The finding has prompted the Women’s Royal Voluntary Service (WRVS), which carried out the research, to call for action to address the “extreme loneliness” suffered by thousands of elderly people.
The survey found 26 per cent of people aged 75 who lived alone described themselves as “being lonely”.
And one in 20 of elderly people questioned for the study told how they could go for days at a time without speaking to another person.
Nearly a fifth, 18 per cent, said living alone had made them lose their confidence. Of these people, one in four now suffers from depression.
The WRVS also discovered that 20 per cent of Scots surveyed were unable to leave their home because of their poor health, including a fear of falling or inability to walk very far.
Margaret Paterson, head of WRVS services in Scotland, said: “Sadly, extreme loneliness experienced by thousands of older people in Scotland every day often goes unnoticed for too long. The consequences then are a lot more serious than they need to have been.
“The prescription for loneliness, however, is relatively inexpensive and achievable – it is about helping older people in small ways.”
The WRVS is hosting a conference in the Scottish Parliament today to highlight the “epidemic of loneliness” it says affects a growing number of older people. It hopes the move will lead to a greater understanding of the scale of older people’s suffering as a result of living on their own, often with no family members nearby.
The charity is looking at new ways of providing services to senior citizens to encourage them to socialise while at the same time get access to nutritious food and initiatives include monthly lunches in local pubs.
Latest figures show there are just under 170,000 people over the age of 75 living alone in Scotland.
The WRVS said health experts had linked extreme loneliness to a deterioration in health, normally as a result of sufferers not eating. The latest study found 8 per cent of older people who are lonely also admitted to not eating properly.
The charity Age Scotland said badly designed communities and poor public transport across the country were partly to blame for elderly people not feeling confident about leaving their homes.
More than 500 elderly people took part in the study, published today.
Originally set up as the Women’s Voluntary Service in 1938, the charity played a crucial role during the Second World War. It is now focused on helping older and vulnerable people to remain independent and get more out of life.
WRVS is one of the largest voluntary organisations in Britain with around 40,000 men and women helping others.