* Psychology

We once thought nostalgia was a disease, but it might be key to our survival

   To what end does the brain recall and reward old memories?
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   Modern neuroscientists and psychologists know that a healthy dose of
   nostalgia is good for you, at least if you’re recalling happy days. But
   there was no sweetness to cut the bitter sensation in 1688, when
   Johannes Hofer coined the word in his medical dissertation. A
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   health at risk, says Susan J. Matt, a professor of history at Weber
   State University. In the 19th century, doctors debated whether
   nostalgia was a disease in its own right or something that exacerbated
   other conditions common among troops, like dysentery. Either way, they
   believed it could cause irregular heartbeat, fever, and, in rare cases,
   death.

   Our opinion of nostalgia has evolved since then, but the phenomenon
   still eludes understanding. “It’s a very mixed emotion,” says Frederick
   Barrett, a cognitive neuroscientist at Johns Hopkins University. That
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   treasure, designing a standardized study is difficult.

   But we do know nostalgia has a marked effect on us: Imaging studies
   show us that these experiences have their own neural signature. In
   2016, Barrett reported that meaningful musical cues changed the
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   University of Southampton in England. Since 2001, he and his colleagues
   have generated a growing body of evidence that individuals more prone
   to nostalgia are generally more likely to socialize, feel empathy, and
   find life meaningful. But their work also suggests a more primitive
   purpose for the feeling: The same neurology that makes us long for
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   discomfort and pain. In a 2012 study in the journal Emotion,
   Wildschut’s team showed that lower temperatures make us more nostalgic,
   and that nostalgia makes us feel toasty even when we’re objectively
   colder—a bit of magical thinking that could help people persevere in
   situations that might otherwise feel hopeless. If remembering the
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   Scientists need a lot more information to adequately characterize this
   complex and bittersweet human sentiment. But while centuries of doctors
   considered nostalgia a deadly disease, we now know how wrong they were:
   Our longing for a lost time can help us make it through today.