Last Updated on August 25, 2025
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If you have a loved one who is struggling with a drug or alcohol addiction, you’ve probably noticed a quick deterioration of his or her physical health. However, drastic personality changes often occur as a result of addiction too.
What Behavioral Changes Are Caused By Addiction?
Dishonesty
Most forms of substance abuse are illegal so the majority of people who are addicted to illegal drugs or who misuse prescription drugs don’t want everyone to know. As a result, they are often more secretive about their lives and may lie to cover up their behavior.
Aggression and anger
According to a study from the National Institute on Drug Abuse’s Intramural Research Program, people who are addicted may be more likely to throw sudden fits of rage or act more aggressively.2 Sometimes, this is due to the side effects of the drugs they are on but other factors play a role as well. Unresolved trauma, a lack of anger and stress-management techniques, and chronic stress can all contribute to aggressive behavior as well. An addicted person may also be angry at themselves because they are unable to control their substance abuse and therefore take their frustration out on others.
Manipulation
An addicted person may go to all kinds of lengths to get their drug of choice. This often includes manipulating those around them. If your loved one is addicted to a drug, he or she may use intense cravings as justification for manipulative behaviors and become overrun with feelings of desperation and guilt as a result. To add to it, substance abuse can also reduce a person’s capacity for clear judgment and decision-making, and an addict may try to compensate for his or her lack of control with drugs by attempting to control other things or people in his or her environment.
Risk-taking
Things like driving under the influence, having unprotected sex, or stealing money from friends and family members are not uncommon when addiction is a factor. Studies show chronic substance abuse is linked to changes in the prefrontal cortex of the brain, which affects a person’s planning, attention, emotional regulation, and self-control.3 Many drugs also lower inhibitions, increasing the likelihood that the user will engage in risky behavior while under the influence.
Forgetfulness
Substance abuse often causes memory problems because drugs interfere with the brain’s cognitive functions and disrupt the way memories are processed.4 This often comes across as forgetfulness to friends and family members who may be unaware of a person’s drug abuse.
Frequent mood swings
Excessive substance abuse affects the brain’s ability to dictate proper emotional responses to stimuli, which can leave drug users vulnerable to frequent and severe mood swings.5 Symptoms of depression can also include irritability and aggression.
Depression and/or anxiety
Depression and anxiety are two mental health disorders that are often exacerbated by drug abuse. Many people use drugs to escape feelings of depression or anxiety, but ongoing substance abuse will only make these symptoms worse. Some drugs or alcohol can also contribute to the development of depression or anxiety by disturbing the natural balance of neurotransmitters in the brain and body.
Paranoia
Many different addictive substances can cause paranoia during intoxication or withdrawal, including cocaine, methamphetamine, LSD, bath salts, hallucinogens, marijuana, and alcohol. Substance abuse can also worsen symptoms of mental health issues that a person is already experiencing, so it is not uncommon for people who abuse drugs to demonstrate paranoid feelings or behavior.
Isolation
When a person starts abusing drugs or alcohol, friends and family often oppose it by confronting the addict. However, these gestures aren’t always well-received and many drug or alcohol abusers will retreat to isolation to protect their addiction and keep it hidden away from loved ones.
Lack of interest in activities
As a person becomes more and more preoccupied with their drug of choice, all their spare moments are eventually used up with thoughts about using the drug, obtaining it, or using it to get high. This leaves less time for other activities like hobbies, school, work, or activities with family and friends.
Criminal behavior
As a substance use disorder worsens, a person will often do anything to get their drug of choice, including stealing money or valuables. This type of criminal behavior may seem uncharacteristic for your loved one, but when someone is addicted, desperate thoughts and strong cravings often take control and override normal decision-making processes.
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Negative Effects of Personality Changes Caused By Addiction
Many drug and alcohol abusers suffer additional consequences as a result of these behavioral and personality changes. As the addiction worsens, your loved one may experience some of the following things:
- Criminal charges or incarceration
- Poor physical health
- Job loss
- Lasting damage to relationships
- Overdose
Sometimes these consequences are enough to motivate someone to get sober and sometimes they are not.
What Should I Do If My Loved One’s Personality Has Changed Due to Drugs or Alcohol?
If you believe your loved one is abusing drugs and he or she has demonstrated some of the behavioral changes listed above, it is important to respond appropriately.
- Educate yourself. The more you understand about addiction, the better you will be able to respond to your loved one and take care of yourself as well. You can find valuable and trustworthy information about addiction and recovery online at drugabuse.gov or www.samhsa.gov.
