Imagine this. A young teenager, 17, years old, who is fully developed. Now imagine this, the same teenager has a fully developed extra set of limbs and a pelvis. That extra set of pair is attached with chest artery. But, how can this happen?

While it is extremely rare, and has a chance of less than one case occurring per 100,000 births. Such things do happen. This is called parasitic twin.

What Is A Parasitic Twin?

It is an extremely rare type of cojoined twin where a baby is born with an underdeveloped twin attached to its body. This condition is also known as vestigial twins. The condition is very closely related to conjoined twins, where babies are connected at birth and share organs. However, the main difference is that in conjoined twins, there are two developed babies, whereas in parasitic twins, only one is fully developed, other one is underdeveloped and non functional.

In such a case, the twin who is developed is medically known as the autositic or the dominant twin. The dominant twin is healthy in most aspect but may have extra tissue, organs, or limbs from the parasitic twin.

The parasitic twin may be attached with the dominant twin through several places. The common joints are at the head, torso, chest, pelvis, buttocks, or back. In these cases, the parasitic twin is not alive and they die either in the womb or during the childbirth.

Doctors Remove Parasitic Twin

Now, let's go back to the case we referred to, where a young teenager had an extra pair of limbs attached to chest. The teenager who has not been named is from Uttar Pradesh's Unnao neighbourhood, and was treated in AIIMS, Delhi. The team of doctors successfully removed the extra set of limbs from his body.

Dr Asuri Krishna, who led the team of specialist who surgically removed the extra limbs told the BBC that only 40 to 50 cases of parasitic twins have been documented in world medical literature, and in those cases, the surgery had been attempted on children. The doctor said that without much medical literature to guide them, the team of doctors depended on "intuition, skill and knowledge".

The doctor shared that the child had two fully formed legs, buttocks and external genitalia, which weighed around 15kg "protruding from his abdomen".

How Was The Surgery Performed?

The doctor shared that first they identified how interconnected the parasitic and host twins were. The doctors took scans and found that parasitic twin was attached to the teen's breastbone. The blood was being supplied from a vessel in his chest. However, "there wasn't much connection with other main organs like the liver or kidneys," said Dr Krishna. The team also found a large cyst in the teen's abdomen.

Then the surgery was performed in two stages. In the first stage, the parasitic twin was removed. Then the cystic mass was extracted from the surrounded area. The entire surgery was completed in two and a half hours and the team of doctors included radiologists, anaesthetists, and plastic surgeons.

The biggest challenge was when the teen's blood pressure dropped as 30 to 40% of his blood flowed to the parasitic twin, however, the doctors were prepared for it and they stabilized him.

Alzheimer’s disease and dementia are often viewed as diseases of old age, with memory loss considered one of their most recognizable symptoms. However, emerging research increasingly points to factors such as diabetes, blood pressure, hormonal changes and lifestyle during midlife, particularly from the 40s onward, that may influence the risk of cognitive decline later in life.

As ageing populations worldwide face a growing dementia burden, doctors are emphasizing the importance of identifying and addressing these risks in midlife. Alzheimer’s disease is a progressive brain disorder that affects memory, thinking and the ability to manage everyday life.

HealthandMe spoke to doctors about the disproportionate burden of Alzheimer’s among women, the link between diabetes and accelerated brain ageing, and how disease-modifying treatments such as lecanemab are changing the treatment landscape. They also highlighted the importance of early assessment to identify cognitive problems that families may otherwise dismiss as normal ageing.

Diabetes And The Ageing Brain: The Quiet Connection

Type 2 diabetes is an important modifiable factor associated with accelerated brain ageing, making cognitive health an important part of diabetes care.

Dr. V. Mohan, Managing Director, Dr Mohan’s Diabetes Specialities Centre and President, Madras Diabetes Research Foundation, told HealthandMe that every diabetes appointment follows a familiar rhythm: check blood sugar, examine the feet, check the eyes, review the heart and kidneys, and renew the prescription. But the brain, more often than not, receives little attention.

Research suggests that type 2 diabetes is associated with accelerated brain ageing, while vascular damage linked to high blood sugar, blood pressure and cholesterol can affect the brain as well as the heart, kidneys and eyes.

The 2024 Lancet Commission on dementia prevention, intervention and care identified diabetes as one of 14 modifiable risk factors associated with nearly half of dementia cases worldwide.

