Heterozygous neuron-specific LPL deficient mice (NEXLPL+/-) also develop obesity on a delayed time course, and herein we use aged NEXLPL+/- mice to show for the first time that mice with neuron-specific deficiency of LPL display learning and memory deficits in addition to other behavioral abnormalities, clearly demonstrating the importance of neuronal LPL in cognitive function. The gene discussed is LPL; the disease is obesity due to melanocortin 4 receptor deficiency.