The Scottish Association for Mental Health (SAMH) study found 43 percent of people experienced gaps in their care or treatments since lockdown started in March.
It also found the number of people who said they are coping “very or quite badly” has doubled from 23 percent in the months before the pandemic to 45 percent by August.
And it revealed those experiencing thoughts of suicide rose to 59 percent - up by 3 percent on pre-lockdown figures - and, worryingly, one in 10 people had not sought treatment even though they felt they needed it.
Billy Watson, chief executive at SAMH, said: “It is now clear that the pandemic has caused serious problems for people who need mental health services. Nationwide, fewer people are being referred for or receiving psychological therapies and Child and Adolescent Mental Health Services (CAMHS), and we’re instead seeing a shift away from people seeking professional help and instead turning to friends and family for support.
“While there have been steps to increase the capacity of mental health services, we now require an ambitious and well-resourced plan to redesign a system that was already under stress before the pandemic. Failure to do so will put lives at risk.”
The SAMH study, which ran from July 30 to August 25, surveyed 725 people over the age of 16 who had been referred to - or were receiving treatment from - a professional or service for their mental health at any time since January 2019.
Nearly 80 percent of respondents were women and most people surveyed were aged 25-54, though all age bands were represented from all of Scotland’s health boards.
Researchers examined areas including care quality, frequency and communication.
The figures, released as the country marks six months since lockdown started, found 45 percent of people felt the quality of their treatment had worsened during the pandemic and their treatment had become less frequent, with 58 percent agreeing that opportunities to discuss their care or treatment had worsened.
Communication with service users was also found to be suffering with 42 percent of respondents receiving no information on how their treatment would be affected by the pandemic and, of those who did receive information, nearly two thirds said they were worried about how the changes would affect them.
People were more likely than not to be satisfied with most aspects of the support they received since March, particularly in relation to reassurance about access to medication. Despite this, 40 per cent were dissatisfied with the response they received while in crisis.
Confusion around the priority of services and orders to protect the NHS also had an impact, with one person saying:“I feel like my symptoms have got worse, but I can do nothing about it as we keep getting told to protect the NHS so I have given up basically on seeing anyone.”
The SAMH research will be continuing this year and is expected to finish in December.