Study links Depression in Heart Patients to Disruption in Circadian Rhythms

Medical science has pointed out that patients who suffer from heart failure generally develop a certain degree of thought impairment and are susceptible to falling victim to depression.

Researchers at the University of Guelph have found scientific evidence regarding the connection between heart failure and cognitive deficit.

Tami A. Martino, director at the Centre for Cardiovascular Investigations, commented on a recent study published in Nature’s Scientific Reports. She explained that the study revealed how the body clock in mice regulates the mood and cognitive abilities and also shed light on how the related portions of the brain are impaired during a stroke. Ms. Martino also serves as an Associate Professor at the University of Guelph.

“Neurosurgeons always look in the brain; cardiologists always look in the heart. This new study looked at both,” said Martino. With more than 30 publications in her name, she has received a Mid-Career Investigator Award from the Heart and Stroke Foundation of Canada.

According to the Heart and Stroke Foundation, almost 33% of heart failures are caused by coronary heart disease. In search of answers, the Canadian Institutes of Health Research are bankrolling most of Tami Martino’s researches in the field of circadian medicine.

‘Human patients with heart failure often have neurological conditions such as cognitive impairment and depression’, said Martino. Her fellow researchers on the project were Austin Duong, Master of Biomedical Science, and Ph.D. student Cristine Reitz. The research team also had Prof. Boyer Winters and Prof. Craig Bailey on the panel. Both the professors were from the faculty of the University of Guelph.

Tami put forward a hypothesis stating that the heart-brain connection involved the “clock”. The “clock” is a circadian mechanism molecule that is pivotal to the everyday rhythmic activities that go on inside the human body.

Most organisms, including humans, are dependable on the Earth’s rotation about its axis to program their “clock”. They take cues from the position of the sun in the sky and their sleep patterns are altered accordingly. The 24-hour cycle, including the changing of the night and day, trigger activities inside an organism.

Prior to this research, Martino had successfully researched how continuously changing circadian rhythms can trigger changes that can worsen heart disease and can negatively impact the well-being of a person.

The research revolved around the findings from several experiments. Normal mice were compared with mice that had a mutation in their circadian mechanism. The findings were rather interesting. The mice that carried a mutation (henceforth “Clock mice”) had undergone a change in their neuron structure. This had affected the parts of their brain linked with cognition and mood.

It was also found that the “clock mice” had a different pattern of blood vessel regulation in and around the brain as compared with the normal mice.

The research was rather intricate. It included microarray profiling so that key genes could be identified across the neural development, mood and metabolism pathways that had undergone alteration as a heart attack was induced in the mice. This was done to simulate a heart attack in humans and to interpret the findings accordingly.

“The results show that the circadian mechanism influences neural effects of heart failure”, said Martino. Martino was quick to point out that there was no known cure exists for the heart condition but developing an understanding as to how the circadian mechanism works and affects the brain could lead towards the improvement of patients’ quality of life.

“Maintaining circadian rhythms especially for patients with heart disease could lead to better health outcomes.”, said Tami. There is case history available to show that patients recovering from cardiac arrests are susceptible to a disturbed body clock even from slight changes in the ambiance and humanly interactions.

Martino said, “The problems faced by medical science in this field are not just related to the heart but to the brain as well. If we’re not yet able to cure heart failure, we should at least be focusing on how we can improve the quality of life for patients”.

Making small changes in the lifestyles of patients can have a great impact on their quality of life. Avoiding significant changes (like waking up late on weekends) in daily routines that upset or disturb the “body clock” can have a huge positive impact on the health of the patients as it can help keep depression and cognitive impairment at bay.

Adeena Tariq

Adeena's professional life has been mostly in hospital management, while studying international business in college. Of course, she now covers topics for us in health.

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