How to Process Fear and Trauma Stored in the Human Body

Addiction is a chronic, relapsing disorder involving changes in brain reward, motivation, learning, stress and executive control systems. While different substances (and behaviours) act through distinct primary mechanisms, they converge on common neurobiological pathways — particularly the mesocorticolimbic dopamine system.

Below is an overview in Australian English of the core mechanisms and then substance-specific and behavioural addiction processes.

Core Neurobiological Pathways in Addiction

1. The Mesocorticolimbic Dopamine System

The central pathway implicated in addiction is the mesocorticolimbic circuit, involving:

• Ventral tegmental area (VTA)
• Nucleus accumbens (NAc)
• Prefrontal cortex (PFC)
• Amygdala
• Hippocampus

All addictive drugs increase dopamine transmission in the nucleus accumbens, either directly or indirectly. Dopamine does not simply produce pleasure — it encodes reward prediction, salience and learning. With repeated exposure:

• Drug-related cues gain exaggerated salience
• Natural rewards become less reinforcing
• Behaviour becomes increasingly habitual and compulsive

2. Neuroadaptation and Allostasis

Repeated substance exposure produces:

Tolerance — Reduced response due to receptor downregulation or neurotransmitter depletion.

Dependence — Neuroadaptations that produce withdrawal when the substance is removed.

Allostatic shift — The brain’s reward set point shifts downward, mediated by stress systems (e.g. corticotropin-releasing factor), resulting in dysphoria during abstinence.

3. Habit Formation and Loss of Control

With repeated use:

• Control shifts from ventral striatum (goal-directed) to dorsal striatum (habit-based)
• Prefrontal cortex regulation weakens
• Impulsivity and compulsivity increase

Substance-Specific Mechanisms

Alcohol

Alcohol acts on multiple neurotransmitter systems:

• Enhances GABA-A receptor function (inhibitory)
• Inhibits NMDA glutamate receptors (excitatory)
• Increases dopamine release in nucleus accumbens
• Affects endogenous opioid systems

Chronic exposure leads to:

• GABA downregulation
• NMDA upregulation
• Hyperexcitable state during withdrawal (risk of seizures, delirium tremens)

Alcohol dependence also involves stress system activation and impaired frontal cortical control.

Methamphetamine

Methamphetamine is a potent psychostimulant that:

• Enters presynaptic terminals
• Reverses the dopamine transporter (DAT), causing carrier-mediated dopamine efflux
• Inhibits vesicular monoamine transporter 2 (VMAT2), releasing dopamine from synaptic vesicles into the cytoplasm
• Causes massive dopamine release into the synapse

It also increases noradrenaline and serotonin.

Chronic use causes:

• Dopamine neurotoxicity (particularly to dopaminergic terminals)
• Reduced dopamine transporter availability
• Structural changes in striatum and PFC
• Persistent cognitive deficits

Methamphetamine produces particularly strong sensitisation of cue-driven craving.

Cocaine

Cocaine:

• Blocks the dopamine transporter (DAT), preventing reuptake
• Increases synaptic dopamine concentration

Unlike methamphetamine, cocaine acts by blocking DAT rather than reversing it, and does not cause large presynaptic vesicular release — the elevation in synaptic dopamine arises from impaired clearance.

Repeated use leads to:

• Dopamine receptor downregulation
• Enhanced cue reactivity
• Rapid cycling between intoxication and crash
• Strong psychological dependence

Opioids (e.g. heroin, morphine, oxycodone)

Opioids act primarily at mu-opioid receptors (MORs), which are expressed throughout the brain, including in the VTA. Their dopaminergic effects arise through multiple mechanisms:

• MORs on GABAergic interneurons in the VTA suppress inhibitory tone, thereby disinhibiting dopamine neurons (the classical disinhibition mechanism)
• MORs are also expressed on VTA dopamine neurons and projection targets directly, contributing additional excitatory drive beyond the disinhibition pathway

They also act in brainstem respiratory centres, which underlies the risk of respiratory depression in overdose.

Chronic use produces:

• Receptor desensitisation and internalisation
• Reduced endogenous opioid production
• Severe physical withdrawal mediated by noradrenergic rebound in the locus coeruleus
• Strong negative reinforcement (use to avoid withdrawal)

Cannabis

Δ9-tetrahydrocannabinol (THC):

• Activates CB1 receptors (the primary psychoactive cannabinoid receptor)
• Modulates GABA and glutamate release at presynaptic terminals
• Indirectly increases dopamine in NAc via disinhibitory mechanisms

Cannabis produces:

• Altered endocannabinoid system function
• CB1 receptor downregulation with chronic use
• A mild to moderate withdrawal syndrome (irritability, sleep disturbance, appetite changes)
• Effects on hippocampal memory circuits

While addiction risk is generally considered lower than for opioids or stimulants, it remains clinically significant and may be underestimated, particularly given the widespread availability of high-potency THC products (e.g. concentrates and high-THC flower), which are associated with greater dependence risk and more severe withdrawal.

MDMA (Ecstasy)

MDMA:

• Reverses the serotonin transporter (SERT), causing massive serotonin efflux — this is its primary mechanism
• Also increases dopamine and noradrenaline

Neurobiological consequences include:

• Acute empathogenic and entactogenic effects driven by serotonin release
• Post-use serotonin depletion, which may contribute to dysphoria in the days following use
• Potential serotonergic neurotoxicity, though this evidence comes largely from high-dose or repeated animal studies; the clinical significance in typical human recreational use remains under debate and is not definitively established
• Moderate addictive potential relative to psychostimulants, partly because dopaminergic effects are less prominent than with cocaine or methamphetamine

Prescription Psychoactive Medications

Certain prescribed medications also have addictive potential:

Benzodiazepines — Enhance GABA-A receptor activity. Cause tolerance via receptor downregulation. Dependence is primarily a GABAergic adaptation. Withdrawal can be protracted and, in cases of high-dose or long-term use, may produce seizures.

