Postmortem Findings

When the brains from addicts that have died are analyzed (referred to as postmortem studies),⁵ there are many biochemicals whose levels are changed. It still is not clear which chemicals and brain regions are the most significant for drug addiction, but we have many hints. It is likely that changes in many chemicals and many neurons (as opposed to one chemical in one neuron) are required for the addiction process. So, although we don’t know the full story, we have at least the beginnings of a story.

Postmortem studies have been carried out in several species including man. In general, the results point out many neuroplastic changes that amount to significant impairments in neuronal function. Receptors, such as D2 dopamine receptors and glutamate receptors, signaling proteins, proteins involved in energy metabolism, and proteins involved in cell structure were found to be changed by drug use.⁶ Proteins are large molecules that are chains of amino acids and can have many uses in the cell, from being receptors to being transporters. But, the exact proteins that are changed might depend on the drug that is studied. This approach to looking at multiple brain changes in biochemical assays is somewhat easier and cheaper than imaging approaches, which usually focus on just one biochemical, such as a dopamine receptor, at a time.