BDNF and post-traumatic stress disorder: Mitochondrial dysfunction and subsequent lactate accumulation in the brain, which can trigger panic attacks and flashbacks in PTSD patients, may also play a role (see Sfera  et al., 2021 [124] for a review of COVID-19 molecular effects on mitochondria, blood-brain barrier, stress-related disorders and brain-derived neurotrophic factor (BDNF)).