Carlsson was born in Uppsala, Sweden, son of Gottfrid Carlsson, historian and later professor of history at the Lund University, where he began his medical education in 1941. In 1944 he was participating in the task of examining prisoners of Nazi concentration camps, who Folke Bernadotte, a member of the royal Swedish family, had managed to bring to Sweden. Although Sweden was neutral during World War II, Carlsson's education was interrupted by several years of service in the Swedish Armed Forces. In 1951, he received his M.L. degree (the equivalent of the American M.D.) and his M.D. (the equivalent of the American Ph.D.). He then became a professor at the University of Lund. In 1959 he became a professor at the University of Gothenburg.
In 1957 Carlsson demonstrated that dopamine was a neurotransmitter in the brain and not just a precursor for norepinephrine, as had been previously believed.
Carlsson developed a method for measuring the amount of dopamine in brain tissues. He found that dopamine levels in the basal ganglia, a brain area important for movement, were particularly high. He then showed that giving animals the drug reserpine caused a decrease in dopamine levels and a loss of movement control. These effects were similar to the symptoms of Parkinson's disease. By administering to these animals L-Dopa, which is the precursor of dopamine, he could alleviate the symptoms. These findings led other doctors to try using L-Dopa on patients with Parkinson's disease, and found it to alleviate some of the symptoms in the early stages of the disease. L-Dopa is still the basis for most commonly used means of treating Parkinson's disease.
Opposition to fluoridation of drinking water
Carlsson is opposed to the fluoridation of drinking water. He took part in the debate in Sweden, where he helped to convince Parliament that water fluoridation should be illegal due to ethics. He believes that water fluoridation violates modern pharmacological principles, which indicate that medications should be tailored to individuals.