Those with challenging work had half the rate of decline in memory and thinking compared to those in mentally undemanding work.
Dr Francisca Then, of the University of Leipzig, said: “Our study is important because it suggests that the type of work you do throughout your career may have even more significance on your brain health than your education does.
“Education is a well-known factor that influences dementia risk.
“Challenges at work may indeed be a positive element, if they build up a person’s mental reserve in the long-term.”
The study involved 1,054 people over the age of 75 who were asked about their work history and their tasks were divided into three groups – executive, verbal and fluid.
Examples of executive tasks are scheduling work and activities, developing strategies and resolving conflicts. Examples of verbal tasks are evaluating and interpreting information and fluid tasks were considered to be those which included selective attention and analysing data.
The group were then given tests that measured their memory and thinking abilities every one and a half years for eight years.
Memory and thinking abilities were examined through a clinical test, the mini-mental state examination (MMSE). In this clinical test, a small decline in points can indicate a clinically relevant deficit.
Results found those whose careers included the highest level of all three types of tasks scored highest on the thinking and memory tests by two MMSE points over people with the lowest level.
People with the highest level of all three types of tasks also had the slowest rate of cognitive decline and over eight years, their rate of decline was half the rate of participants with a low level of mentally demanding work tasks.
Among the three types of work tasks, high levels of executive and verbal tasks were distinctively associated with slower rates of memory and thinking decline.
Participants with a high level of executive tasks scored two MMSE points higher on memory and thinking tests at the beginning of the study and five MMSE points higher after eight years in the study, compared to participants with a low level of these tasks.
Those with a high level of verbal tasks declined an average two MMSE points less than those with a low level.
The study was published in Neurology, the medical journal of the American Academy of Neurology.