The first psychiatric pandemic: Encephalitis lethargica, 1917-27.

Finding a link between COVID-19 and subsequent psychiatric symptoms has resulted in renewed interest in the psychiatric sequelae of pandemics. The first such instance was apparently the encephalitis lethargica pandemic which arose around the time of the First World War, moving in the shadow of a repiratory virus pandemic. The epidemic of encephalitis lethargica (EL), or Von Economo's Disease, in the years 1917-27 was the first pandemic involving the central nervous system. It moved in some places in parallel with the Great Flu Pandemic but does not seem to have been caused by it. Unlike the coronavirus, pandemic EL affected children heavily, leading often to bizarre changes in character and personality. It often left sequelae lasting for decades in the form of postencephalitic Parkinsonism (PEP). Unlike the coronavirus, it had a high mortality of around 20 percent. Although encephalitis lethargica involved a number of systems, psychiatric morbidity was most prominent and entailed severe depression, mania, catatonia and psychosis. It ended without therapeutic or public-health measures; today, sporadic cases of EL continue to be reported. The hypothesis is that we can derive from the EL psychiatric pandemic certain lessons that might be useful in studying tardive COVID symptoms today.

Metabolic Topology of Neurodegenerative Disorders: Influence of Cognitive and Motor Deficits.

UNLABELLED: Parkinson disease with and without dementia (PDD and PD, respectively), dementia with Lewy bodies (DLB), and Alzheimer dementia (AD) traditionally have been viewed as distinct clinical and pathologic entities. However, intriguing overlaps in biochemical, clinical, and imaging findings question the concept of distinct entities and suggest a continuous spectrum in which individual patients express PD-typical patterns and AD-typical patterns to a variable degree. METHODS: Following this concept, we built a topological map based on regional patterns of the cerebral metabolic rate of glucose as measured with (18)F-FDG PET to rank and localize single subjects' disease status according to PD-typical (PD vs. controls) and AD-typical (AD vs. controls) pattern expression in patients clinically characterized as PD, PDD, DLB, amnestic mild cognitive impairment, and AD. RESULTS: The topology generally confirmed an indivisible spectrum of disease manifestation according to 2 separable expression patterns. The expression values derived from the first pattern were highly correlated with individual cognitive, but not motor, disability. The opposite was found for the corresponding expression values of the second pattern. CONCLUSION: The metabolic imaging analysis supports the notion that there is a continuous spectrum of neurodegeneration between AD and PD. Furthermore, PDD and DLB may in fact represent 1 overlapping disease entity, characterized by the presence of mixed neuropathology and only different by the time course.

Neuropsychiatric interpretations of postencephalitic movement disorders.

This study reviews the impact of encephalitis lethargica (EL) on concepts of behaviour and movement during the 1920s and 1930s. Clinicopathological correlations were imprecise but supported the role of subcortical structures in complex patterns of motor behaviour. This possibility challenged the widely assumed hegemony of the cerebral cortex. There was a perceived link between involuntary movements and reduced impulse control and also between parkinsonism and a defect in volition. Contemporary observers interpreted postencephalitic phenomena such as oculogyria in psychodynamic as well as in neurophysiological terms. EL also gave some support to the idea that neuroses such as obsessional neurosis and hysteria might have an organic basis. These speculations recently have acquired more credibility. The large amount of literature on EL and its sequelae could perhaps make further contributions to understanding the pathology of voluntary movement and action.

A controlled study of dementia in Parkinson's disease.

Tests of cognitive functions were carried out in a group of patients with Parkinson's disease and repeated after a three-year interval. Comparison was made with a control group drawn from a population of psychiatric patients, matched for age and sex. No differences in cognitive functions were found between the groups, either initially, or between those surviving for three years. Deaths among the index group included a high proportion of patients with cognitive impairment and there was an increasing prevalence and severity of dementia in the index group which exceeded that observed in the control group. Requirements for a methodologically sound study of dementia in Parkinson's disease are discussed.