# Ajayan | As 70-year-old Keralam’s population greys at a mounting pace, with those crossing 70 swelling in numbers, the battle against age-related ailments is acquiring a newer urgency. Two recent studies have sounded an alarm over the growing spectre of brain disorders as Keralam steadily is turning into an old-age home. More intriguingly, they point to an unlikely frontier in the quest to understand the ageing brain: the human gut.
The latest research lends fresh weight to the emerging gut-brain connection, suggesting that Parkinson’s disease may have links to an unhealthy intestinal ecosystem. The message is compelling: the road to a healthier brain may well begin in the belly.
Breaking new ground in this emerging field, a pioneering study led by Dr Aneesa PA, under the guidance of Dr Baby Chakrapani PS, Director of CUSAT’s Centre for Neuroscience, and Dr Syam Krishnan of Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), goes beyond mapping the gut microbiome to probe its functional role in Parkinson’s disease. It is the first investigation of its kind in the Indian population, bringing a distinctly local dimension to a growing global scientific inquiry.
If Dr Chakrapani’s research, conducted in association with German scientists, explored the gut-brain connection in mice, the latest investigation takes the inquiry into human territory. It compared 65 Parkinson’s patients attending SCTIMST’s Comprehensive Care Centre for Movement Disorders with 65 healthy individuals, most of them the patients’ spouses. The choice of spouses as controls was particularly significant. Sharing broadly similar food habits, living conditions and environmental exposures, they offered a more meaningful basis for comparison, reducing the possibility of lifestyle-related distortions.
The findings, published in the internationally reputed Nature Portfolio journal npj Parkinson’s Disease, revealed significant differences in the gut bacterial profiles of patients and healthy individuals. The trillions of microorganisms inhabiting our intestines, it appears, may have a far greater bearing on brain health than previously imagined.
Gut speaks, brain responds
Parkinson’s is a progressive neurological disorder in which dopamine-producing nerve cells gradually die, disrupting the chemical signals that regulate movement. Tremors, stiffness and slowed movements are its familiar manifestations. Yet the disease may whisper its warnings long before these tell-tale symptoms emerge. Constipation and other digestive disturbances often precede the onset of motor symptoms by years, offering intriguing clues to the gut’s possible involvement.
The latest study found a higher abundance of bacteria potentially associated with inflammation in Parkinson’s patients, alongside a depletion of beneficial bacteria that produce short-chain fatty acids. These compounds help maintain the intestinal lining and regulate immune responses. Their decline could weaken the gut’s protective barrier, allowing inflammation to take root and potentially spread.
More significantly, variations in specific bacterial populations showed strong associations with disease severity and other clinical features. The researchers, supported by a multidisciplinary team of bioinformaticians, microbiologists and biotechnologists, suggest that these microbes could influence disease progression through pathways involving dopamine and glutamate, two crucial chemicals governing movement and other brain functions.
Why Keralam matters
Gut bacteria carry a distinct microbial fingerprint shaped by diet, age, sex, lifestyle and genetic background. What goes into the stomach, therefore, may influence what happens much farther up in the human system. Regional differences in food habits and living patterns could also explain why studies in different countries have not always identified the same bacterial signatures associated with Parkinson’s.
This is where the Indian study assumes particular significance. While earlier investigations have largely concentrated on Western and East Asian populations, South Asians have remained conspicuously underrepresented. Identifying bacterial patterns distinctive to Kerala’s population could eventually help develop relatively simple tests for early detection and open avenues for treatments aimed at restoring gut health. The researchers see this as a promising possibility, not an immediate clinical application.
When the gut unsettles memory
The earlier study led by neuroscientist Baby Chakrapani had already offered a fascinating glimpse into this intimate biological conversation. Researchers induced gut dysbiosis, a disruption of the delicate microbial balance, in mice through a 14-day course of broad-spectrum antibiotics. Behavioural tests that followed revealed a striking pattern: long-term spatial and recognition memory suffered significantly, while short-term or working memory remained largely intact.
The damage was particularly pronounced in long-term memory formation, a process centred in the brain’s hippocampus. The researchers investigated how disturbances in the gut could activate the brain’s immune cells, setting off inflammatory responses that impair neural networks.
Taken together, the two studies open an intriguing window into how intestinal health may influence the brain, from memory and cognition to the mechanisms associated with Parkinson’s. They also bring a familiar message into sharper scientific focus: a fibre-rich diet, regular exercise and adequate sleep can help nurture a healthy gut environment.
The human body, after all, is no collection of isolated organs. It is an intricate conversation between systems, some of whose most consequential exchanges may take place far from where the symptoms eventually surface. The gut, long dismissed as merely the body's digestive furnace, is increasingly emerging as an important player in brain health. In an ageing Keralam, that discovery deserves more than scientific curiosity. It calls for a fresh appreciation of the fact that keeping the brain healthy may begin with keeping the gut in good order.