Persistently engaging in negative thinking patterns may raise the risk of Alzheimer's disease, finds a new UCL-led study. 

In the study of people aged over 55, published in Alzheimer's & Dementia, researchers found 'repetitive negative thinking' (RNT) is linked to subsequent cognitive decline as well as the deposition (沉积) of harmful brain proteins linked to Alzheimer's. 

Lead author Dr Natalie Marchant (UCL Psychiatry) said: "Depression and anxiety in mid-life and old age are already known to be risk factors for dementia(痴呆). 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. 

"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 Alzheimer's Society-supported study, the research team from UCL, INSERM and McGill University studied 292 people over the age of 55 who were part of the PREVENT-AD cohort study, and a further 68 people from the IMAP+ cohort. 

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 (沉思) 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, two proteins which cause the most common type of dementia, Alzheimer's disease, when they build up in the brain. 

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. 

 "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. 

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. 

Co-author Dr Gael Chételat 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. "

Here are four famous museums for family visits in Washington DC.

Dinosaur Museum

The museum features evidence, facts and tons of amazing sculptures of some of the most powerful and sometimes scary animals that ever controlled the Earth. The artists used real dinosaur bones to form the reproductions so they are extremely life-like.

Witte Museum

Originally established in 1926, this museum offers guests a comprehensive look at a more than 3-century span (跨度) of history. Called the center where nature, science and culture meet, the museum prides itself on providing guests with immersive (沉浸的) experiences, such as being taken back to cowboy days in the Heritage Center or digging through sand to find dinosaur bones.

The best part? The museum is constantly switching out some exhibits to better suit the season and provide guests with a different experience each time they visit.

Museum of Illusions

Step inside a completely new world at Orlando's newest exhibit the Museum of Illusions! This unique educational attraction is the perfect combination of fun and art, allowing visitors of all ages to test the limits of their mind. Focused on planting the seeds of curiosity, the astonishing images at the exhibitions remind guests that everything is not always as it seems.

World's Largest Toy Museum

Release your inner kid and visit the World's Largest l oy Museum, which will take you back in time with one million toys from the 1800's to today. You'll surely be excited to check out your "hero" toys from your childhood. The tours are self-guided and guests are allowed to leave and return during the same day.

Holding the large and heavy "brick" cellphone he's credited with inventing 50 years ago, Martin Cooper talks about the future.

Little did he know when he made the first call on a New York City street from a heavy Motorola prototype(原型) that our world would come to be encapsulated on a sleek glass sheath where we search, connect, like and buy.

Cooper says he is an optimist. He believes that advances in mobile technology will continue to transform lives but he is worried about risks smartphones pose to privacy and young people.

"My most negative opinion is we don't have any privacy anymore because everything about us is now recorded someplace and accessible to somebody who has enough intense desire to get it," the 94-year-old said in an interview in Barcelona at MWC, the Mobile World Congress, the world's biggest wireless trade show, where he was getting a lifetime award.

Cooper sees a dark side to the advances, including the risk to children. One idea, he said, is to have "various Internets intended for different audiences."

Cooper made the first public call from a handheld portable telephone on a Manhattan street on April 3,1973, using a prototype device his team at Motorola had started designing just five months earlier.

Cooper used the Dyna-TAC phone to famously call his opponent at Bell Labs, owned by AT&T. It was literally the world's first brick phone, weighing 2.5 pounds and measuring 11 inches.

Cooper spent the best part of the next decade working to bring a commercial version of the device to market.

The call helped kick-start the cellphone revolution (革命).

Cooper said he's "not crazy" about the shape of modern smartphones. He thinks they will develop so that they'll be "distributed on your body," possibly as sensors "measuring your health at all times."

Batteries, he said, might be replaced by human energy. The body makes energy from food, he argues, so it could possibly also power a phone. Instead of holding the phone in the hand, for example, the device could be placed under the skin.