Persistent negative thinking patterns may raise the risk of Alzheimer’s disease, according to a new study.

In a study of people over the age of 55, researchers found repetitive negative thinking (RNT) is linked to subsequent cognitive decline, as well as the deposition of harmful brain proteins linked to Alzheimer’s.

The researchers say RNT should now be further investigated as a potential risk factor for dementia, and psychological tools, such as mindfulness or meditation, should be studied to see if these could reduce dementia risk.

“Depression and anxiety in mid-life and old age are already known to be risk factors for dementia,” said lead author Dr. Natalie Marchant of the University College London in England. “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.”

“Taken alongside other studies, which link depression and anxiety with dementia risk, we expect that chronic negative thinking patterns over a long period of time could increase the risk of dementia,” she continued. “We do not think the evidence suggests that short-term setbacks would increase one’s risk of dementia. We hope that our findings could be used to develop strategies to lower people’s risk of dementia by helping them to reduce their negative thinking patterns.”

For the study, the research team from UCL, INSERM, a Paris-based research institute, and McGill University in Canada studied 292 people over the age of 55 who were part of the Prevent Alzheimer’s (PREVENT-AD) cohort study, and 68 people from the International Mind, Activities and Urban Places (IMAP+) cohort.

Over a period of two years, the study participants responded to questions about how they typically think about negative experiences, focusing on RNT patterns like rumination about the past and worry about the future. The participants also completed measures of depression and anxiety symptoms, according to the researchers.

Cognitive function was assessed, measuring memory, attention, spatial cognition, and language. The researchers reported that 113 of the participants also underwent PET brain scans, measuring deposits of tau and amyloid, two proteins that cause the most common type of dementia, Alzheimer’s disease, when they build up in the brain.

The researchers found that people who exhibited higher RNT patterns experienced more cognitive decline over a four-year period, and declines in memory, and they were more likely to have amyloid and tau deposits in their brain.

Depression and anxiety were associated with subsequent cognitive decline, but not with either amyloid or tau deposition, suggesting that RNT could be the main reason why depression and anxiety contribute to Alzheimer’s disease risk, the researchers postulate.

“We propose that repetitive negative thinking may be a new risk factor for dementia as it could contribute to dementia in a unique way,” said Marchant.

The researchers suggest that RNT may contribute to Alzheimer’s risk via its impact on indicators of stress, such as high blood pressure, as other studies have found that physiological stress can contribute to amyloid and tau deposition.

“Our thoughts can have a biological impact on our physical health, which might be positive or negative,” said Dr. Gael Chételat of INSERM and the Université de Caen-Normandie. “Mental training practices, such as meditation, might help promoting positive thoughts, while down-regulating negative-associated mental schemes.

“Looking after your mental health is important, and it should be a major public health priority, as it’s not only important for people’s health and well-being in the short term, but it could also impact your eventual risk of dementia.”

The researchers hope to discover if reducing RNT, possibly through mindfulness training or targeted talk therapy, could in turn reduce the risk of dementia. Marchant and Chételat and other European researchers are working on a large project to see if interventions such as meditation may help reduce dementia risk by supporting mental health in old age

The study was published in Alzheimer’s & Dementia. 

Source: University College London