Nii is the Founding President of the Association for Suicide Prevention Ghana (GASP). He is a Community and Applied Health Psychologist by training, but he also has a strong inclination towards General Psychology and mental health advocacy. He is currently a Senior Lecturer in the Department of Psychology, University of Ghana, Legon, Accra. His research focuses on understanding the epidemiology and preventing adolescent and youth self-harm and suicidal behaviours in low- and middle-income countries (LMICs), particularly, those in (sub-Saharan) Africa. Nii is passionate about developing community-based and in-school interventions to promote adolescent mental health in LMICs, mainly, those within sub-Saharan Africa. He has keen interests in the application of multi-ecological frameworks and interdisciplinary models to understand adolescent self-harm and suicidal behaviours.