Dr Brennan began his scientific career as an honours student in 2011, during which he was awarded the University medal at UTS for his project investigating the role of exosomal small RNAs in prostate cancer. Dr Brennan started his PhD in prostate cancer systems biology the following year at UTS. During this time he identified several microRNAs that were differentially packaged into exosomes, and explored their likely biological roles. This knowledge formed the basis of an invention disclosure shared with the commercialisation department at UTS.

After completing his PhD and graduating in 2018, Dr Brennan found work at a new not-for-profit company called Iggy Get Out that was investigating the systems biology responsible for causing amyotrophic lateral sclerosis (ALS). These early investigations also revealed tantalising opportunities for developing intellectual property positions, which ultimately lead to the founding of GenieUs Genomics, a corporate entity that exists to develop biomarkers and novel treatments for ALS. Dr Brennan transitioned from Iggy Get Out to GenieUs Genomics. As Research Lead, Dr Brennan initiated multiple systems biology focused research projects with the specific aim of discovering new biomarkers and biological targets for novel therapeutics. This work resulted in the filing of patents for both biomarkers and novel therapeutics with the potential to benefit all ALS patients.

Also during his time at GenieUs Genomics, Dr Brennan initiated and oversaw the design of the Deep insight Genomic Analysis Platform (DiGAP). This evolved into a medical research infrastructure program aimed at interrogating the genomes of ALS patients with the aim of discovering genetic drivers of the disease in a personalised medicine model of care.

Dr Brennan's role at NeuRA will now springboard from this experience in genome sequencing analysis, systems biology, and functional genomics to address a huge unmet clinical need in Bipolar Disorder, a complex and heterogeneous disease that is yet to find the key to unlock personalized medicine to improve treatment efficacy and quality of life for patients.