No matter what method a person uses to take opiates, chemicals from the drug reach the brain within seconds. These chemicals cross the protective blood-brain barrier and bind to receptors on brain cells. As a result of this binding, a cascade of chemical events causes euphoria and other short-term effects of taking opiates. However, these brain chemicals also lead to longer-term changes in the structure and the function of the brain. As a result, individuals addicted to drugs often suffer from changes in mood and cognitive abilities.

Effects of Opiate Use on Mood

After crossing into the brain, opiates bind to a class of receptors known as opioid receptors. This leads to a release of endorphins, the chemicals that lead to the characteristic “rush” or high feeling associated with opiate use. Although these drugs can have mood-elevating effects in the short term, they may be related to the depressed mood when taken for more extended periods of time.

In 2014, researchers from St. Louis University investigated the complicated relationship between opiate use and clinical depression. They found that patients who took prescription opioid medications for 90 to 180 days had a 25% higher risk of developing depression; among those who used prescription opiates for more than six months, the risk was 53% higher.

One biological explanation for this may be that prolonged opiate use resets the brain’s reward pathway. Rather than responding to regular rewards in the environment, the brains of people who have been using opiates may require more and more of a reward stimulus to get the same pleasurable effect. Over time, this may lead to lower mood and feelings of apathy or emptiness.

Opiates can also have unexpected effects in people with bipolar disorder. Bipolar disorder occurs when a person has periods of depression and other periods of elevated mood (known as mania). Prolonged opiate abuse may trigger manic episodes or exacerbate the effects of bipolar disorder. This is particularly challenging because people with bipolar disorder may be naturally drawn to the acute effects of opiates, which can alleviate their depressed mood in the short term. In the long run, however, opiates make it more difficult for a person to appropriately regulate mood.

Effects of Long Term Opiate Use on Cognition

Prolonged opiate abuse may also lead to changes in thinking abilities such as memory, logical reasoning, the speed of processing, or attention. In particular, opiates affect the brain’s reward circuitry, including an area called the cingulate cortex. The cingulate cortex is also responsible for helping people make decisions and inhibit impulses. Thus, people struggling with opiate abuse may have difficulty making sound decisions, performing tasks requiring logical reasoning, and inhibiting inappropriate responses. For example, a person with damage to the cingulate cortex from opiate abuse might lash out emotionally or make inappropriate comments in public. Memory and higher reasoning abilities are also affected in those who abuse opiates.

In a 2002 study comparing current and past users of opiates, scientists found that those who were abusing drugs had significant impairment on two or more neuropsychological tests. However, those who were recovering from opiate addiction showed marked improvement compared to current users. This suggests that although long-term opiate use can affect brain areas responsible for cognition, quitting drug use can cause these abilities to bounce back.

Sources

Profile of Executive and Memory Function Associated with Amphetamine and Opiate Dependence. Neuropsychopharmacology. Retrieved March 12, 2015.