Research Digest

Lab notes: Scientists identify a possible early stage biomarker for Alzheimer’s

The key protein called F-actin is disrupted, which results in memory loss.

In a significant advance in understanding of Alzheimer’s disease, scientists at the Indian Institute of Science, Bengaluru, have figured out the way memory deficit develops in early stages.

The researchers have found that early breaking down of a protein, fibrillar actin or F-actin, in the brain leads to disruption in communication among nerve cells and consequently memory deficits.

The protein is critical for maintaining the symmetry of mushroom-shaped projections called dendritic spines on surface of nerve cells. These spines protrude into synapses – junctions between nerve cells – and act as docking spots for other neurons to connect and transmit signals. When synapses get disrupted due to loss of, or defects in dendritic spines, flow of information between nerve cells is interrupted.

In the study, researchers used mice that were genetically modified to mimic Alzheimer’s disease to look at proteins involved in maintaining dendritic spine shape and number. F-actin proteins are found within these spines along with another related protein, G-actin. It was found that in mice with Alzheimer’s as young as one month old, F-actin/G-actin balance was disrupted, leading to lost spines. In contrast, formation of toxic protein clumps called amyloid plaques – an early first clinical symptom of Alzheimer’s, was seen when mice were six to eight months old.

Further studies revealed that F-actin loss had an effect on behavior of mice.

When researchers injected a chemical into affected mice that prevented F-actin from breaking down, they found that the mice were able to regain their normal behaviour. “When we stabilised F-actin, we were able to see the behaviour recovery,” pointed out Reddy Kommaddi, first author and DBT Ramalingaswami Fellow at the Centre for Neuroscience, IISc.

To test if similar effects were taking place in human brain, researchers looked at post-mortem brain tissue samples of patients with Alzheimer’s disease, who had been studied for more than a decade before their death. The samples were obtained from collaborator David Bennett at the Rush Alzheimer’s Disease Center in Chicago, USA. Just like the mice with Alzheimer’s, these samples also showed a gradual breakdown of F-actin over time, as their symptoms – memory loss and accumulation of plaques – worsened.

“Because F-actin is a structural protein, it gives shape to all cells in the body, and is present everywhere. It could potentially become a biomarker,” said Vijayalakshmi Ravindranath, senior author and professor at the Centre for Neuroscience.

The research team included Reddy Peera Kommaddi, Debajyoti Das, Smitha Karunakaran, Siddharth Nanguneri, Deepti Bapat, Ajit Ray, Eisha Shaw, David A. Bennett, Deepak Nair and Vijayalakshmi Ravindranath. The study results have been published in the Journal of Neuroscience.

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Relying on the power of habits to solve India’s mammoth sanitation problem

Adopting three simple habits can help maximise the benefits of existing sanitation infrastructure.

India’s sanitation problem is well documented – the country was recently declared as having the highest number of people living without basic sanitation facilities. Sanitation encompasses all conditions relating to public health - especially sewage disposal and access to clean drinking water. Due to associated losses in productivity caused by sickness, increased healthcare costs and increased mortality, India recorded a loss of 5.2% of its GDP to poor sanitation in 2015. As tremendous as the economic losses are, the on-ground, human consequences of poor sanitation are grim - about one in 10 deaths, according to the World Bank.

Poor sanitation contributes to about 10% of the world’s disease burden and is linked to even those diseases that may not present any correlation at first. For example, while lack of nutrition is a direct cause of anaemia, poor sanitation can contribute to the problem by causing intestinal diseases which prevent people from absorbing nutrition from their food. In fact, a study found a correlation between improved sanitation and reduced prevalence of anaemia in 14 Indian states. Diarrhoeal diseases, the most well-known consequence of poor sanitation, are the third largest cause of child mortality in India. They are also linked to undernutrition and stunting in children - 38% of Indian children exhibit stunted growth. Improved sanitation can also help reduce prevalence of neglected tropical diseases (NTDs). Though not a cause of high mortality rate, NTDs impair physical and cognitive development, contribute to mother and child illness and death and affect overall productivity. NTDs caused by parasitic worms - such as hookworms, whipworms etc. - infect millions every year and spread through open defecation. Improving toilet access and access to clean drinking water can significantly boost disease control programmes for diarrhoea, NTDs and other correlated conditions.

Unfortunately, with about 732 million people who have no access to toilets, India currently accounts for more than half of the world population that defecates in the open. India also accounts for the largest rural population living without access to clean water. Only 16% of India’s rural population is currently served by piped water.

However, there is cause for optimism. In the three years of Swachh Bharat Abhiyan, the country’s sanitation coverage has risen from 39% to 65% and eight states and Union Territories have been declared open defecation free. But lasting change cannot be ensured by the proliferation of sanitation infrastructure alone. Ensuring the usage of toilets is as important as building them, more so due to the cultural preference for open defecation in rural India.

According to the World Bank, hygiene promotion is essential to realise the potential of infrastructure investments in sanitation. Behavioural intervention is most successful when it targets few behaviours with the most potential for impact. An area of public health where behavioural training has made an impact is WASH - water, sanitation and hygiene - a key issue of UN Sustainable Development Goal 6. Compliance to WASH practices has the potential to reduce illness and death, poverty and improve overall socio-economic development. The UN has even marked observance days for each - World Water Day for water (22 March), World Toilet Day for sanitation (19 November) and Global Handwashing Day for hygiene (15 October).

At its simplest, the benefits of WASH can be availed through three simple habits that safeguard against disease - washing hands before eating, drinking clean water and using a clean toilet. Handwashing and use of toilets are some of the most important behavioural interventions that keep diarrhoeal diseases from spreading, while clean drinking water is essential to prevent water-borne diseases and adverse health effects of toxic contaminants. In India, Hindustan Unilever Limited launched the Swachh Aadat Swachh Bharat initiative, a WASH behaviour change programme, to complement the Swachh Bharat Abhiyan. Through its on-ground behaviour change model, SASB seeks to promote the three basic WASH habits to create long-lasting personal hygiene compliance among the populations it serves.

This touching film made as a part of SASB’s awareness campaign shows how lack of knowledge of basic hygiene practices means children miss out on developmental milestones due to preventable diseases.

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SASB created the Swachhata curriculum, a textbook to encourage adoption of personal hygiene among school going children. It makes use of conceptual learning to teach primary school students about cleanliness, germs and clean habits in an engaging manner. Swachh Basti is an extensive urban outreach programme for sensitising urban slum residents about WASH habits through demos, skits and etc. in partnership with key local stakeholders such as doctors, anganwadi workers and support groups. In Ghatkopar, Mumbai, HUL built the first-of-its-kind Suvidha Centre - an urban water, hygiene and sanitation community centre. It provides toilets, handwashing and shower facilities, safe drinking water and state-of-the-art laundry operations at an affordable cost to about 1,500 residents of the area.

HUL’s factory workers also act as Swachhata Doots, or messengers of change who teach the three habits of WASH in their own villages. This mobile-led rural behaviour change communication model also provides a volunteering opportunity to those who are busy but wish to make a difference. A toolkit especially designed for this purpose helps volunteers approach, explain and teach people in their immediate vicinity - their drivers, cooks, domestic helps etc. - about the three simple habits for better hygiene. This helps cast the net of awareness wider as regular interaction is conducive to habit formation. To learn more about their volunteering programme, click here. To learn more about the Swachh Aadat Swachh Bharat initiative, click here.

This article was produced by the Scroll marketing team on behalf of Hindustan Unilever and not by the Scroll editorial team.