An additional analysis was undertaken including both MCI‐LB groups only, to assess if MCI‐LB with abnormal MIBG imaging had more severe autonomic symptoms than those with normal MIBG, given that reduced cardiac uptake of MIBG may reflect a ‘body first’ rather than ‘brain first’ synucleinopathy,20 correlating with plasma alpha‐synuclein,21 and may therefore be associated with synuclein accumulation in the peripheral nervous system with resulting dysautonomia. This evidence concerns the gene SNCA and dysautonomia.