Evaluation of IGF-1 as a novel theranostic biomarker for schizophrenia

Insulin-like Growth Factor 2 (IGF-2) and Insulin-like Growth Factor Binding Protein 7 (IGFBP-7) Are Upregulated after Atypical Antipsychotics in Spanish Schizophrenia Patients

“…In the case of SZ chronic patients, the majority of studies found that IGF-1 levels were statistically undifferentiated from healthy matched controls [ 30 , 31 , 32 , 33 ], and only one found that IGF-1 was downregulated in the SZ group [ 34 ]. Moreover, this downregulation was also observed in a responder group of SZ patients when compared not only against non-responders but also to healthy controls [ 35 ]. The nature of these contradictory results, as well as the clear relationship between the IGF signaling system and SZ, illustrates the importance of discriminating not only by stage, first vs. multiple, but also by responsiveness to treatment.…”

“…In the last decades, researchers have investigated the role of circulating IGF-1 protein levels in SZ [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Some studies found significantly higher levels of IGF-1 in a FE drug-naïve group of patients compared to healthy controls [ 26 , 27 ].…”

“…Nevertheless, this was not the case for IGFBP-3 nor IGFBP-7 [ 36 ]. In the case of IGF-1, some studies found a positive correlation between PANSS-N and PANSS general (PANSS-G) [ 35 ], which may be pointing in the opposite direction. Others found a negative correlation between IGF-1 and PANSS-G and PANSS total scores (PANSS-T) [ 31 ], while another found no significant associations between IGF-1 and any of the PANSS subscales [ 26 ].…”

“…Intriguingly, no study has found a relationship between a protein belonging to the IGF signaling system and the PANSS positive subscale (PANSS-P), which actually represents the most characteristic externalization of a psychotic episode [ 43 ]. Alternatively, one study observed a negative correlation between IGF-1 and a test that evaluates hallucinations [ 28 ], which can be considered closely related to PANSS-P. Other scales, such as the Clinical Global Impression (CGI) and the Brief Psychiatric Rating Scale (BPRS), have been previously used in an effort to correlate IGF changes with SZ behavioral outcomes [ 35 ]. In our case, we decided to add the Self-Assessment Anhedonia Scale (SAAS) [ 44 ], which has been used before in different studies to characterize anhedonia from a physical, mental, and emotional perspective [ 45 , 46 ].…”

Meta‐analysis of peripheral insulin‐like growth factor 1 levels in schizophrenia

“…Schizophrenia is a severe psychiatric disorder characterized by three categories of symptoms: positive (hallucinations, delusions, thought disorders), negative (avolition, social withdrawal, anhedonia, poverty of thought), and cognitive (impairment of executive functions, memory and speed of mental processing) (Marder & Cannon, 2019 ; Okamoto et al., 2021 ). It is a significant health issue that affects approximately 1% of the population and has substantial social and economic consequences, as patients are frequently unemployed and homeless (Charlson et al., 2018 ; Yesilkaya et al., 2021 ). Its cause appears to lie in a disruption in brain development caused by genetic and/or environmental factors (Owen et al., 2016 ), but due to its relative complexity and heterogeneity, the etiology and exact pathophysiological mechanisms are not yet completely understood (Hany et al., 2022 ).…”