Research Roundup is a monthly public service of the Office of Research and Public Affairs. Each edition describes a striking new data point about severe mental illness and summarizes recently published research reports or developments. This month’s roundup dives deep into some science behind severe mental illness.
DATAPOINT of the month
86 billion neurons in the human brain
There are 86 billion neurons in the human brain. Neurons are a type of cell that comprise the brain, which are not found in any other part of the body and come in various different forms. Some neurons excite or turn on other neurons, while others turn them off. Neurons are connected together at synapses to form complex signaling pathways throughout the brain and signal through molecules called neurotransmitters. The complex signaling pathways in our brain are what allow us to form memories, recognize faces and experience emotions.
RESEARCH of the month
Glutamate and positive symptoms in early-stage psychosis
Clinical high risk for psychosis is the early stage before developing a psychotic disorder and provides an important opportunity for interventions prior to the development of an illness. If we can understand the mechanisms by which people who are at clinical high risk for psychosis and go on to develop schizophrenia are different than those with clinical high risk but who do not develop schizophrenia, it will provide insight into how the disease development may be prevented.
Recent research published in JAMA Psychiatry by authors from Columbia University discovered key differences between converters and non-converters of individuals with clinical high risk for psychosis in their hippocampal glutamate levels and positive symptom severity before their conversion to psychosis. Glutamate is a neurotransmitter in the brain that aids in signaling from one cell to another.
Individuals with clinical high risk who did not develop psychosis had an inverse association between glutamate levels in their hippocampus region of the brain and positive symptom severity, meaning as glutamate levels increased, their pre-illness positive symptom severity decreased. Individuals with clinical high risk for psychosis who did convert into a psychotic disorder had the opposite relationship: as glutamate levels increased, positive symptom severity increased prior to developing illness-level psychosis.
According to the authors, these results suggest that converters and nonconverters differ in their basic pathophysiology of pre-illness psychotic symptoms. Reducing glutamate levels may be a therapeutic target to prevent converters to develop psychosis.
MicroRNA, synapses and schizophrenia
MicroRNA is a type of cellular genetic material that does not code particular genes but has an important role in the development and function of brain signaling. A particular type of microRNA, miR-936, has been shown to be increased in the dorsoloateral prefrontal cortex brain region of individuals with schizophrenia, however the significance of that was, until recently, unknown.
Scientists are beginning to discover the role miR-936 plays in brain development and what this means for schizophrenia. Research published in Schizophrenia Bulletin by researchers from the National Institute of Health suggests that miR-936 is found in glutamate neurons and plays a role in reducing the number of excitatory synapses in the brain. The results indicate that the higher levels of miR-936 in particular regions of the brain may in part underlie the brain signaling issues in individuals with schizophrenia, including reduced activation and weakening of glutamate excitatory signaling.
The gut microbiome and severe mental illness
There is evidence to suggest that alterations to the gut microbiome, or the microorganisms and bacteria that naturally exist in our digestive tracts, are associated with certain psychiatric disorders. In fact, variations in the composition of microbiomes have been proposed for use as potential biomarkers for mental illnesses, including schizophrenia and bipolar disorder.
A new meta-analysis published in JAMA Psychiatry by researchers from Kings College of London suggests that individuals with bipolar disorder and schizophrenia have higher amounts of pro-inflammatory bacteria in their gut compared to those without these illnesses. As scientists continue to research the impact of our gut microbiome on our immune systems and the association of immune system alterations and inflammation with psychiatric disorders, the connection between the gut microbiome and psychiatric illnesses will become clearer.
