Arnav Bhattacharya | Meet Our Researcher Series

Arnav Bhattacharya is a PhD scholar at CHeBA studying the emerging science of the brain microbiome and its potential role in Alzheimer’s disease. His research challenges the long-held view that the brain is sterile, investigating how microbial communities in brain tissue may contribute to the chronic inflammation seen in Alzheimer’s pathology. Using proteomics technologies, he explores clinical and translational questions and has experience across pancreatic cancer, neuropsychiatry, and haematological malignancies. A recipient of the Kwan Fung and Yuet Ying Fung Scholarship, Arnav aims to help improve the prevention, prediction and management of Alzheimer’s disease. 

How did you first get into research?

If I go back down memory lane, it all began when I first extracted DNA from tissue during a workshop organised by my school at the college where I later completed my Bachelor's and Masters degrees, S.R.M. Institute of Science and Technology. The experience intrigued and excited me so much so that I eventually dropped out of Medicine and chose to become a researcher instead of a clinician.

After nearly eleven years of studying and conducting plant, mouse and human research – on topics ranging from breast, pancreatic and blood cancers to animal handling, surgery and brain dissection – I am finally working with human brains. I can confidently say I'm having far more fun than I would have had as a clinician with a single lifelong specialty. My brother and I sat the Medicine entrance exams together; he went on to become a clinician, while I became a researcher. I often joke with him that he is committed to one speciality for life, whereas I can move between different areas of research.

I like to explain it this way; if the healthcare industry were an iceberg, doctors and frontline health professionals would be the visible tip. The much larger portion beneath the surface represents the scientists, biotechnologists, pharmaceutical industries and many others who help ensure the system runs smoothly. That perspective ultimately drew me into research – back in 2014, when I decided to leave Medicine behind.

Did you experience a ‘defining moment’ which led you to this field?

I was introduced to the importance of scientists in developing drugs, vaccines and therapies very early in life, when I heard how my aunt Dr. Sumita Bhaduri-McIntosh, a clinician turned scientist, was working on Epstein-Barr Viruses, studying their effect on paediatric cancers. Another defining moment would be when my grandfather developed lung cancer. Shortly after, my grandmother was diagnosed with Parkinson's disease and dementia. These were profound moments for me that made me determined to understand the mechanisms behind the disease and how medicines and treatments worked. I understood the need for research was equal to or even more than practising medicine. It propelled me to dig deeper into the science and motivated me to get into research. I focused on cancer and neuroscience because I wanted to uncover the answers behind what took my loved ones away.

Do you have any personal interests or activities which are protective behaviours against cognitive decline?

I have been drawing and making pencil sketches for many years. I also enjoy going for walks, both early in the morning and late at night. Walking helps me relax and stay active. I try to combine this with a balanced diet – practicing intermittent fasting and following a high-protein, low-carbohydrate diet to maintain my weight. Most importantly, I am a drummer for an Indian rock band called Indriya here in Sydney – which means ‘the senses’ in Sanskrit. I have been playing percussion instruments since the age of twelve and I've been playing drums for bands and performing at gigs since 2009. Drumming takes all four limbs, it's neuroprotective, protects neuroplasticity in the brain, cerebellum and prefrontal cortex and it improves ear, eye, mind and motor coordination – besides being good for reflex and control, it elevates my mood and keeps me alive and active.

What are you currently researching?

We already know that distinct microbiomes exist throughout the body – including the gut microbiome, the oral microbiome and the skin microbiome. We also know that the gut microbiome affects the brain through bidirectional communication along the gut brain axis, modulating neurotransmitter production via the vagus nerve and all different ways.

The remaining piece of the puzzle is to establish if the microbiome also houses itself inside the brain. I’m currently investigating the infection Alzheimer theory; something people have historically been sceptical about. I'm using cutting edge meta proteomics and metagenomic techniques to crack the presence, the location, the diversity and the abundance of microbes in the brain.

