SYDNEY, May 18 (Xinhua) -- Australia's youth mental health shows early signs of recovery after a sharp pandemic-era decline, but levels remain below pre-COVID benchmarks, according to a new long-term study.

The analysis, based on 24 years of national survey data, found that mental health among people under 25 fell to a distinct low point in 2021 before partially rebounding by 2024, said a statement released Monday by Australia's University of New South Wales (UNSW).

The decline, measured on the SF-36 wellbeing scale -- a widely used self-reported measure of psychological wellbeing -- was steepest between 2019 and 2021, with scores dropping by around five points before regaining roughly two to three points by 2024.

The downturn began in the mid-2010s and was intensified by the COVID-19 pandemic, suggesting the causes such as smartphones and social media among adolescents, rising housing and cost-of-living pressures, climate anxiety, and academic stress, said the study's lead author Sergey Alexeev from UNSW.

Recovery has been uneven within the under-25 group. Teenagers aged 15-18 have regained only about one-third of lost ground, while those aged 19-24 have recovered close to two-thirds of their decline. Neither group has returned to pre-pandemic levels, researchers said.

The study, published in Australian & New Zealand Journal of Psychiatry, also found a persistent gender gap, with young women reporting significantly poorer mental health than young men.

Older Australians showed little change over the same period, highlighting what the researchers describe as an increasingly "age-divergent" trend, it said.