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Much more than a matter of weight

- 3 min
Nakajima Shingo

With a wistful, deadpan look on his face Shingo Nakajima tells out of the blue: he could have pictured himself as a veterinarian. In Japan. This dream of a young boy growing up in Tokyo took a turn along the way and crossed paths with that of Stephanie Fulton, a researcher in the Cardiometabolic Research Theme.

He has been part of her team since October 2019, exploring the neurobiology of food intake, obesity and mood disorders. A one-way ticket from Japan to Quebec that wasn’t obvious at the start.

This research area has interested the young researcher since earning his PhD in nutrition at Hokkaido University. At Tokyo’s National Center of Neurology and Psychiatry, he pursued postdoctoral research for over three years, focusing on the interactions between the brain and nutrients.

The impetus to leave his country came in the form of a grant from the Japan Society for the Promotion of Science. This financial assistance encourages the best young scientists in Japan to conduct research at a foreign research institution.

And off to Montreal he went!

The brain has its moods 

“In Stephanie’s laboratory, I study how diet modifies mood and behaviours. For example, we can observe behaviours of anxiety and depression in our obese mouse models,” he explained.

In obese individuals, the risk of depression and anxiety are higher than in the general population. These mental health problems are the result of a combination of factors: poor diet, lack of physical activity and an accumulation of fat cells. But obesity alone cannot lead to these anxiety- and depression-related behaviours. Far from it!

At the end of 2021, Shingo Nakajima and Stephanie Fulton noted in a scientific journal that metabolic dysfunction, including inflammation and resistance to insulin or leptin, the hormone controlling appetite, are key elements in the manifestation of anxious-depressive disorders in these individuals.

The excessive consumption of saturated fats, such as palm oil and sugar, promotes the appearance of these metabolic changes. In the brain, this type of rich diet causes enough inflammation to modify the neural circuits responsible for controlling mood, motivation and emotions.

The link between nutrition and mental health 

Anxious-depressive disorders in obese individuals are in fact more related to these types of metabolic deficiencies than to body weight itself, in men as well as in women.

For Shingo Nakajima, the goal is clear: make the connection between metabolism and mental health.

“Diet isn’t a drug used on an ad hoc basis to stop a disease. In contrast, it’s a vital pillar in maintaining the good physical and mental health of human beings for the long term.”

With his research, he hopes to pave the way for new therapies by identifying how motivation and anxiety- and depression-related behaviours can be influenced by nutrition and hormones. Because, yes, in the equation, sex is a significant variable.

The gender difference 

Notable differences have been observed between female and male mice, particularly in recent basic research work conducted in Stephanie Fulton’s laboratory.

In psychiatric research, the use of female animal models is still limited. However, the incidence of depression and anxiety disorders is clearly higher in women than men.

The researcher and her team have been exploring this under-researched area: understanding neurometabolic mechanisms specific to women.

As this new era of research begins, Shingo Nakajima will take an alternate route. Not that he regrets his decision to come to the CHUM Research Centre—he has liked everything about it.

But at the end of his postdoctoral training in 2023, he will return to Japan with his family and settle there as a researcher and professor. As to achieving his childhood dream, a return to his native land may be the inspiration he needs. Who knows?

From all different backgrounds

  • + than 20 languages spoken at the CRCHUM (French and English included) 
  • + than 35% of the people in the CRCHUM community were born outside the country  

Women well represented

  • About 60% of graduate students are women 
  • Nearly 50% of postdoctoral fellows are women 

Much more than a matter of weight