The researchers said they were unable to state whether "the introduction of MHFA training in workplaces has resulted in sustained actions by those receiving the training or that it has improved the management of mental health in the workplace".
They note this finding may be due to a lack of research so far.
Improved management, the report says, includes the development by employers of health and wellbeing policies to tackle mental ill-health, creating positive workplace cultures where managers are responsible for maintaining staff mental wellbeing, the provision of support systems such as occupational health services and employee assistance programmes, and treatment interventions.
The evidence review found employees who had received MHFA training had increased knowledge of mental health issues, including signs and symptoms, and confidence to offer support to those with a mental health problem. They also had a better understanding of where to find information and professional support.
The researchers cite a study conducted in Denmark, which found that "positive changes were sustained six months after the training", including improved positive attitudes and reduced stigma towards people with a mental health problem. However, it notes that "these attitudinal changes were limited" and there was no increase in "helping behaviours" six months after the training.
The report says: "It is not known (even in studies by the MHFA course providers) whether the MHFA training leads to sustained improvement in trainees' ability to help colleagues experiencing mental ill-health."
In addition, the HSE researchers found little evidence that MHFA trainers consider the size of the organisation, its sector or its current needs and culture when delivering courses to the workforce. They found that, while published research noted the importance of tailoring training to specific organisations, they failed to present robust evidence for how this could be achieved.
One study with limited insight into the design and delivery of MHFA training in workplaces suggested courses should be modified to address barriers such as confidentiality concerns and fear of being judged for discussing mental ill-health.
In addition, of the 28 training providers evaluated for the research report, "only a few specifically mentioned tailoring the MHFA training for workplaces".
Again, there is currently a lack of studies in this area. Researchers at the University of Nottingham recently launched a study to evaluate the application of MHFA in workplaces and identify those most in need of support and to provide early interventions to employees before long-term sickness absence or "presenteeism" (people attending work when sick) occurs. A report is due out later this year.
The research report concludes: "A number of knowledge gaps have been identified in this evidence review that mean it is not possible to state whether MHFA training is effective in a workplace setting. There is a lack of published occupationally-based studies, with limited evidence that the content of MHFA training has been considered for workplace settings.
"There is consistent evidence that MHFA training raises employees' awareness of mental ill-health conditions. There is no evidence that the introduction of MHFA training in workplaces has resulted in sustained actions in those trained, or that it has improved the wider management of mental ill-health."
The Hazards Campaign, a network of workplace safety and health campaigning groups, activities and union safety reps, said: "The Hazards Campaign has warned against employers adopting MHFA as a sticking plaster solution to the suppurating sore of anxiety, depression and worse caused by insecure work, low pay, excessive workloads, impossible targets, long hours, bullying, harassment and lack of support at work."
Dr Joanna Wilde, a member of the HSE's Workplace Health Expert Committee, wrote on Twitter that the results of the HSE evidence were "unsurprising" and called MHFA an "individualistic response to a systemic problem".
Fionuala Bonnar, chief operating officer of training provider Mental Health First Aid England, told IOSH Magazine: "We are confident that MHFA, as a mental health awareness and skills development course, sits on a solid and growing evidence-base -- both nationally and internationally. Research consistently shows the MHFA course, delivered in 24 countries globally, improves knowledge and confidence in supporting someone experiencing mental ill health, including people in the workplace and wider community.
"MHFA England works with hundreds of organisations who are adopting MHFA training as part of their overall approach to mental health and wellbeing in the workplace and the overriding message from these employers is that making staff more aware about mental health and skilled to support others, creates mentally healthy working environments. Large employers, including Unilever, Deloitte, EY, Mace, Lendlease, Ford, WHSmith, Skanska, Civil Service, Public Health England and NHS England are all choosing to train staff in MHFA because they can see the positive impact it has within their organisations.
"Whilst it is accepted that research on workplace wellbeing interventions is at an early stage, Public Health England and RAND Europe evaluated the evidence base for over 100 workplace wellbeing programmes and last month published a study which aimed to determine the confidence employers can have that an intervention will have a positive impact. MHFA was ranked as having the second strongest evidence base according to the Nesta Standards of Evidence, out of 117 different interventions assessed.
"To help address the gap identified by the HSE's rapid review in evidence base of how MHFA addresses mental health in the workplace, MHFA England CIC is currently working with the Centre for Mental Health on the development of new research which will further look into the impact of MHFA on the person trained and those they support in the workplace. We will also welcome the findings from the University of Nottingham MENTOR study, commissioned by IOSH, which examines the impact of MHFA training in the workplace."