associated with severe negative symptoms? Which are associated with severe positive symptoms? When people with schizophrenia struggle with decision-making, what precisely is their brain doing? Do all of the symptoms associated with schizophrenia originate from the same place? Can schizophrenia be cured with one medication, or will clinicians need to use multiple medications that target multiple cellular mechanisms?
As with many mental disorders, understanding the neural origins of schizophrenia remains a work in progress. One thing is certain, however: Distinct subtypes of schizophrenia do exist, and if clinicians treat all subtypes the same, they are destined to fail.