Having persistent negative thoughts in middle age may raise the risk of dementia, leading to Alzheimer’s disease, according to a new UCL-led study. Published in Alzheimer’s & Dementia, the study outlines how people over 55 who had ‘repetitive negative thinking’ (RNT) show an increased risk of cognitive decline as well as the deposition of harmful brain proteins linked to Alzheimer’s.
Lead author of the study, Dr. Natalie Marchant (UCL Psychiatry) 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.
“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. 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, 292 people over the age of 55 were followed over a period of two years who were part of the PREVENT-AD cohort study, and a further 68 people from the IMAP+ cohort. All participants were required to answer questionnaires about how they typically think about negative experiences, focusing on RNT patterns like rumination about the past and worry about the future. They were also asked about any depression and anxiety symptoms.
Participants’ cognitive function was assessed, measuring memory, attention, spatial cognition, and language. Additionally, 113 of the participants also underwent PET brain scans, measuring deposits of tau and amyloid. These are two proteins that cause Alzheimer’s disease when they build up in the brain.
Higher Risk of Cognitive Decline
It was found that people who showed higher RNT patterns experienced more cognitive decline over a four-year period. They also had a higher decline in memory and were more likely to have amyloid and tau deposits in the brain.
Depression and anxiety were shown to have a negative impact on 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.
“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 Dr Marchant.
Researchers believe that RNT could contribute to Alzheimer’s risk because of its impact on indicators of stress such as high blood pressure. Other studies have found that physiological stress can contribute to amyloid and tau deposition.
Co-author Dr Gael Chételat (INSERM and Université de Caen-Normandie) commented: “Our thoughts can have a biological impact on our physical health, which might be positive or negative. Mental training practices such as meditation might help promoting positive- 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.”