Appetite loss in patients with motor neuron disease: impact on weight loss and neural correlates of visual food cues

Motor Neuron Disease (MND) is associated with significant non-motor symptoms, including the loss of appetite. Loss of appetite has emerged as a dominant feature of the disease that may contribute to negative energy balance, faster disease progression and earlier death. We examined the prevalence and impact of appetite loss and analysed neural correlates of visual food stimuli with prandial status and appetite in people living with MND (plwMND). 157 plwMND and 120 non-neurodegenerative controls (NND Controls) were assessed for anthropometric, metabolic, appetite and clinical measures. Of these, 35 plwMND and 23 NND Controls underwent further functional MRI assessment of fasting and post-prandial responses to visual food cues. plwMND presented with reduced appetite (<i>P</i> < 0.001), with loss of appetite being more prevalent in plwMND than NND controls [OR = 2.59 (95% CI: = 1.46-4.61)]. Loss of appetite was not associated with hypermetabolism; however, was associated with fat mass loss (<i>P</i> < 0.05). Imaging assessment revealed no overall difference in response between plwMND and NND controls when viewing non-food and food images. In contrast, we found no prandial response in the temporal pole of plwMND compared with NND controls, and decreased activity in the cerebellum relative to appetite in plwMND. Loss of appetite, not hypermetabolism, contributes to negative energy balance in MND. Alterations in the temporal pole and cerebellum could contribute to altered appetite responses in some plwMND-brain regions not widely considered in appetite control-providing additional evidence to support widespread involvement of non-motor areas in the disease.