Hinemoa is of Ngāti Kuri, Te Aupōuri, Te Rarawa and Ngāpuhi descent and works as a child and adolescent psychiatrist. She has been a Fellow of the Royal Australia and New Zealand College of Psychiatrists since 2006.
Dr Elder's PhD and HRC Eru Pōmare Postdoctoral Fellowship developed theory and praxis regarding traumatic brain injury from a Māori perspective. She has been an Accident Compensation Corporation provider of neuropsychiatric assessment and treatment for children and adolescents with traumatic brain injury and their families since 2006. Her other subspecialty area of interest is Youth Forensic Psychiatry. Dr Elder was a member of the expert advisory group of Blueprint II, which articulated the framework for New Zealand Mental Health service funding for a further 10-year period.
She is a deputy psychiatrist member of the NZ Mental Health Review Tribunal and on the list of Specialist Assessors/Medical Consultants for assessment under the Intellectual Disability Compulsory Care and Rehabilitation Act 2003. She is the Māori Strategic Advisor at Brain Research New Zealand and is on the advisory board at the Centre for Brain Research, University of Auckland. She is an advocate for the learning and use of Te Reo Māori me ōna tikanga.
Dr Elder was made a member of the NZ Order of Merit for services to Māori and psychiatry in 2019. She was also a member of the Prime Minister's Science Advisors' Cannabis Panel and is the current Chair of the Indigenous working group of the International Association for Child and Adolescent Psychiatry and Allied Professions and on the working group for the Child and Adolescent Psychiatry section of the World Psychiatry Association.