Reduction of blood platelet monoamine oxidase activity in schizophrenic patients on phenothiazines

Monoamine Oxidase B (MAO-B): A Target for Rational Drug Development in Schizophrenia Using PET Imaging as an Example

Monoamine oxidase B (MAO-B) is an important high-density enzyme involved in the generation of oxidative stress and central in the catabolism of dopamine, particularly in brain subcortical regions with putative implications in the pathophysiology of schizophrenia. In this chapter, we review postmortem studies, preclinical models, and peripheral and genetic studies implicating MAO-B in psychosis. A literature search in PubMed was conducted and 64 studies were found to be eligible for systematic review. We found that MAO-B could be identified as a potential target in schizophrenia. Evidence comes mostly from studies of peripheral markers, showing reduced platelet MAO-B activity in schizophrenia, together with preclinical results from MAO-B knock-out mice resulting in a hyperdopaminergic state and behavioral disinhibition. However, whether brain MAO-B is altered in vivo in patients with schizophrenia remains unknown. We therefore review methodological studies involving MAO-B positron emission tomography (PET) radioligands used to quantify MAO-B in vivo in the human brain. Given the limitations of currently available treatments for schizophrenia, elucidating whether MAO-B could be used as a target for risk stratification or clinical staging in schizophrenia could allow for a rational search for newer antipsychotics and the development of new treatments.

Knowledge, Attitude, and Practices Toward SARS-COV-2 Infection in the United Arab Emirates Population: An Online Community-Based Cross-Sectional Survey

Population's preventive practices and self-isolation is determinantal in the prevention and mitigation. This study explored the adult population's knowledge, attitude, and practice toward COVID-19 in UAE between the 4th and 14th of April 2020. The study was a community-based, cross-sectional study using a self-administered electronic questionnaire covering five different aspects: demographics, knowledge, practice, attitude, source, and trust of information, and a patient health questionnaire (PHQ-2) for depression screening. Results were analyzed using frequencies, cross-tabulation, and regression analysis. A total of 1,867 people responded to the survey. The mean age of participants was 36.0 years S.D. 10.8. Males were 19.3% and female (80.7%). Knowledge was significantly better in people with higher educational levels (B 0.17, P-value < 0.001), good preventive practice (B 0.12, P-value < 0.001), and higher perceived risk scores (B 0.053, P-value = 0.025). The best practice scores were shown by participants with older age (B 0.097, P-value < 0.05), with good knowledge (B 0.086, P-value < 0.05), were of non-UAE nationalities (B -0.08, P-value < 0.05), with jobs that cannot be practiced from home, military and health care employees (B -0.104, P-value < 0.05), had a personal history of contact with COVID-19 patients (B 0.053, P-value < 0.05), higher educational levels (B 0.052, P-value < 0.05), and a positive attitude toward taking a vaccine (B 0.088, P-value < 0.05). Depression risk was significantly higher in men, non-UAE nationals, in those with lower knowledge scores, and younger ages. The most followed practices were staying home, handwashing, avoiding social gatherings, limiting three people per vehicle, and avoiding public transportation. The least practiced measures were covering the face while sneezing or coughing and wearing masks. Although staying home was reported by 92.5% of participants, 22.6% mentioned that they were visited by more than two people and visited others in 18.4% during the last week. Social media was the source of information for 82.1% of the participants and most trusted doctors and healthcare providers. Depression risk was present in 18.9% of the participants, and most respondents (89%) agreed that SARS-COV-2 infection would be finally be successfully controlled. An encouraging finding is the willingness of two-third of the participants (64.5%) to take the COVID-19 vaccine and if it was developed, although it was very early in the pandemic. Only 14.6% said they would not take the vaccine, and 20.9% were not sure. The obtained results on knowledge and practices, although satisfactory, could be insufficient to prevent this pandemic from being contained. Therefore, we recommend the intensification of awareness programs and good practices. In addition, mental health is an area worth further studies.

Human platelet monoamine oxidase activity in health and disease: a review

The most readily available source of monoamine oxidase in man is the platelet, although only the B form of the enzyme is represented in this site. Platelet activity is higher in women than in men. The enzyme activity is generally stable and is partly under genetic control. There is some evidence that individuals with low activity have a higher psychiatric morbidity than those with high activity. Despite some negative studies, the consensus of publication dealing with schizophrenia, migraine, and alcoholism find that mean platelet monoamine oxidase activity in the patient group is lower than in the controls. Values are raised in unipolar depression. Technical differences, or patient or control group heterogeneity, might well account for the absence of unanimity in the literature. A considerable degree of overlap between patient and control values, whatever the clinical diagnosis, appears to be the standard finding. Apart from these neuropsychiatric disturbances, platelet monoamine oxidase activity is raised in megaloblastic anaemia and reduced in iron deficiency anaemia. Although altered enzyme activity values may be linked to abnormal platelet populations in some of the haematological disorders discussed, in general the causes of abnormal platelet monoamine oxidase activity are unknown.