Addiction creeps in, and it’s often quiet. But once it takes hold, it can reshape everything about who you are, your habits, your priorities, and even your personality.

It’s not just about the substance or behaviour itself. Addiction can fundamentally alter the way you think, feel, and interact with the world.

If you’re looking to develop a better understanding of why this happens, this blog article will explore why that happens, what it looks like, and why people seem to act “out of character” when they’re in the grip of addiction.

Why Do Personality Shifts Happen in Active Addiction?

At its core, addiction will hijack and, in some ways, take control of the brain and how it operates.

The substances or behaviours that lead to addiction, whether it’s alcohol, drugs, or even a behavioural dependency such as gambling, alter and mess with the reward system in your brain.

Typically, this system rewards you with a controlled and natural amount of dopamine when you do something enjoyable, such as eating your favourite meal or having a laugh with a friend. However, addictive substances and behaviours push this system into overdrive, releasing dopamine in large, unnatural quantities.

Over time, your brain simply becomes less responsive to natural rewards. It begins to start craving the artificial high because it’s quicker, easier, and it feels euphoric. The need for that next fix overrides everything else.

A misconception we often see is that this is an entirely physical craving. It is not. This is a mental and emotional shift.

So, a result of this is that our priorities, decision-making processes, and emotional responses are all impacted, and this can make us act in ways that would feel completely foreign, even to ourselves.

Acting Out of Character and Addiction

One of the most painful aspects of addiction, for both their loved ones and eventually the person experiencing it, is how it can make someone behave in ways that seem completely and utterly out of character.

The friend who was always generous and optimistic suddenly becomes secretive and selfish. The partner who was once calm and a steady force in your life starts lashing out or withdrawing emotionally. The parent who is family-oriented and dedicated becomes distant and disinterested.

But why does this happen? Well, the truth is that there’s not one answer to this question. There are multiple.

The Priority Shift

Addiction will reorder your life.

The substance or behaviour becomes priority number one, without choice, and it is often at the expense of everything else that person once held dear in their lives. That’s why people might neglect relationships, jobs, or even their health, and other things that used to matter deeply to them.

Unpredictable Emotional Dysregulation

Addictive substances and behaviours affect the parts of the brain that help regulate emotions.

So, for example, what this can mean is that someone who was once a calm and patient person might suddenly seem irritable or prone to angry outbursts. In the same way, someone who is usually known to be outgoing might become withdrawn and moody.

Deception and Denial

This isn’t always true for everyone, but very often, addiction comes with a hefty dose of denial. So, to sustain the habit, you might see people in active addiction lying to themselves and others. And this is not necessarily out of malice but because they genuinely believe they’re still in control.

This can lead to a lot of secrecy and behaviours that seem manipulative or dishonest, but the way they are behaving is not theirs. This is often a key indicator that addiction has taken hold and is controlling their actions and thoughts.

Loss of Interest in Passions

When addiction takes a real hold, the things that used to bring joy or purpose often fall by the wayside, and it can almost feel as though they’ve forgotten about life before addiction took over.

So, for example, a once-enthusiastic artist might just abruptly stop painting, or a devoted parent might seem entirely emotionally unavailable and as though they don’t care anymore.

In these types of situations, it’s key to remember that they have not stopped caring; their brain is simply laser-focused on feeding the addiction, and this is out of their control now.

Why Does It Feel So Personal?

When someone you love and care about changes because of addiction, it can feel like a betrayal. It’s quite common and, to be quite honest, natural to think, “How could they do this to me?”, “What did I do?” or “Why don’t they care anymore?” as you try to make sense of what’s happening. However, in moments like this, It’s very important to remember that these behaviours aren’t a reflection of their true self, and it’s not your fault. It has nothing to do with you and everything to do with them and what they are battling.

Addiction can and will cloud judgment and override the things that would typically guide their actions, like love, empathy, or responsibility. Everything they’ve learnt to be, who they are, and the moral compass that guides them fall by the wayside.

This might seem contradictory, but although denial is common, it’s also just as common for people battling addiction to feel deeply ashamed of their behaviour at the same time. This doesn’t seem to make sense, as how can they feel shame about what they’re doing if they are living in denial even to themselves that there’s a problem?

Well, here’s the thing. Addiction is not, and will never be, rational. It’s a disease that corrupts the brain, making everything associated unpredictable, and often, there’s a lack of sense to it. So, they may pull away or lash out, not because they don’t care, but because they feel trapped and don’t know how to fix it.

Addiction and Personality Changes: Recognising the Warning Signs

If someone you care about is battling addiction, recognising the changes in their personality can be a wake-up call. Here are some common signs to look out for:

  • Sudden mood swings: They might go from euphoric to irritable in a flash.
  • Withdrawal from loved ones: They may avoid social situations or isolate themselves.
  • Increased dishonesty: Lying about their whereabouts, finances, or habits.
  • Neglecting responsibilities: Work, school, or family obligations fall by the wayside.
  • New social circles: They may start hanging out with people who encourage their addiction.

It’s worth noting that these changes aren’t just about poor choices or a lack of willpower. These shifts in behaviour are symptoms of a disease, which is addiction.

Finding a Way Forward

The good news is that addiction doesn’t have to define a person, and there is always hope, even when it doesn’t feel like there’s any left.

With the proper support and treatment, it’s more than possible to heal and rebuild. This often involves a combination of therapy, medical intervention, and support from friends and family. Recovery is a process, and personality changes can take time to reverse, but they can, and often do, return to something closer to the person’s true self.

If you’re supporting someone through addiction, patience is key. Remember, the person you love is still in there, even if it feels like the addiction has overshadowed them. Encourage them to seek help, set boundaries to protect their own well-being, and try not to take their actions personally – even when it’s hard.

Need Support for a Loved One? Get in Touch

Yes. Addiction is a powerful. And it doesn’t just impact the person struggling with it; it ripples out to everyone around them. The changes in personality can be heartbreaking, confusing, and frustrating, but understanding the why behind these shifts can make it a bit easier to navigate.

The most important takeaway is that these changes aren’t permanent. With time, treatment, and support, people can and do recover. Addiction may alter someone’s personality for a while, but it doesn’t erase who they are. Beneath the surface, they’re still the person you know and care about, and with the right help, they can find their way back to themselves.

Call us on 01253 847 553 for more information on how we can support you.

John Gillen - Director at Ocean Recovery

John Gillen - Author - Last updated: January 13, 2025

John is one UK’s leading professionals in the addiction recovery industry. Pioneering new treatment techniques such as NAD+ and ongoing research into new therapy techniques such as systematic laser therapy, John is committed to providing the very best treatment for people throughout the UK and Europe. During his extremely busy schedule, John likes to regularly update our blog section with the latest news and trends in the industry to keep visitors to our site as well informed as possible on everything related to addiction treatment.