Chapter 1
Chapter 1
A comprehensive review on schizophrenia: epidemiology, pathogenesis, diagnosis, conventional treatments, and proposed natural compounds used for management
Abstract
Schizophrenia is a complex, comprehensible mental condition that creates alienation from reality. Schizophrenia is a mental disease, which is marked by progressive deficits in working memory, attention, and executive functioning. Because the disease's etiology is unknown, current psychotherapy and pharmacological treatments merely treat symptoms and do not provide a cure. Schizophrenia symptoms include hallucinations, delusions, disorganized behavior, and lack of desire. Long-term use of antipsychotic (antagonists at multiple G-protein-coupled receptors) medicines for therapy has negative health consequences and discourages patients from taking regular medication. Ancient herbal therapies are regaining popularity in disease management due to their natural origins, less side effects, and cost-effectiveness. The various types of phytochemicals include alkaloids, glycosides, polyphenols, terpenes and terpenoids, phytosterols, cannabinoids, and carotenoids could be used as G-protein-coupled receptor antagonists. In this review, we documented the possibility of employing natural compounds as an alternative therapy to treat schizophrenia-related symptoms and cognitive impairments.
Introduction
Introduction
Schizophrenia is a serious debilitating disease of adults in every society, affecting around one to one point five percent of the global population. The incidence of schizophrenia is higher among males than females, with a ratio of one point four to one. Despite its long-standing recognition in psychiatric nosology, schizophrenia remains one of the most contested and conceptually complex diagnoses in mental health. Originating from Kraepelin's classification of dementia praecox and later reframed by Bleuler as "schizophrenia," the diagnosis has undergone significant transformation over the past century. Contemporary approaches have shifted from psychodynamic interpretations to more neurobiological and dimensional perspectives, yet the category continues to provoke critical debate. Concerns persist regarding its scientific validity, given the broad heterogeneity of symptoms, ranging from hallucinations and delusions to cognitive dysfunction and affective blunting, many of which overlap with other psychiatric conditions. Current diagnostic frameworks such as the DSM-five and ICD-eleven rely predominantly on symptom clusters rather than objective biomarkers, which raises questions about diagnostic precision, cultural applicability, and reliability across settings. Ongoing research into genetic, neuroimaging, and pathophysiological markers may refine future diagnostic approaches, potentially leading to more biologically grounded subtyping or a shift toward transdiagnostic frameworks.
Schizophrenia is the eighth costly disorder in the world. It is a syndrome that includes both positive and negative symptoms, as well as cognitive issues. Positive symptoms, including hallucinations and delusions, are the most prominent component of this illness. Negative symptoms include an inability to express emotions and indifference. Cognitive impairments occur before the manifestation of psychosis and can act as a better predictor of the disease. Unlike other degenerative diseases, it begins in early adulthood or late adolescence. Schizophrenia often develops in the second and third decades of life, however it can also affect the elderly. It raises the chance of several brain illnesses, including Parkinson's disease, autism, Alzheimer's disease, and multiple sclerosis. Schizophrenia results from a complex combination of genetic, dietary, microbial, and environmental variables. Several neurotransmitters, including dopamine, gamma aminobutyric acid, glutamate, serotonin, and noradrenaline, have important roles in the development and progression of schizophrenia. Furthermore, schizophrenia is caused by a combination of neuroinflammation, oxidative stress, cell signaling pathways, and aberrant immune system activation. Typical G-protein-coupled receptor antagonists medications have a higher affinity, stronger binding, and more inhibition of dopamine receptors than atypical G-protein-coupled receptor antagonists. However, atypical G-protein-coupled receptor antagonists medications are more effective than traditional G-protein-coupled receptor antagonists because they operate on dopamine, serotonin, and cholinergic receptors. Individual anti-schizophrenic medications have varying efficacy among patients. Atypical G-protein-coupled receptor antagonists are often more effective but have less side effects than traditional G-protein-coupled receptor antagonists. These synthetic medications have a variety of side effects, including hormonal changes, vertigo, tardive dyskinesia, obesity, infertility, neuroleptic malignant syndrome, drowsiness, and agitation. To avoid these drug-related issues, more effective and safer treatments are desperately needed.
Phytochemicals are natural compounds that provide a cost-effective, accessible, and valuable source of pharmaceuticals. Herbal remedies have been effectively used throughout human history. Humanity is turning to herbal remedies due to the uncertain efficacy and harmful health consequences of previously utilized medication for schizophrenia. Furthermore, progress in generating synthetic anti-schizophrenic medications remains glacial due to a variety of reasons such as the heterogeneity of schizophrenia phenotypes, confusing pathophysiology, pathological lesions, complex genetic modifications, and other risk factors. As a result of their vast range of biological actions, phytochemicals provide prospective and diversified alternatives to allopathic anti-schizophrenic medications. Schizophrenia is typically treated with traditional and atypical G-protein-coupled receptor antagonists, although these medications provide very modest benefits and have a wide range of side effects. Phytochemicals are a broad group of compounds that can be used as an alternative to standard allopathic treatments. This review aims to provide a comprehensive overview of schizophrenia, focusing on therapeutic targets and the mechanisms of natural compounds in its management. It also examines experimental models used to study schizophrenia and summarizes current conventional treatments, and clinical trials evaluating the efficacy of these natural treatments.