To the Editor Goh et al1 reported on magnetic resonance spectroscopic imaging detection of brain lactate in a community sample of individuals with autism spectrum disorder (ASD) that was strongly correlated with age. In this study, 8 of 41 adults but only 2 of 34 children exhibited lactate peaks as assessed by visual inspection.1 The authors suggested that the presence of brain lactate in their sample was pathological and evidence for mitochondrial dysfunction. Their argument would be stronger if there was evidence of magnetic resonance imaging structural changes secondary to an accumulative adverse bioenergetic impact, as seen in some mitochondrial diseases. It would also be stronger if there was complementary magnetic resonance spectroscopic imaging evidence of other metabolic alterations, such as elevated glutamate, which would be expected due to a shift in energy redox state.2 Moreover, although the authors took care to visually monitor for signs of anxiety or hyperventilation during scanning, they did not use an objective measure of respiratory status such as capnometry. This is an important point because altered respiration associated with acute anxiety is not always obvious and can increase brain lactate.3 Thus, we would advise caution in the authors’ conclusion that these findings reflect clinically relevant mitochondrial dysfunction.