Menahem also called for larger companies to "improve their employment practices" and "help get more disabled people into work".
Menahem was speaking to HR magazine after the insurers had been awarded the job centre Disability Symbol for its approach to supporting disabled people in the workplace.
She said: "Mental health is a topic I think most organisations are struggling with. There's only a few who could say hand on heart they are tackling it properly, because it's a topic managers are afraid of dealing with.
"It comes down to the HR team working very closely with line managers, spotting issues and making sure we deal with those in the right and appropriate way."
Menahem went on to tell HR magazine: "The other challenge is mental health issues are not always visible. Some managers don't want to deal with it because it's a scary topic for them. And then you've got HR people trying to manage through that and do the right thing for staff.
"It's an area we all need to get better at."
Menahem said Government should encourage companies to work with occupational health specialists in educating managers about disability issues.
She added: "It's very easy for unconscious bias to creep into selection decisions and recruitment practices and whether organisations like to admit it or not I'm sure with resources they could be doing more."
The Disability Symbol was awarded to Hastings Direct last Thursday by Jobcentre Plus. It is awarded to employers who have agreed to meet five commitments in respect to the recruitment, employment, retention and career development of disabled people. The use of this symbol ensures disabled people can recognise employers that welcome applications from them and are positive about their abilities.