To the Editor Dr Verma and colleagues1 applied multimodal neuroimaging to 40 individuals employed at the US embassy in Cuba between 2016 and 2018, some of whom had cognitive, balance, oculomotor, headache, and mood symptoms following possible directional phenomena exposure. We are concerned about some limitations of the study.
One concern is the choice of controls. To show that directional phenomena might be responsible for brain changes in this cohort, another unexposed group of patients with the same symptoms, such as those found in a general neurology clinic, should have been selected, rather than demographically similar healthy individuals. Details on the comorbidities of the controls and how they were recruited were lacking. Additionally, of the 40 patients studied, 10 did not endorse exposure to directional phenomena, in 20 individuals the nature of the symptoms was not well described, and 6 had no clinical information. Other potentially confounding factors were not adequately considered, including an average delay of 190 days between exposure and imaging, medication effects, and individual differences in IQ or psychiatric comorbidities.