In a paper published in the Journal of Alzheimer's Disease, the researchers argue that a habit of negative thinking over a prolonged period of time harms the brain's capacity to think, reason, and form memories — putting individuals at greater risk for dementia.
 

Such thinking is common in people suffering from depression, anxiety, sleep disorders, post-traumatic stress disorder, and chronic life stress, Medical Xpress reports. 
 

It not only eats up the finite capacity of brain resources, but also triggers a physical stress response in the brain, which over a prolonged period of time may cause damage and reduce the brain's resilience to Alzheimer's disease, the British researchers found.
 

"Treatments that reduce [negative thinking] exist, and we believe that they may reduce the risk of Alzheimer's disease,” said Robert Howard, a professor of psychiatry and psychopathology who helped conduct the research. “Further research is needed to verify this concept however our new proposal offers a promising line of scientific investigation to reduce the heavy societal burden posed by Alzheimer's disease."