Stimulating the sense of smell could treat Alzheimer’s

Odours may just be the key to tackling Alzheimer’s disease that the scientific community has been looking for. In recent months, there have been headlines about the fact that losing the sense of smell can be an early sign of the condition, but a new breakthrough suggests that sniffing could also lead to a cure.

Research into the humble roundworm has found that teaching it to sniff danger triggers a defence mechanism in the brain. This system protects the creature’s neurons from degeneration, meaning that those exposed to a certain smell had better brain cell rates of survival.

Should such principles be transferrable to humans, and there’s no reason why they shouldn’t, then it could open up a number of treatment options. Non-pharmaceutical approaches to tackling neurodegenerative diseases such as Alzheimer’s would be a huge step forward.

Alzheimer’s is caused by damage to nerve cells in the brain or peripheral nervous system. This leads them to lose functionality over time and eventually die, with no cure or even method of slowing the progression of the disease currently available.

Professor Veena Prahlad of the University of Iowa said: “Theoretically, it should be possible to treat these types of diseases if we can figure out how to stimulate that defence mechanism in people and have it activated more consistently to fix damaged cells. We would need to find the same sensory triggers in humans as we have demonstrated … in worms.”

The reasons for looking at roundworms in the first instance for this research include the fact they are one of the most abundant creatures on the planet. Added to this, they only have 302 neurons, making the study of neurological disease in roundworms much more straightforward than in humans, who have billions of neurons.

Roundworms were split into two groups for the study, with the first being exposed to the scent of a lethal bacterium and the other given the odour of a benign bacterium. Professor Prahlad’s team found that the former group’s cells had a 17 per cent better survival rate after 18 hours.

The researcher believes that the process that led to the survival of the cells was down to the roundworms ‘learning’ the smell and the threat associated with it. They then stored that memory for future use, thus keeping the cells alive.

Alzheimer’s in humans occurs when protein damage in cells accumulates and the body’s central nervous system does not address the issues. It is not known why such problems should be overlooked, but it has serious consequences.

Scientists have therefore scrutinised a defence mechanism called the heat shock response, which can be found in all plants and animals. It is activated by stressors, such as changes in temperature or salinity, which trigger molecular chaperones to be produced. These in turn rid the cells of damaged protein, which could be the key to treating Alzheimer’s in future.

Around 850,000 people in the UK suffer from Alzheimer’s, making it the most prevalent form of dementia. It is particularly common in the elderly and can lead to the loss of independent living, as well as problems with memory and mood swings.