“The message is simple: just as people routinely check their blood pressure, blood sugar, eyes, feet and kidneys, cognitive health deserves attention too,” he said, while suggesting ABCD for Protecting Brain Health in Diabetes:

A – Aim for HbA1c Control

B – Blood Pressure Control

C – Control Cholesterol

D – Diet Management

Why Menopause Matters For Women’s Brain Health

Women carry a disproportionate burden of Alzheimer’s disease. According to Stanford, roughly three women are diagnosed with Alzheimer’s for every two men, while data from the Framingham Heart Study cited by the

Alzheimer’s Association estimated that at age 45, the lifetime risk of developing clinical Alzheimer’s dementia was about 20% for women compared with 10% for men.

Dr. Anmol Singh Rai, Consultant Neurology, Fortis Hospital Jalandhar, pointed out several factors that may contribute to this difference. He noted:

• APOE4 is one important factor. In women, the gene variant has been associated with a greater increase in dementia risk than in men.
• Age is another major factor, with dementia risk rising sharply in older age groups. Since women generally live longer, more women reach the ages when dementia becomes increasingly common.
• Hormonal changes may also play a role. Declining estrogen during menopause can affect brain metabolism and neuronal health, making the menopausal transition an important period for paying attention to cognitive and overall health.

“Managing blood pressure, blood sugar and cholesterol, addressing hearing loss, identifying sleep apnea, staying physically active and addressing depression and social isolation can all form part of a broader approach to brain health,” he told HealthandMe.

Alzheimer’s: Why Early Detection Matters As Treatment Advances

More than 55 million people worldwide live with dementia today, with a new case developing every three seconds. This number is projected to rise to 139 million by 2050.

With the arrival of disease-modifying treatments such as Leqembi (lecanemab), the importance of identifying cognitive decline early has become even greater.

"For three decades, Alzheimer's treatment has leaned on drugs that modestly improve cognition, function and behavior, buying patients and caregivers meaningful time. But none of them alter the underlying biology of the disease," Dr. Praveen Gupta, Chairman, Marengo Asia International Institute for Neuro and Spine (MAIINS), Marengo Asia Hospitals, Gurugram, told HealthandMe.

The disease-modifying therapy for Alzheimer’s, Leqembi, was cleared in the US in 2023, followed by Japan the same year, China in June 2024, the European Union in 2025, and India in August 2026.

"Unlike everything that came before it, lecanemab is designed to act on the pathological process itself, not merely its downstream consequences," Dr. Praveen Gupta said.

However, the treatment is not meant for everyone with Alzheimer’s. It is approved for early Alzheimer’s disease, including mild cognitive impairment and mild dementia, rather than moderate or advanced disease.

That makes timely diagnosis particularly important.

"Patient selection now hinges on confirming amyloid pathology, through cerebrospinal fluid analysis or blood-based biomarkers, before treatment even begins," Dr. Praveen Gupta explained.

Brain Health Should Begin Before Memory Loss

The experts noted that brain health is not something that needs attention only after memory loss begins.

Midlife is an important window to control blood pressure, blood sugar and cholesterol, remain physically active, address hearing and sleep problems, and pay attention to changes in memory or thinking.

For people already showing cognitive symptoms, early medical assessment can help distinguish normal ageing from mild cognitive impairment, dementia or potentially treatable conditions.

Cardiac arrest is considered one of the most urgent medical situations. It can occur unpredictably, at home, at work, while traveling, or anywhere. It is characterized by a blockage in the heart's arteries, and it differs from a heart attack, which is a situation when the heart stops pumping blood into the body. After a few minutes, oxygen deficiency happens and affects the brain and other organs. Therefore, it is important to know how to perform cardiopulmonary resuscitation (CPR).

CPR is an emergency lifesaving technique that uses chest compressions and, in some situations, blowing mouth-to-mouth air into the person who has suffered a cardiac arrest, to help maintain blood circulation and oxygen delivery to vital organs when a person's heart has stopped beating effectively. It does not restart the heart by itself, but it can keep blood flowing until an automated external defibrillator (AED) is available or emergency medical professionals arrive.

Importantly, CPR is not a skill limited to doctors or healthcare professionals. It can be administered by ordinary people for whom learning the basic CPR techniques is easy.

The Importance of Rapid and Efficient Actions in Case of Cardiac Arrest

If someone faces cardiac arrest, rapid actions may save this person's life. If CPR is performed directly and immediately after a cardiac arrest, it will be possible to keep the flow of blood to the brain and other organs before the arrival of medical experts. The use of CPR can improve the chances of survival for patients who have experienced cardiac arrest.

Besides, in combination with early defibrillation through an AED, it can be even more effective. AED is a portable medical device that checks the heart rhythm of the person experiencing cardiac arrest and delivers an electric shock to restart a normal heartbeat.

However, sometimes people prefer to do nothing for fear of mistakes. But it is much more dangerous not to act at all.

