Could Negative Thinking Be Linked To Alzheimer’s Disease? (Forbes.com, June 2020)

According to new research, repetitive negative thinking might be associated with cognitive decline, though the nature of the association is still unclear.

Researchers from University College London looked at 292 people aged 55 and above. They were assessed on their cognitive function, including memory, attention, spatial skills and language.

Of these participants, 113 agreed to have their brain scanned, allowing the team to measure deposits of tau and amyloid proteins - biological markers for Alzheimer's disease (AD).

Across a period of two years, the participants were then asked about how they usually think about negative experiences, including how they thought about the past (rumination) and their worries about the future.

The researchers found that those who engaged in higher RNT patterns experienced a greater cognitive decline over a four-year period. High rumination and worry was also linked to worse cognitive performance and episodic memory. Not only that, they also discovered a greater buildup of amyloid and tau deposits in their brains - and the greater the buildup, the worse the cognitive decline.

Study lead author Dr Marchant hypothesized in 2015 that negative thinking could be an 'active ingredient' in the development of mental health conditions such as dementia and AD. She dubbed her theory 'Cognitive Debt'.

"People experiencing mental ill health frequently engage in a style of thinking called RNT," she explains. "This style of thinking involves the tendency to have negative thoughts about the future or about the past, and these thoughts can feel uncontrollable."

"These findings do suggest that repetitive negative thinking could one reason why depression and anxiety are associated with AD risk – which is in line with my “Cognitive Debt” hypothesis."

Despite the noted association between RNT and AD, Dr Marchant says they are yet to prove a clear cause and effect relationship. In fact, the opposite might hold true.

"People who experience a decline in their condition may become more concerned or worried about their health – leading to RNT. Or, amyloid or tau could have accumulated in the brain, disrupted its circuitry, making it more difficult to disengage from negative thoughts. At this point we are unable to know which came first."

The researchers conclude that future studies are needed to conclude if these thinking patterns pose a heightened risk of dementia. And if this is the case, people can look at RNT-reducing techniques such as cognitive behavior therapy or mindfulness to help lower their risk of these debilitating neurological conditions.

The study is published in the journal Alzheimer's & Dementia.

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