Kenneth Wessels left Newbiggin Crescent in Tullibody, Clackmannanshire around 4.45am on Wednesday, May 4.
Officers, enquiries have established that Kenneth has then driven his Black Toyota Yaris car - registration number SF14 DCT - to Carsebridge Road, Alloa. He has then left his car and walked in the direction of Jellyholm Road and Gartmorn Dam.
Despite extensive enquiries, he has not yet been traced.
Inspector Phil McIntosh said: “We are very concerned about Kenneth and we would urge anyone with information that hasn’t already been reported to police to get in touch.
“Extensive enquiries are ongoing and we are keeping Kenneth’s family informed as our search continues.
“I would like to thank everyone who has helped so far in our efforts to trace Kenneth.”
Anyone who has any information regarding his whereabouts should contact Police Scotland on 101 quoting reference 1083 of May 4, 2022.
It is understood Kenneth has links to Brighton, the Falkland Isles, St Andrews and Aberdeen.
Kenneth is described as white, 6ft tall, medium build, clean shaven with short grey hair.
He was wearing a yellow long sleeved high-vis jacket, blue jeans and was carrying a dark coloured rucksack.