Brenes Estrada was born in Jinotepe, Carazo Department, Nicaragua, on 15 August 1910. She married Manuel López Mayorga, an industrial worker, and the couple went on to have six children (three sons and three daughters). She dedicated herself to her household chores but learned to make paper flowers, which she sold on custom orders.
In 2005, she traveled to Costa Rica and the United States. She underwent eye surgery when she turned 100. In August 2016, her 3 daughters were still alive: Maria, Rosario, and Ana. At that time, she also had 12 grandchildren, 18 great-grandchildren, and 2 great-great-grandchildren. At the age of 106, she was able to read without glasses. At the age of 113, she was taking medication for hypertension.
Mercedes Brenes Estrada passed away in Managua, on 5 July 2024, at the age of 113 years, 325 days.
On 26 March 2022, following the passing of 112-year-old Marcelina Araúz de Maure of Panama, she became the oldest (documented) living person in Central America.
Her age was verified by Fabrizio Villatoro, Santiago García Medina, with the assistance of her family, and validated by LongeviQuest on 16 April 2024.