Researchers, buoyed by a spike in promising clinical trials and tools, believe they may be close to unraveling new ways to treat some of the most insidious yet elusive effects of schizophrenia.

Decades of research into treatments, especially for the mental disorder's "negative" effects, have turned up empty, leaving scientists discouraged and patients out of options. But now, for the first time in years, many longtime researchers say it looks like the tide may be turning.