This common harmful habit speeds up cognitive decline

By Connie Capone
Published July 8, 2020

Key Takeaways

Western medicine has historically viewed the mind and body as separate entities, but modern scientific literature continues to prove that the two are one powerful, interconnected, interdependent system. As investigators uncover new complex links between the mind and body, it’s becoming clearer that how one thinks has a direct impact on one’s physical health, and vice versa. The mind-body connection proves that our feelings, attitudes, and physical wellbeing are closely intertwined. But, if our mental and physical health are indivisible, how dangerous are psychological stress and negative thinking to our bodies and brains?

The effects of negative vs positive thinking

Emotions often present in external physiological responses, like a pounding heart or sweaty palms, but they also have internal chemical manifestations. Positive emotions are associated with the hormones dopamine and serotonin, among others. Inversely, negative emotions release stress hormones such as cortisol and adrenaline.

Elevated stress hormones wreak havoc on the brain, according to the National Institute for the Clinical Application of Behavioral Medicine. For one, elevated cortisol weakens short-term memory in the hippocampus and prevents proper memory formation. Stress is also linked to migraines and headaches. In the heart, stress causes increased heart rate, blood pressure, and arterial tension. What’s more, chronic stress causes blood vessels to become clogged and damaged, leading to an increased risk of stroke and heart attack.

But it’s not just how you feel, it’s also how you think. As a matter of fact, a new study published in the Alzheimer's & Dementia Journal shows that a negative mindset can also harm brain function. Over a period of 2 years, nearly 300 study participants—age 55 or older and in good physical and cognitive health—responded to questions about how they responded to negative experiences, focusing on negative thinking patterns such as ruminating about the past and worrying about the future. Participants also measured their depression and anxiety symptoms. The researchers found that those who exhibited higher “repetitive negative thinking” patterns experienced more cognitive decline.

Negative thinking was also linked to greater deposits of two harmful proteins—tau and amyloid—which are responsible for Alzheimer’s disease. In a statement to University College London News, lead author Natalie Marchant, MD, senior research fellow at University College London, said, “depression and anxiety in mid-life and old age are already known to be risk factors for dementia. Here, we found that certain thinking patterns implicated in depression and anxiety could be an underlying reason why people with those disorders are more likely to develop dementia.”

A Singapore study that examined the effects of positive and negative thinking in nearly 400 students corroborated these findings. The study, published in Learning and Individual Differences, found that positive thinking was associated with indicators of psychological wellbeing, namely life satisfaction and happiness. On the other hand, negative thinking was associated with indicators of psychopathology like stress, anxiety, depression, and anger, which can increase the risk of physical ailments.

Scientifically proven methods to increase positive thoughts

In the same way that negative thoughts can affect your physical health, positive thoughts can make you live longer. A study from the Harvard T.H. Chan School of Public Health published in the American Journal of Epidemiology found that a high degree of optimism was associated with a lower mortality risk in women. Among participants who responded to questionnaires about their health behaviors over 8 years, it was found that women who were optimistic had a significantly reduced risk of dying from several major causes of death, including cancer, heart disease, stroke, respiratory disease, and infection, compared with women who were less optimistic.

A seminal study published in Health Psychology also helped to bridge the gap between psychology and biology. In measuring what researchers term “dispositional optimism,” it was found that optimism was clearly associated with better health. In the study, student subjects completed 3 questionnaires one month before the end of a semester. The questions measured optimism, private self-consciousness, and included a 39-item physical symptom checklist. The students completed the same questionnaire again on the last day of class. Results were consistent with what the researchers hypothesized: Participants who initially reported being highly optimistic were subsequently less likely to report being bothered by physical symptoms, than were those who initially reported being less optimistic.

Physical activity, an essential component of good physical health, can also have a positive effect on the brain. For example, physical exercise has been reported to increase synaptic plasticity, neural cell metabolism, and blood supply in the brain, which increases brain processing abilities. In addition, research has confirmed the efficacy of exercise to reduce symptoms of depression and anxiety. For example, the endorphin hypothesis suggests that a release of endorphins following physical activity is related to a positive mood and an overall sense of wellbeing. Studies have also shown increases in plasma endorphins following acute and chronic exercise; however, it remains unclear if these elevations are directly linked to reduced depression.

For other ways to increase positive thinking, the mind-body approach focuses on strategies like meditation and yoga, to name a few. Meditation has been increasingly studied for its purported ability to improve emotional wellbeing. A study from researchers at University of North Carolina at Chapel Hill analyzed the daily emotional reports of adults who meditated over a 9-week period. The results showed significant gains in positive emotions for participants. In addition, those who reported meditating more on average also reported higher than average positive emotions.

Practicing mindfulness is another clinical intervention proven to boost positive thinking. Mindfulness finds its roots in ancient spiritual traditions. To cultivate mindfulness, practice being fully present and aware of thoughts, emotions, bodily sensations, and the surrounding environment. According to research published in the Clinical Psychology Review, the practice of mindfulness provides various positive psychological benefits, such as increased wellbeing, reduced emotional reactivity, and improved behavioral regulation.

If one thing is certain, your mood can have a profound effect on the way you think, feel, and behave. Negative thinking can have a much more detrimental impact on your brain, and positive thinking can be a strong tool in reducing that impact. As the connection between emotions and biological health continues to be studied, it can be useful to practice the suggested methods to increase positive thoughts—from physical exercise to cultivating mindfulness. Common wisdom suggests that you can train yourself to be both happy and unhappy. For the sake of your health, train for the brighter outcome.

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