Around a third of first year university students have or develop moderate to severe anxiety and/or depression, suggests the first study of its kind, published in the open access journal BMJ Open.

Increasing use of prescription (but not prescribed) and illicit drug use among those without mental health issues at the start of their course is associated with greater odds of developing significant levels of anxiety and depression by the end of their first year, the findings show.

But socialising and getting involved in student clubs, societies, and sports teams is linked to lower odds of developing significant symptoms as well as boosting the recovery of those who already have symptoms of depression and anxiety when they start their course.

The transition to university life coincides with the peak period for the emergence of mental illnesses, most (75%) of which start in young adulthood, note the researchers.

The most common of these disorders are anxiety and depression, known as 'internalising disorders' because they are directed or experienced inwardly and often include sadness and loneliness.

The researchers wanted to find out which factors might predict recovery in students who start university with moderate to severe anxiety and/or depressive symptoms, and which factors might predict the emergence of these symptoms in first year students without pre-existing anxiety and depression.

The researchers drew on the survey responses of a representative sample of first year students  enrolled at a large, research-based, public university in Kingston, Ontario, Canada in 2018.

The survey explored factors previously associated with academic performance and mental health in students, and was offered 2 weeks into the first term in September 2018 and again 2 weeks before the start of the exam period in March 2019.

Respondents also provided additional information on potentially influential factors: parental education; early life adversity, such as divorce and sexual/physical/emotional abuse; and lifetime occurrence of mood and anxiety disorders.

The College Student Wellbeing scale was used to assess students' sense of belonging both within the university campus and with their peers while the Social Support Subscale of the Resilience Scale for Adolescents was used to measure levels of social support.

The amount and frequency of alcohol; sleeping pills and stimulants that hadn't been prescribed; cannabis; painkillers; opiates; psychedelics; and other recreational drugs the students used was formally assessed at both time points.

Some 58% of eligible students completed the first round of questionnaires and assessments (3029 out of 5245) and 37% (1952) completed both sets.

The prevalence of clinically significant anxiety and depressive symptoms among the respondents was 32% and 27%, respectively, at the start of the academic year in 2018. These figures had risen to 37% and 33%, respectively, by March 2019.

Analysis of the factors associated with recovery showed that students with a history of internalising disorders at the start of their course were almost 4 times as likely not to recover from significant levels of anxiety/depressive symptoms as those who without this history.

But students who felt connected to university life and their peers had greater odds of recovery from depression and anxiety, with every one point increases on this scale, corresponding to 18% and 14% higher odds, respectively.

As to the factors associated with the emergence of anxiety/depression over the first year, every 1 point increase in connectedness scale was associated with 10% and 6% lower odds of developing depression and anxiety symptoms, respectively.

But increasing drug use was strongly associated with heightened risk: every 1 point increase in the score, which ranges from 0-24, was associated with 16% higher odds of developing clinically significant levels of depressive symptoms.

This is an observational study, and as such, can't establish cause. And the findings may not be more widely applicable to other universities in other countries, point out the researchers.

Many interrelated factors influence the emergence and maintenance of mental health problems, including biological, psychological, and social factors, they add.

Nevertheless, the findings have important implications for university mental health policies, programmes and practices, with the availability of clubs, societies and sporting activities likely to be key in promoting student mental health and wellbeing, they suggest.

They conclude: "Moderate to severe levels of anxiety and depressive symptoms are common among students at entry to university and persist over the first year. University connectedness may mitigate the risk of persistent or emergent symptoms, whereas drug use appears to increase these risks."