Recognizing Cardiac Arrest

It begins with identifying the presence of a possible cardiac arrest in the patient. The patient will generally fall, become unconscious, and will not breathe properly. They can occasionally breathe abnormally with strange sounds, which should not be considered breathing properly.

If you see anyone fall and become unresponsive, check whether they respond to your questions and breathe normally. Tell any passerby to call the emergency services and bring an AED device, if one is present. If the patient is not breathing normally, initiate CPR on them.

What To Do?

If the patient is an adult, hands-only CPR can be done easily by everyone. For this, you need to keep the heel of one of your hands in the center of the person’s chest, keep your other hand over it, and press down with a rapid rhythm. The compression must be continued at a pace of around 100-120 beats per minute.

Also, you can use the AED device if one is available. Turn on the AED and follow the steps according to the voice prompts from it. The AED device will analyze the rhythm of the heart and give a shock.

CPR is a Practical Skill, not Just Medical Knowledge

Another reason for reluctance to administer CPR is the notion that it should be administered only by doctors, nurses, and other professionals. However, even basic CPR can be taught to regular citizens using special courses. It takes only a couple of hours of practice for someone to gain enough confidence to use CPR in emergencies.

CPR training should be more accessible in schools, offices, and residential communities, as it would help people know what to do in those critical first few minutes.

Cardiac arrest will not wait for doctors to show up. When cardiac arrest occurs, the first person on the scene might be either a relative, co-worker, friend, or a total stranger. Knowing CPR will prepare you for these moments of life or death. A simple skill learned today may help save someone’s life tomorrow.

(Dr. Lalit Kapoor, Senior Consultant - Cardiac Surgery and Robotic Surgery – Narayana RN Tagore Hospital, Mukundapur, Kolkata)

Worried about your graying hair? It may reflect a natural cellular response to DNA damage, according to a study by Japanese researchers.

Hair color comes from melanocyte stem cells (McSCs), which live inside hair follicles and produce melanin, the pigment responsible for hair and skin color. These cells are especially sensitive to DNA damage from environmental and internal factors.

While DNA damage is linked to both aging and cancer, researchers at the University of Tokyo found that McSCs can take different paths after being damaged — including one that leads to hair graying and another associated with melanoma, a type of skin cancer.

How Does Gray Hair Act As A Defense?

When McSCs suffer certain types of DNA damage, they can undergo a process called senescence-coupled differentiation, or seno-differentiation. The damaged stem cells permanently differentiate and are eventually lost, leading to hair graying.

This response is driven by the p53–p21 pathway and may help eliminate damaged cells before they can become cancerous.

Also read: Unusually High Cancer-Fighting Immune Cells Could Explain Why Some People Live Beyond 100: Study

What Did The Study Find?

Published in Nature Cell Biology, the study examined how McSCs respond to different types of DNA damage.

Professor Emi Nishimura and Assistant Professor Yasuaki Mohri used long-term in vivo lineage tracing and gene-expression profiling in mice to study the fate of these stem cells.

The researchers found that DNA double-strand breaks triggered seno-differentiation. In this process, damaged McSCs irreversibly differentiate and are lost, resulting in hair graying.

However, the response was different when the cells were exposed to certain carcinogens, including 7,12-dimethylbenz(a)anthracene, or ultraviolet B. In these situations, McSCs could bypass the protective differentiation process, retain their ability to self-renew and expand clonally.

This process was supported by KIT ligand signals from the surrounding tissue and epidermis, which suppressed seno-differentiation and pushed the cells toward a tumor-prone state.

“These findings reveal that the same stem cell population can follow antagonistic fates—exhaustion or expansion—depending on the type of stress and microenvironmental signals,” Nishimura said.

“It reframes hair graying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses,” she added.

Does Gray Hair Prevent Cancer?

Read More: Ferritin Face: Can Pale Skin Signal Iron Deficiency?

Not necessarily. The study does not show that people with gray hair have a lower risk of cancer.

Instead, the findings suggest that hair graying can be the result of a protective cellular response in which damaged stem cells are eliminated. When that response is bypassed, damaged McSCs may persist and contribute to melanoma development.

The researchers say the findings offer a framework for understanding how the same stem-cell population can contribute to either tissue aging or cancer depending on the type of damage and signals from the surrounding environment.

Can You Prevent Premature Graying?

Genetics plays a major role in when hair turns gray. There are also some lifestyle changes that can prevent graying, support hair and overall health. These include:

• Managing stress
• Eating a nutrient-rich diet
• Protecting your hair and scalp from excessive UV exposure
• Avoiding excessive heat and harsh chemical treatments
• Avoiding smoking.