American Scientist

It might be easy to presume that substance abuse patients would be relieved to hear that their addiction is, in essence, a brain disease. After all, that means their predicament cannot be of their own making. But in reality, the label can leave them feeling helpless, with no control over their recovery. Nonetheless, a neurological diagnosis can be systematized, and medicated, making it popular with the pharmaceutical industry. The problem, say Marc Grifell and Carl L. Hart in “Is Drug Addiction a Brain Disease?”, is that their research doesn’t support that diagnosis. Indeed, treating addiction solely as a brain disease ignores research that concludes that rehabilitation therapies could benefit patients more.

Similarly, Sarah Roosth, in “The Shape of Life,” discusses the fraught history of researchers searching for evidence of the earliest life-forms on Earth. The difficulty is that microfossils are so similar to bubbles, inclusions, mineral accretions, and other artifacts that it’s sometimes impossible to prove definitively that a structure had an organic origin. Although microfossils undeniably exist that date life on Earth back to at least 3.7 billion years ago, questions regarding what kind of life existed then and what it might have been capable of (did it photosynthesize, for instance?) have been debated for centuries, and the answers remain mysterious. Roosth argues that in the search for ancient life-forms, we cannot rely on our vision alone but must instead consider the wider contextual data for a purported fossil to reach a substantiated conclusion.

In this issue’s Perspective column, Shawn Sorrells, Arturo Alvarez-Buylla, and Mercedes Paredes describe how their research took an unexpected turn. They set out to confirm findings suggesting that the adult human hippocampus can regrow neurons. However, their research didn’t uncover any new neuronal growth, even though they used several methods that had successfully revealed regeneration in younger human brains. In “No Evidence for New Adult Neurons,” these researchers walk us through their findings and detail how they ultimately became convinced that they were indeed seeing a negative result rather than simply missing what others had found. Although they were expecting criticism, which they have received from some quarters, these researchers nonetheless felt they had to go where the evidence took them. If it turns out that future evidence points elsewhere, they will be open to considering all possibilities— even (or perhaps especially) if the new data changes our understanding of how neurons may reliably be found.—Fenella Saunders (@FenellaSaunders)