![]() 18 Neither of these theories is inconsistent with the broader and prevailing view that schizophrenia is a neurodevelopmental disorder. 16īecause no discrete pathologic abnormality has emerged as an etiologic factor, schizophrenia may be an abnormality of neuronal connectivity 17 or of integrative neuronal circuits. They also have profound effects on the sleep electroencephalogram (EEG), diminishing REM sleep and non-REM (NREM) fast frequencies in the rat. 15 Metabotropic glutamate receptor agonists actually decrease brain excitability. 7,8,14 Agonists of metabotropic glutamate receptors (mGluRs) are currently being investigated as treatments for schizophrenia. Finally, the role of the excitatory neurotransmitter glutamate in the pathophysiology of schizophrenia is gaining greater credence in part because several of the recently identified schizophrenia susceptibility genes target glutamatergic transmission. Serotonin (5-hydroxytrypamine ) and norepinephrine have also been associated with the pathophysiology of schizophrenia because the potency of second-generation antipsychotics has been linked to 5-HT and alpha-adrenergic receptor blockade. The hypothesis holds that psychotic symptoms such as hallucinations and delusions are associated with hyperactivity of the mesolimbic DA system. Second, drugs such as amphetamines, which enhance DA activity, can cause a psychosis that mimics paranoid schizophrenia and can exacerbate schizophrenic symptoms. First, the potency of standard antipsychotic medication correlates with the amount of D 2 receptor blockade. ![]() The dopamine (DA) hypothesis of schizophrenia derived from two observations. For many years, the prevailing theory of schizophrenia has centered on the dopamine system. ![]() Functional imaging studies using positron emission tomography (PET) or regional cerebral blood flow have observed decreased metabolism in the frontal cortex (hypofrontality) and left hemisphere dysfunction.Ībnormalities of neurotransmitter systems have also been extensively investigated. These findings seem to be present at the onset of illness and cannot be attributed to progressive degeneration however, most findings are nonspecific and are observed in other psychiatric disorders. 11, 12 Regarding the latter, structural dysmorphologies have included enlarged lateral and third ventricles loss of total gray matter, frontal, and temporal lobe volume and a reduction in total brain size. 6, 12 Brain structural abnormalities have been found in postmortem studies and in living subjects by computed tomography (CT) and magnetic resonance imaging (MRI). The etiology of schizophrenia is poorly understood, but accumulating evidence has revealed a wide range of brain abnormalities. Benson, Irwin Feinberg, in Principles and Practice of Sleep Medicine (Fifth Edition), 2011 Pathogenesis
0 Comments
Leave a Reply. |