A significant proportion of people who test positive for COVID-19 have chemosensory deficits. However, the reported prevalence of these deficits in smell and taste varies widely, and the reason for the differences between studies is unclear. We determined the pooled prevalence of such chemosensory deficits in a systematic review and meta-analysis. We searched the COVID-19 portfolio of the National Institutes of Health for studies that reported the prevalence of smell and/or taste deficits in patients diagnosed with COVID-19. One-hundred-four studies reporting on 38,198 patients qualified and were subjected to a systematic review and meta-analysis. Estimated random prevalence of olfactory dysfunction was 43.0%, of taste dysfunction was 44.6%, and of overall chemosensory dysfunction was 47.4%. We examined the effects of age, gender, disease severity, and ethnicity on chemosensory dysfunction. Prevalence of smell and/or taste dysfunction decreased with older age, male gender, and with disease severity. Ethnicity was highly significant: Caucasians had a three times higher prevalence of chemosensory dysfunctions (54.8%) than Asians (17.7%). The finding of geographic differences points to two, not mutually exclusive causes. A virus mutation (D614G) may cause differing infectivity, while, at the host level, genetic, ethnicity-specific variants of the virus-binding entry proteins may facilitate virus entry in the olfactory epithelium and taste buds. Both explanations have major implications for infectivity, diagnosis and management of the COVID-19 pandemic.

A significant fraction of people who test positive for COVID-19 have chemosensory deficits. However, the reported prevalence of these deficits in smell and/or taste varies widely, and the reason for the differences between studies is unclear. We determined the pooled prevalence of such chemosensory deficits in a systematic review. We searched the COVID-19 portfolio of the National Institutes of Health for all studies that reported the prevalence of smell and/or taste deficits in patients diagnosed with COVID-19. Forty-two studies reporting on 23,353 patients qualified and were subjected to a systematic review and meta-analysis. Estimated random prevalence of olfactory dysfunction was 38.5%, of taste dysfunction was 30.4% and of overall chemosensory dysfunction was 50.2%. We examined the effects of age, disease severity, and ethnicity on chemosensory dysfunction. The effect of age did not reach significance, but anosmia/hypogeusia decreased with disease severity, and ethnicity was highly significant: Caucasians had a 3-6 times higher prevalence of chemosensory deficits than East Asians. The finding of ethnic differences points to genetic, ethnicity-specific differences of the virus-binding entry proteins in the olfactory epithelium and taste buds as the most likely explanation, with major implications for infectivity, diagnosis and management of the COVID-19 pandemic.

The prevalence of chemosensory dysfunction in patients with COVID-19 varies greatly between populations. It is unclear whether such differences are due to factors at the level of the human host, or at the level of the coronavirus, or both. At the host level, the entry proteins which allow virus binding and entry have variants with distinct properties, and the frequency of such variants differs between ethnicities. At the level of the virus, the D614G mutation enhances virus entry to the host cell. Since the two virus strains (D614 and G614) coexisted in the first six months of the pandemic in most populations, it has been difficult to distinguish between contributions of the virus and contributions of the host for anosmia. To answer this question, we conducted a systematic review and meta-analysis of studies in South Asian populations when either the D614 or the G614 virus was dominant. We show that populations infected predominantly with the G614 virus had a much higher prevalence of anosmia (pooled prevalence of 31.8%) compared with the same ethnic populations infected mostly with the D614 virus strain (pooled anosmia prevalence of 5.3%). We conclude that the D614G mutation is a major contributing factor that increases the prevalence of anosmia in COVID-19, and that this enhanced effect on olfaction constitutes a previously unrecognized phenotype of the D614G mutation. The new virus strains that have additional mutations on the background of the D614G mutation can be expected to cause a similarly increased prevalence of chemosensory dysfunctions.

IntroductionAlthough certain psychedelic agents may soon gain federal approval for use in treating specific psychiatric conditions, the utilization of such therapies in clinical practice will depend largely on the attitudes of healthcare providers. Therefore, this study assesses the current attitudes, knowledge, exposure, and acceptance of psychedelics and psychedelic-assisted therapies amongst medical students.MethodsIn fall semester of 2022, surveys were emailed to 580 medical students attending medical institutions in the state of Nevada in the United States. Utilizing knowledge and attitude items from previously published studies, the survey collected demographic data and assessed student attitudes with five-point Likert-scale variables. Data was analyzed using summary statistics and Kruskal-Wallis tests for differences in mean survey scores (i.e., attitudes towards psychedelics) based on demographic factors.Results132 medical students participated in the survey (22.7% response rate). Medical students demonstrated overall positive attitudes towards psychedelics, lack of knowledge regarding psychedelics, and uncertainty towards neurocognitive risks of psychedelics. Overall, 78.6% of students agreed that psychedelics have therapeutic potential, while 95.2% agreed that psychedelics deserves further research in assessing this potential. Additionally, there was no statistically significant effect of demographic variables, including age, sex, and level of training, on attitudes.DiscussionAlthough students are overall curious and optimistic about psychedelics, they demonstrate a lack of knowledge regarding recent research efforts. As the field of psychiatry prepares to implement psychedelics and psychedelic-assisted therapies, education and awareness of such agents should be initiated early on in medical clinical training.

The prevalence of chemosensory dysfunction in patients with COVID-19 varies greatly between populations. It is unclear whether such differences are due to factors at the level of the human host, or at the level of the coronavirus, or both. At the host level, the entry proteins which allow virus binding and entry have variants with distinct properties, and the frequency of such variants differs between ethnicities. At the level of the virus, the D614G mutation enhances virus entry to the host cell. Since the two virus strains (D614 and G614) co-existed in the first six months of the pandemic in most populations, it has been difficult to distinguish between contributions of the virus and contributions of the host for anosmia. To answer this question, we conducted a systematic review and meta-analysis of studies in South Asian populations when either the D614 or the G614 virus was dominant. We show that populations infected predominantly with the G614 virus had a much higher prevalence of anosmia (pooled prevalence of 31.8%) compared with the same ethnic populations infected mostly with the D614 virus strain (pooled anosmia prevalence of 5.3%). We conclude that the D614G mutation is a major contributing factor that increases the prevalence of anosmia in COVID-19, and that this enhanced effect on olfaction constitutes a previously unrecognized phenotype of the D614G mutation. The new virus strains that have additional mutations on the background of the D614G mutation can be expected to cause a similarly increased prevalence of chemosensory dysfunctions.