Today our colleague from the Hospital Clínico Universitario de Valladolid, Dr. Óscar Martín, summarizes his literature review of the article: “Heterogeneity of Striatal Dopamine Function in Schizophrenia: Meta-analysis of Variance” (Stefan P. Brugger et al.; Biol Psychiatry, 2020).
Alterations of dopamine function in schizophrenia have been proven since the beginning of neuroleptic treatment in the middle of the 20th century. In recent years these numerous studies using PET and SPECT techniques have investigated these alterations, although the results have been heterogeneous. In this review and meta-analysis we have tried to verify the heterogeneity of these alterations, which is expected to be higher than that observed in the general population.
For this purpose, the variance of 65 studies of striatal dopaminergic striatal function in patients with schizophrenia (983) and in healthy control subjects (968) was analyzed. Data on dopamine synthesis, dopamine release capacity, dopamine D2/3 or dopamine transporter (DAT) receptor availability, and synaptic dopamine levels were investigated.
On the one hand, among their findings they found that both dopamine synthesis data and dopamine release capacity were higher in patients, although there was no great variability of data in patients or controls. On the other hand, the availability of dopamine D2/3 receptors and dopamine transporter (DAT) were not different in their mean values, although the dispersion of the data was greater in the patient group. Finally, synaptic dopamine levels were higher in the patient group, although with a large interindividual variability between patients.
Thus, the findings indicate significant heterogeneity of striatal dopamine function in schizophrenia. Elevated dopamine synthesis and release capacities may be features that affect most patients equally, however, other alterations such as D2/3 receptor availability, dopamine transporter (DAT) and synaptic dopamine levels may occur only in a subset of patients. This variability may contribute to the observed differences in treatment response and side effects observed in the patient group.