- Reach out to community support groups like Nar-Anon. These community recovery support groups are designed to help people who are affected by a loved one’s addiction or recovery. Connecting with others who are in similar situations can prevent feelings of loneliness and offer much-needed emotional support as you learn to navigate life with an addicted loved one.
- Encourage your loved one to seek treatment. If you haven’t already, it’s important to urge your loved one to get help for his or her addiction. As you address the issue with your loved one and go about your daily lives, make sure to demonstrate empathy and concern, create and maintain healthy boundaries for your own life, and encourage your loved one to take responsibility for his or her actions.
- Consider hosting an intervention for your loved one. There is absolutely nothing wrong with enlisting the help of others to encourage your loved one to seek treatment for his or her addiction. Host an intervention on your own, write an intervention letter, or work with a professional interventionist to establish a plan that is likely to be effective.
- Help your loved one find a treatment center or program. If your loved one agrees to get treatment, you can help your loved one find a trusted and effective rehab program. If you don’t know how to do this, here are five essential tips for choosing the right addiction treatment program.
What Should I Do If My Personality Has Changed Due to Addiction?
If you recognize that you are addicted to drugs or alcohol and that it has made your life unmanageable, the hardest part is recognizing you have a problem and admitting you need help. Talk to your loved ones, a trusted friend, or your doctor about your addiction and ask them to support and help you find your way back to sobriety.
Most people in your shoes have lots of questions about addiction treatment, recovery, and if they even need treatment to get better, so you are not alone. Take the next step to ensure your recovery by calling (888) 857-0557 to learn more about your treatment options. A Nova Recovery Center representative is available to provide answers and help you find the right treatment program today.
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FAQ: Addiction, Behavior, and Personality Change
What are the signs of personality disorder linked to addiction?
Addiction can sometimes mimic or worsen the signs of personality disorder, including impulsivity, mood swings, paranoia, or difficulty maintaining relationships. While these symptoms may overlap, a professional evaluation is necessary to determine whether they are substance-induced or related to an underlying mental health condition.
What are common personality disorder symptoms seen in people struggling with substance abuse?
Common personality disorder symptoms linked with substance use include chronic dishonesty, emotional instability, manipulative behavior, and withdrawal from family or friends. These changes can be temporary due to addiction or reflect a co-occurring mental health disorder.
Can addiction cause a sudden personality change?
Yes, substance abuse may cause a sudden personality change by disrupting brain chemistry. This can lead to uncharacteristic anger, isolation, or risky behaviors. When these changes appear quickly, it is often a sign of dependency or escalating use.
What are some reasons for personality change during addiction?
The main reasons for personality change include altered dopamine function, impaired judgment, and increased stress on the brain’s reward system. These shifts often result in mood disorders, aggression, or a lack of empathy in day-to-day interactions.
What are the causes of personality change in adulthood related to substance use?
The causes of personality change in adulthood tied to addiction often involve long-term alcohol or drug use, untreated trauma, or chronic stress. These factors can erode coping skills, making it harder for individuals to regulate emotions or maintain healthy relationships.
What is the difference between behavior therapy and cognitive behavior therapy?
Behavior therapy focuses on changing specific harmful actions, while cognitive behavior therapy (CBT) addresses both the thought patterns and behaviors that contribute to addiction. In recovery, CBT is often preferred because it helps clients recognize distorted thinking and replace it with healthier coping strategies.
How does dialectical behavior therapy near me help with addiction recovery?
Searching for dialectical behavior therapy near me can connect individuals with programs that teach mindfulness, emotional regulation, and interpersonal skills. DBT is especially effective for clients who struggle with intense emotions, impulsivity, or self-destructive behaviors linked to addiction.
What are some personality changes examples caused by drug or alcohol use?
Some personality changes examples include becoming secretive, losing interest in hobbies, showing increased irritability, or displaying uncharacteristic aggression. These examples highlight how addiction can reshape a person’s demeanor and priorities.
What can cause a sudden change in personality anger?
A sudden change in personality anger may result from withdrawal symptoms, cravings, or the psychological effects of prolonged substance use. This anger often surfaces as irritability, verbal outbursts, or even aggression that was not present before.
What is the difference between cognitive therapy vs cognitive behavioral therapy?
Cognitive therapy focuses strictly on identifying and changing negative thoughts, while cognitive behavioral therapy (CBT) combines this with behavior modification techniques. In addiction treatment, CBT is typically more comprehensive and effective.
