David O'Halloran was last seen in the early hours of Friday January 18 after leaving a night-out with friends in Stirling.
The maths student had gone out drinking with friends after finishing work.
He left a nightclub at about 1am in a taxi but got out of the vehicle before returning to his accommodation at Stirling University.
He was spotted by drivers near the university but the last sighting Central Scotland Police have of him is CCTV footage showing him crossing Henderson Street in nearby Bridge of Allan at about 2.20am.
Police have used mountain rescue teams, trained dogs and a helicopter as part of their search, and are now focusing on the Allan Water and River Forth with underwater diving teams.
The 18-year-old's mother, Donna O'Halloran, has said she will use "any means possible" to find her son and is hoping a psychic can help locate him.
Before travelling to the search area today, Ms O'Halloran said: "We're meeting with psychic Paula O'Brien who has a successful track record in helping other police forces in the UK in these kind of cases.
"Basically, we're hoping David will guide her to the area he is in the river, if he's still there at the moment.
"We're trying to find David and we're going to try any means possible at our disposal; hire boats and professionals and any equipment that is needed to find David and try to recover his body back."
At a police press conference last week, Mr O'Halloran's father Alan McInnes said he believes his son is still alive.
Mr McInnes, who is separated from Ms O'Halloran, fought back tears as he appealed for further information on the missing student
He said: "David has been missing for a month and every day we hope that he's found safe.
"We remain 100% sure he is alive and hope somebody has seen him or knows where he is. He may have injured himself and someone has helped him.
"Too many people have said he is no longer with us but we have to remain focused that he is alive and that for whatever reason he can't come home.
"We're looking for a person and not a body. We will continue to believe this until we're told otherwise by police."
After a long pause, Mr McInnes added: "David, son, if you can see or hear this, please know that we miss you, we love you and we all need you home.
"Our family is incomplete without you."