OLSR is a proactive routing protocol for mobile ad hoc networks. In OLSR, each node collects two-hop neighbourhood information and periodically sends topology control (TC) messages to update the link state. Rather than sending TC messages periodically, at each interval each node: (1) monitors betweenness of its two-hop neighbourhood graph; (2) if the measure is in-control no message is sent, otherwise a TC message is sent. Betweenness, a measure of centrality in a graph first used in social and biological network analysis, appears to correspond closely to the multi-point relay sets of OLSR. Hence a significant change in betweenness indicates a significant change in topology. Using this approach the control overhead in OLSR is reduced by 35-40%, with a corresponding savings in energy, and little impact on throughput or delay.