”Increases in broadband cortical electroencephalogram (EEG) power in the gamma band (30-80 Hz) range have been observed in schizophrenia patients and in mouse models of schizophrenia. They are also seen in humans and animals treated with the psychotomimetic agent ketamine. However, the mechanisms which can result in increased broadband gamma power and the pathophysiological implications for cognition and behavior are poorly understood. Here we report that tonic optogenetic manipulation of an ascending arousal system bidirectionally tunes cortical broadband gamma power, allowing “on-demand tests of the effect on cortical processing and behavior. Constant, low wattage optogenetic stimulation of basal forebrain (BF) neurons containing the calcium-binding protein parvalbumin (PV) increased broadband gamma frequency power, increased locomotor activity, and impaired novel object recognition. Concomitantly, task-associated gamma band oscillations induced by trains of auditory stimuli, or exposure to novel objects, were impaired, reminiscent of findings in schizophrenia patients. Conversely, tonic optogenetic inhibition of BF-PV neurons partially rescued the elevated broadband gamma power elicited by subanesthetic doses of ketamine. These results support the idea that increased cortical broadband gamma activity leads to impairments in cognition and behavior, and identify BF-PV activity as a modulator of this activity. As such, BF-PV neurons may represent a novel target for pharmacotherapy in disorders such as schizophrenia which involve aberrant increases in cortical broadband gamma activity.”
McNally JM et al: Optigenetic manipulation of an ascending arousal system tunes cortical broadband gamma power and reveals functional deficits relevant to schizophrenia. Mol. Psychiatry [Epub ahead of print, Jul 20, 2020; doi: 10.1038/s41380-020-0840-3.].
“…Evidence is mounting on the diverse neurological presentations associated with COVID-19. In a Rapid Review in The Lancet Neurology, Mark Ellul and colleagues1 nicely cover these findings, but we would like to emphasise the risk of associated stroke. As described in this Rapid Review, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might be more likely to cause thrombotic vascular events, including stroke, than other coronavirus and seasonal infectious diseases. In fact, a 7·6-fold increase in the odds of stroke with COVID-19 compared with influenza was recently reported….”
Fifi JT and Mocco J: COVID-19 related stroke in young individuals. Lancet Neurology 19(9): 713-715 (2020).
“….In this issue, Rhee and colleagues (1) draw on data collected as part of the National Ambulatory Medical Care Surveys (NAMCS) to provide an up-to-date and nationally representative description of recent trends in the pharmacotherapy of bipolar disorder. Extending from 1997 through 2016 and grouped into five 4-year epochs, the NAMCS survey data document several noteworthy changes in the outpatient care provided by psychiatrists in the United States, including trends in the medications they prescribe. These data are important for several reasons. The condition that Kraepelin called “manic-depressive insanity” in the late 19th century (2) continues to be one of the several classical forms of severe psychiatric illness that have helped to define modern psychiatric practice. As the 100th anniversary of publication of the final edition of Kraepelin’s text nears, theconditions now grouped together as bipolar disorders remain among the world’s most important public health problems because the illness often begins in adolescence or young adulthood; is characterized by episodic recurrences and, not infrequently, runs a chronic or rapid cycling course; is associated with high rates of vocational impairment and disability; and results in a significant reduction in life expectancy, both from an increased risk of suicide and from cardiometabolic comorbidities (3)….”
Thase ME: Charting Sea Changes in Outpstient Phsrmacotherapy of Bipolar Disorder.AmJ Psychiatry [Epub ahead of print, Aug. 1, 2020; https://doi.org/10.1176/appi.ajp.2020.2006084 ].
Canning CG et al.,: Virtual reality in research and rehabilitation of gait and balance in Parkinson disease. Nature Reviews Neurology 16: 409 –425 (2020).
Summary: “People with type 2 diabetes are at an increased risk of cognitive impairment and dementia (including Alzheimer’s disease), as well as subtle forms of cognitive dysfunction. Current diabetes guidelines recommend screening for cognitive impairment in groups at high risk and providing guidance for diabetes management in patients with diabetes and cognitive impairment. Yet, no disease-modifying treatment is available and important questions remain about the mechanisms underlying diabetes-associated cognitive dysfunction. These mechanisms are likely to be multifactorial and different for subtle and more severe forms of diabetes-associated cognitive dysfunction. Over the past years, research on dementia, brain ageing, diabetes, and vascular disease has identified novel biomarkers of specific dementia aetiologies, brain parenchymal injury, and cerebral blood flow and metabolism. These markers shed light on the processes underlying diabetes-associated cognitive dysfunction, have clear applications in current research and increasingly in clinical diagnosis, and might ultimately guide targeted treatment.”
Biessels GJ et al.: Understanding multifactorial brain changes in type 2 diabetes: a biomarker perspective. Lancet Neurology 19(8):699-710 (2020).
Introduction: “The World Federation of Neurology (WFN) celebrates World Brain Day on July 22, focusing on a different theme each year. In 2020, the theme is Move Together to End Parkinson’s Disease. The WFN works jointly with the International Parkinson and Movement Disorders Society and advocacy organisations worldwide. Parkinson’s disease has not been recognised as a risk factor for a severe form of COVID-19.Still, physical distancing, restrictions on outpatient services, medication supply issues, and other outcomes of the pandemic are probably affecting patients with Parkinson’s disease.
The global burden of Parkinson’s disease doubled between 1996 and 2016, mostly because of environmental risk factors and longer disease duration. This increase is expected to continue, with up to 12 million people predicted to have Parkinson’s disease in the next decade, attributable to the ageing of populations. For World Brain Day, we have defined five key messages (panel
Wijeratne T, Grisold W, Trenkwalder C, Carroll W: World Brain Day 2020: move together to end Parkinson’s disease. Lancet Neurology 19(8): p. 643 (2020).