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Anhedonia had the highest expected influence in the most comprehensive network analysis, showing connections with negative and positive symptoms and functional domains.
Anhedonia is considered a central variable for patients with schizophrenia, possibly resulting in a new drug target.
A team, led by Samuel J. Abplanalp, PhD, Desert Pacific Mental Illness Research, Education and Clinical Center, Veterans Affairs Greater Los Angeles Healthcare System, utilized network psychometrics to identify differential associations and structural overlap between positive symptoms, negative symptoms, and functional domains in schizophrenia.
There is a need to better understand the boundaries and connections between positive symptoms, negative symptoms, and role functioning in patients with schizophrenia. There is currently limited empirical support for clear distinctions among these clinical areas.
In the cross-sectional study, the investigators applied network analysis and community detection methods to examine the interplay and structure of positive symptoms, negative symptoms, and functional domains in 979 patients with schizophrenia. The mean age of the patient population was 46 years and 67.7% (n = 663) of the population was male.
The study took place in 5 geographically distributed research centers in the US as part of the Consortium on the Genetics of Schizophrenia-2 from July 1, 2010, through January 31, 2014. The study population included clinically stable outpatients with schizophrenia or schizoaffective disorder. Patients with evidence of neurological or additional Axis I psychiatric disorders were excluded, as were patients with head injuries, strokes, and substance abuse issues.
The investigators sought measures of the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms, and the Role Functioning Scale and main outcomes of the expected influence, which assesses the relative importance of items to the network, defined as the association of an item with all others. Other outcomes included community detection and stability, defined as the presence of statistical clusters and their replicability.
The results show anhedonia had the highest expected influence in the most comprehensive network analysis, showing connections with negative and positive symptoms and functional domains.
In addition, positive symptoms had the lowest expected influence and community detection analyses showed the presence of 3 clusters corresponding to positive symptoms, negative symptoms and work functioning, functional domains, including independent living, family relationships and social network, and avolition anhedonia, and work functioning.
Hallucinations and delusions were replicated in 100% bootstrapped samples (n = 1000), and bizarre behavior and thought disorder replicated in 39% (n = 390) and 57% (n = 570), respectively.
On the other hand, negative symptoms and work functioning were replicated between 73% (n = 730) and 77% (n = 770) samples, respectively. The remain functional domains were in 94% (n = 940) of samples.
“The high centrality of anhedonia and its connections with multiple functional domains suggest that it could be a treatment target for global functioning,” the authors wrote. “Interventions for work functioning may benefit from a specialized approach that focuses primarily on avolition.”
The study, “Understanding Connections and Boundaries Between Positive Symptoms, Negative Symptoms, and Role Functioning Among Individuals With Schizophrenia,” was published online in JAMA Psychiatry.