One of the key questions I’m trying to establish is what came first – Alzheimer's or the microbes? Did the microbes lead to Alzheimer's or Alzheimer's led to microbes in the brain? At present there is limited evidence to answer this question, and one of the limiting factors in undertaking this work is finding brain samples to work on. Unlike blood, which can be collected repeatedly throughout a person’s lifespan and across different age groups, brain tissue cannot be sampled from people throughout life – meaning researchers rely on donated brains collected post-mortem. This significantly limits the availability of samples. This is an ongoing challenge in many parts of the world. In several countries, including India, brain banks are limited or non-existent, and ethical approvals can be complex and time-consuming.

Finally, the topic of contamination is also an issue – did we introduce the microorganism while working with the brain tissue or was it there already? Historically, research in this area has faced two major bottlenecks – limited sample availability and the challenge of contamination and proper controls. Our study aims to address both issues.

Why is your research important?

For many years, we have been focusing on targeting amyloid plaques and tau tangles to reverse, predict or treat Alzheimer’s disease. In almost all clinical trials for Alzheimer's drugs, these have failed. Even those that reach late-stage trials, such as Phase 3, often fail to make it to market.

But what if Alzheimer’s could be prevented earlier in life rather than treating it after it develops? If infection is building up for example in a person’s 20s, 30s, 40s or beyond, we could treat the infection aggressively early on. The aim would be to prevent it crossing the blood brain barrier and housing itself in the brain, and leading to Alzheimer's later on. A preventive approach could involve repurposing existing drugs or antibiotics, or developing strategies to protect the integrity of the blood–brain barrier so microbes cannot enter the brain. This would require a longitudinal strategy across the lifespan, aiming to prevent or significantly delay the onset of Alzheimer’s disease.

The impact could be substantial. Countries like Australia already spend millions of dollars on aged care and Alzheimer’s support. If effective preventive strategies were implemented earlier in life, we could reduce the need to wait until people develop the disease before intervening – the focus could shift from cure to prevention.

What do you love about working for CHeBA?

I really appreciate working at CHeBA. It’s a warm and supportive environment that embraces curiosity, idea sharing, and growth through challenges – especially as my project explores theories that challenge existing beliefs about the potential causes of Alzheimer’s disease. Even though the whole department doesn’t always sit together or overlap in the office, it genuinely feels like a big family whenever we connect, whether for meetings or end of year celebrations. There’s a strong collaborative spirit throughout the entire Centre. This extends to Professor Perminder Sachdev and my supervisor Dr Karen Mather. Whenever I share ideas with them, they not only offer their expertise but also show trust in my abilities and have given me the responsibility to lead this particularly challenging project. That support, combined with the Centre’s collaborative culture, makes me feel very fortunate to contribute to research at CHeBA – where creativity is encouraged and colleagues are always willing to offer suggestions in a natural and supportive way. 

What is the ultimate hope you have for your research?

The one hope that I have is that people don't need to reach old age to realise that they have Alzheimer's and then realise there is no cure. Many advances have been made in the treatment of cancer, with many forms now having a cure. I don't want Alzheimer's to be a black box – I watched my grandmother slip away and saw how she faced the disease, but there was nothing we could do about it. She was just 62 years when we lost her. There was Parkinson's on the one hand and dementia on the other – the combination of the two physically and mentally slowed her down and eventually took her away from us.

Arnav Bhattacharya is a PhD student at CHeBA with a special interest in the microbiome of the brain and its possible connection to Alzheimer’s disease. He holds a Master’s degree in Genetic Engineering from S.R.M. Institute of Science and Technology, Chennai, earned in 2020. He has led the Clinical Proteomics Team at Tata Medical Cancer Hospital in Kolkata, applying mass-spectrometry based proteomics to paediatric acute lymphoblastic leukemia. Arnav’s research portfolio includes three publications and notable awards such as the UIPA Scholarship from UNSW for his work on the Microbiome of the Brain study at CHeBA, and a Global Health Travel Award from the Bill and Melinda Gates Foundation for the Keystone Symposia on Molecular and Cellular Biology. He was also the recipient of the UNSW Department of Psychiatry and Mental Health HDR Conference 3MT People’s Choice Award in 2025.