According to a study published in Alzheimer’s & Dementia, cognitive decline and the deposition of harmful proteins in the brain linked to Alzheimer’s Disease (AD) may be related to the practice of repetitive negative thinking (RNT). RNT, also called perseverative thinking, consists of rumination on the past and worry about the future. The term RNT describes the process, not the content or the time orientation.
A team of psychiatrists and researchers from University College London, McGill University and Université de Caen Normandie sought to examine the relationship between RNT and longitudinal cognitive change. They also looked at RNT and AD pathologies using neuroimaging markers of amyloid beta and tau, then compared symptoms of depression and anxiety and these neuroimaging markers.
Psychological Factors and Biological Health
Several psychological risk factors for cognitive decline have recently been identified. These include depression and anxiety, which have primarily been considered independently. The Cognitive Debt hypothesis suggests that the RNT mechanism may underlie the risk associated with each of these factors.
“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,” said lead researcher and psychiatrist Dr. Natalie Marchant.
RNT and Cognitive Decline
The study, which was conducted over the course of two years, had a total of 292 participants (age 55 and older) divided into two cohorts. Participants responded to questions about how they typically think about negative experiences and completed measures of depression and anxiety symptoms.
Cognitive function was assessed with measures of memory, attention, spatial cognition, and language. Some of the participants (n=113) also underwent positron emission tomography (PET) brain scans. These scans measured deposits of tau and amyloid beta, two proteins whose accumulation in the brain is thought to cause AD.
The researchers found that people who exhibited a higher frequency of RNT patterns experienced greater cognitive decline over a 4-year period. The subjects experienced memory difficulties — one of the early signs of AD — and more amyloid beta and tau deposits in the 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. “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.
Further investigation into the relationship between RNT and AD is needed, as most of the individuals in the cohorts were already at high risk. Studies must be conducted to see if the results are repeated in the general population.
Implications for Prevention and Treatment of AD
The study suggests that RNT may contribute to AD risk via impact on indicators of stress such as high blood pressure. Other studies have found that psychological stress can contribute to amyloid beta and tau deposition. But this study also indicates that thoughts can have a biological impact on physical health. Dr. Marchant has another large European project in progress to determine whether reducing RNT, possibly through mindfulness training, meditation, or targeted talk therapy, could reduce the risk of dementia.
Although there have been more than 400 clinical trials for AD drugs, nothing has been found that can alter the course of the disease. It is the only condition in the top ten causes of death with no treatment to prevent it, stop it, or slow its progression. In the absence of any effective disease-modifying treatments for AD, there is an urgent need to identify the risk factors that can increase the likelihood of dementia onset.
June is Alzheimer’s and Brain Awareness Month, and QPS joins the Alzheimer’s Association in raising awareness and inspiring action.
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