Mandela's close friend since 1948 George Bizos, who had defended the Nobel Peace Prize winner during his 1960s treason trial, said he visited the elderly statesman at his home here just over a week ago.
The former president was doing okay but that his memory had faded, said the noted human rights lawyer.
Mandela seemed to forget that their mutual friends, who were also anti-apartheid activists, had already died, he said.
"Unfortunately he sometimes forgets that one or two of them had passed on and has a blank face when you tell him that Walter Sisulu (former leader of the ruling African National Congress) and some others are no longer with us," Bizos told 'Eyewitness News' in an interview published on Monday.
The 94-year-old Mandela was aware of current political events, Bizos said, adding that the former president never really spoke about issues within government after he stepped away from public life.
"If he was asked 'What do you think about this or that issue', his inevitable response was 'Go and ask my president'. He never wanted to second guess his successor."
Mandela was back home on Sunday after spending a night in a hospital where he underwent a "successful medical examination".
He was admitted to a hospital on Saturday less than three months after being treated for a lung infection and gallstones.
Mandela spent 18 days in hospital in December for treatment of a recurrent lung infection and surgery to extract gallstones. It was his longest stint in hospital since his release from prison in 1990.
His health has been a cause of concern for many years.
He is South Africa's first black president from 1994 to 1999 and is widely regarded as the father of the nation for leading the struggle against apartheid and for democracy.