Illustration by Min Heo

Every year, psychologists publish a staggering amount of research—it’s impossible to read it all. Still, I gave it a shot—and here are the six papers I found most fascinating.

“Estimating the Reproducibility of Psychological Science,” from Science

This paper isn’t really a study; it’s the outcome of an important movement in the field of psychology. In an effort called the Reproducibility Project, researchers at dozens of universities collaborated to replicate a hundred psychology studies that were initially conducted in 2008. They ended up replicating between a third and half of the studies.

Is that result bad or good? It’s inevitable that studies won’t always be replicable—if every study could be replicated, then every researcher would be right the first time; even legitimate findings can prove fragile when you try to repeat them. All the same, the paper concludes that there is “room for improvement” in psychology, especially when it comes to “cultural practices in scientific communication.” Specifically, the authors propose that “low-power research designs combined with publication bias favoring positive results together produce a literature with upwardly biased effect sizes.”

In other words, the desire for novelty drives researchers to overestimate the conclusiveness of their own work. It’s a fascinating and valuable effort to make sure that psychology moves forward in the best way possible.

“What Works in Inpatient Traumatic Brain Injury Rehabilitation?,” from Archives of Physical Medicine and Rehabilitation

Finally, traumatic brain injury, or T.B.I., is becoming a topic of conversation. It’s a huge problem: in 2010, an estimated two and a half million people in the United States sustained such an injury, and between 3.1 and 5.3 million were living with long-term, or even permanent, disability due to its effects. Still, until recently, T.B.I. has been understudied. This issue of Archives of Physical Medicine and Rehabilitation is entirely devoted to the topic, carefully examining the existing evidence regarding the effects of traumatic brain injury and possible future treatments.

Some of the findings are surprising: if you’re female or Asian, you’re less likely to be given a psychotropic drug, regardless of evidence for its applicability. Some are dispiriting: it turns out that we really don’t have a good sense of what works to treat these injuries, and a kitchen-sink-like approach remains the norm. At this stage, the best predictor of your eventual outcome seems to be the severity of the injury, rather than any particular treatment you might receive. But some evidence is promising. Rehabilitation therapy, especially therapy that requires demanding physical or mental activity, does seem to help patients regain function.

“Best Friends and Better Coping: Facilitating Psychological Resilience Through Boys’ and Girls’ Closest Friendships,” from British Journal of Psychology

This study shows that even a single close friendship is valuable in protecting children—even the most vulnerable—against multiple psychological risk factors. It’s not a new idea, but the research is an important empirical step forward.

“Nonpharmacological Treatments of Insomnia for Long-Term Painful Conditions,” from Sleep

Cognitive-behavioral therapy for insomnia! As I’ve written before, it’s hard to break the cycle of sleeplessness. This study offers evidence for one therapeutic possibility. It involves elements of a traditional therapeutic approach, including “psychoeducation, sleep hygiene, stimulus control, sleep restriction, cognitive therapy, and relaxation.” Some interventions consisted of only a series of three phone calls, between sixty and ninety minutes long, in the course of sixty days, while others were as intensive as weekly two-hour sessions for seven weeks. The methods seem initially promising for both sleep quality and fatigue—but only if administered face to face, not over the phone or the Internet. The effect isn’t huge, but insomnia is an increasing problem, and any possible cure is important to note.

“A Mechanistic Link Between Olfaction and Autism Spectrum Disorder,” in Current Biology

Autism is difficult to study, diagnose, and pin down. This study offers a new possibility: a way to use smell as a more objective marker of potential disorder. The connection also offers insights into some of the underlying mechanisms of autism.

“Fibroblast Growth Factor 9 Is a Novel Modulator of Negative Affect,” from PNAS

Depression is notoriously tough to handle pharmaceutically. We still don’t know how S.S.R.I.s work, for instance—or even if they work at all. This paper offers a previously untried target for treatment: FGF9, a neurotrophin (a type of protein) that appears to play a key role in regulating embryonic development and cell differentiation and seems also to be important in regulating our emotional state. In people with severe depression, it appears to be upregulated, or expressed at too high a concentration. In animals that experience chronic stress from social defeat, FGF9 expression in the hippocampus (the part of our brain involved in memory formation, which also seems to be closely connected to depression) increases—while a related growth factor, FGF2, which is tied to lower levels of depression, decreases. It could prove a dead end, of course, but at least it offers new hope in an otherwise difficult landscape.