Repetitive Negative Thinking May Increase Risk for Alzheimer’s Disease

Persistently engaging in negative thinking patterns may raise the risk of Alzheimer's disease, according to a study led by University College London researchers. In the study of people aged over 55, published in Alzheimer's & Dementia, UCL 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.

"Depression and anxiety in mid-life and old age are already known to be risk factors for dementia,” lead author Natalie Marchant explained. “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.

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. Their cognitive function was assessed, measuring memory, attention, spatial cognition, and language. Some (113) of the participants also underwent PET brain scans, measuring deposits of tau and amyloid.

The researchers found that people who exhibited higher RNT patterns experienced more cognitive decline over a four-year period, and declines in memory (which is among the earlier signs of Alzheimer's disease), 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 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.