Individuals often lack insight at this stage therefore, few will present directly to seek help for their psychotic symptoms. The first schizophrenic episode usually occurs during early adulthood or late adolescence. Potential organic causes of psychosis such as Parkinson's disease, multiple sclerosis, syphilis, AIDS, brain lesions, heavy metal toxicity, delirium, metabolic/endocrine disorders, and dementias including Alzheimer's disease, frontotemporal dementia, and Lewy body dementiasĪ thorough risk assessment must also be undertaken to determine the risk of harm to self and others. Differences in the frontal lobes and hippocampus are also seen, potentially contributing to a range of cognitive and memory impairments associated with the disease. There is a reduction in grey matter volume in schizophrenia, present not only in the temporal lobe but in the parietal lobes as well. There are also arguments that schizophrenia is a neurodevelopmental disorder based on abnormalities present in the cerebral structure, an absence of gliosis suggesting in utero changes, and the observation that motor and cognitive impairments in patients precede the illness onset.Ĭonversely, the disconnect hypothesis focuses on the neuroanatomical changes seen in PET and fMRI scans. Evidence showing exacerbation of positive and negative symptoms in schizophrenia by NMDA receptor antagonists insinuates the potential role of glutaminergic hypoactivity while serotonergic hyperactivity has also been shown to play a role in schizophrenia development. Other symptoms such as amenorrhea and decreased libido may be caused by elevated prolactin levels due to decreased availability of tuberoinfundibular dopamine as a result of blockage of the tuberoinfundibular pathway. Low mesocortical dopamine levels resulting from the mesocortical pathway are thought to elicit the negative symptoms of the disease. This dopamine hypothesis attributes the positive symptoms of the illness to excessive activation of D2 receptors via the mesolimbic pathway, while low levels of dopamine in the nigrostriatal pathway are theorized to cause motor symptoms through their effect on the extrapyramidal system. It postulates that four main dopaminergic pathways are involved in the development of schizophrenia. There are three main hypotheses regarding the development of schizophrenia. The neurochemical abnormality hypothesis argues that an imbalance of dopamine, serotonin, glutamate, and GABA results in the psychiatric manifestations of the disease. The diagnosis correlates with a 20% reduction in life expectancy, with up to 40% of deaths attributed to suicide. Over half of the patients have significant co-morbidities, both psychiatric and medical, making it one of the leading causes of disability worldwide. Despite a low prevalence, schizophrenia's global burden of disease is immense. Due to its relative complexity and heterogeneity, the etiology and pathophysiological mechanisms are not fully understood. Risk factors include birthing complications, the season of birth, severe maternal malnutrition, maternal influenza in pregnancy, family history, childhood trauma, social isolation, cannabis use, minority ethnicity, and urbanization. The diagnosis of schizophrenia is clinical, made exclusively after obtaining a full psychiatric history and excluding other causes of psychosis. Traditionally, symptoms have been divided into two main categories: positive symptoms, which include hallucinations, delusions, and formal thought disorders, and negative symptoms such as anhedonia, poverty of speech, and lack of motivation. Derived from the Greek 'schizo' (splitting) and 'phren' (mind) with the term first coined by Eugen Bleuler in 1908, schizophrenia is a functional psychotic disorder characterized by the presence of delusional beliefs, hallucinations, and disturbances in thought, perception, and behavior.
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