Becoming addicted to drugs or sex causes changes to the brain that can still be seen even after death. Aside from helping forensic investigators figure out how their “clients” might have lived and died, the implications of this discovery also shed light on why addicts find it so difficult to kick their habits, even if they’ve been clean for a while.
When we indulge in highly pleasurable activities like having sex or taking drugs, a protein called FosB becomes active in the parts of the brain that make up the so-called reward circuit. After combining with other proteins, FosB binds to receptor sites that promote the expression of certain neural genes, which in turn alter the activity of the relevant neurons.
However, previous studies have shown that when people develop addictions, the constant strain placed on FosB causes it to undergo epigenetic changes, meaning its genetic expression becomes altered by the addition of certain molecules to its DNA. As a result, it turns into a slightly different protein known as DeltaFosB.
This is particularly dangerous because DeltaFosB is more stable than FosB, so it persists in the brain for a longer period. Consequently, it produces much longer-lasting changes in neural activity, which is what leads to cravings and dependence.
In a new study that appears in the Journal of Addiction Research and Therapy, a team of scientists examined the brains of 15 recently deceased heroin addicts, and found that DeltaFosB could still be seen in the brain regions responsible for pleasure and memory nine days after death.
They suspect that it may persist for even longer in live subjects, which sheds some light on why recovering addicts so often continue to feel cravings even after they have stopped using a drug, and why so many ultimately relapse.
Study co-author Monika Seltenhammer explained in a statement that this could have implications for the development of new strategies to treat those attempting to get over an addiction. “If the addictive craving persists in the brain for months, it is very important to provide protracted after-care and corresponding psychological support,” she said.