Prescription stimulants — Act via similar mechanisms to amphetamine, increasing dopamine and noradrenaline. Risk of misuse exists in susceptible individuals, though therapeutic doses in appropriately diagnosed patients are associated with substantially lower addiction risk than recreational use.

Behavioural (Process) Addictions

Gambling Disorder

Gambling disorder is recognised in DSM-5-TR as a non-substance-related addictive disorder. Although no substance is ingested, similar neurobiological mechanisms are involved.

Dopamine and reward prediction error — Near misses activate the nucleus accumbens similarly to wins. Variable ratio reinforcement schedules (as in poker machines) generate strong, unpredictable dopamine prediction error signalling that powerfully drives continued behaviour.

Cue reactivity — Gambling-related cues activate the same mesocorticolimbic circuitry as drug cues, with increased striatal activation and reduced prefrontal inhibitory control.

Habit circuitry — A shift from ventral to dorsal striatal control contributes to compulsive betting despite continued losses.

Other Emerging Behavioural Addictions

Conditions such as internet gaming disorder, compulsive sexual behaviour disorder, and problematic social media use share overlapping neurobiological features including:

• Dopamine dysregulation and sensitisation to cue salience
• Reduced executive control
• Stress system activation

However, the evidence base for most of these conditions is still developing, and their classification as formal addictive disorders remains an area of active research and debate. Internet gaming disorder is currently listed in DSM-5-TR as a condition for further study.

Shared Neurobiological Themes Across Addictions

Across substances and behaviours, addiction involves:

• Dopamine sensitisation to cues
• Reduced sensitivity to natural rewards
• Impaired prefrontal inhibitory control
• Stress system overactivation (particularly corticotropin-releasing factor)
• Habit circuitry dominance (dorsal striatum)
• Neuroplastic changes in glutamatergic signalling

Why Some Substances Are More Addictive

Addictive potential is influenced by multiple interacting factors. The speed of dopamine rise is one of the most studied — faster onset of dopamine elevation (e.g. via smoking or intravenous administration) is associated with stronger reinforcement. This framework, developed largely through the work of Volkow and colleagues, has strong empirical support, though it represents a mechanistic model rather than an established universal law. Other important factors include:

• Intensity of dopamine release
• Pharmacokinetics (e.g. route of administration)
• Withdrawal severity (which drives negative reinforcement)
• Social and environmental context
• Genetic vulnerability (heritability of addiction is estimated at 40–60% across substances)

Conclusion

Addiction is not simply about pleasure seeking. It reflects maladaptive neuroplasticity in reward, stress, learning and executive control circuits. While alcohol, methamphetamine, cannabis, opioids, cocaine and MDMA each act through different primary molecular mechanisms, they converge on common neural pathways that drive craving, tolerance, withdrawal and compulsive use. Behavioural addictions such as gambling engage these same circuits despite the absence of an ingested substance.

The neurobiological understanding of addiction continues to evolve, and where evidence is still emerging — particularly regarding emerging behavioural addictions and the long-term neurotoxic effects of substances like MDMA — clinical interpretation should be appropriately cautious.

By Mitchell Webb | Webb Therapy, Surry Hills Sydney

We all have moments in relationships where we give too much, worry too much, or lose ourselves a little in someone else. That is not codependency — that is being human. But when those moments become the architecture of the entire relationship, when your sense of self, your emotional stability, and your very identity become organised around another person’s needs, moods, and wellbeing, something more significant may be at play.

Codependency is one of the most misunderstood and underdiagnosed relational patterns in clinical practice. It is frequently mistaken for love, devotion, or simply being a caring person. Yet the research is consistent: left unaddressed, codependent patterns cause significant harm to both people involved — and they rarely improve on their own.

This article explores what codependency actually is, what the current evidence says about how to identify it, and — critically — what you can do if you recognise yourself in it.

What Is Codependency, Really?

The term “codependency” originated in the addiction treatment field in the 1970s and 1980s, used initially to describe the partners and family members of people with substance use disorders. Clinicians noticed that the people surrounding someone with addiction often developed their own set of dysfunctional patterns — enabling behaviour, emotional enmeshment, a compulsive need to control or fix the other person — that were distinct from, yet deeply intertwined with, the addiction itself.

Over the following decades, the concept broadened. Researchers and clinicians came to understand that codependency was not unique to addiction contexts. It appeared in relationships involving chronic illness, mental health conditions, emotional immaturity, narcissistic traits, and even in ostensibly “normal” relationships where one person had learnt, usually in childhood, that love was conditional on their usefulness or selflessness.

The American Psychological Association (2023) now broadly defines codependency as an emotional and behavioural pattern characterised by excessive reliance on others for approval, identity, and self-worth — typically at the expense of one’s own needs, boundaries, and sense of self.

Mental Health America describes it as a “relationship addiction”: a pattern where people form or maintain relationships that are one-sided, emotionally exhausting, and often damaging — yet feel compelled to stay because their sense of purpose and worth has become fused with the relationship itself.

Importantly, current research frames codependency not as a character flaw or a deliberate choice, but as a learned relational strategy — one that almost always has its roots in early experiences where a child learnt that to be loved, they needed to be needed.

The Difference Between Normal Relationship Behaviour and Codependency

This is perhaps the most important clinical question, and one that causes enormous confusion. Most people, at some point in a relationship, will:

• Put their partner’s needs before their own
• Worry excessively about someone they love
• Suppress their own feelings to keep the peace
• Feel their mood affected by their partner’s emotional state
• Struggle to maintain boundaries with someone they care about deeply

None of these, in isolation or temporarily, constitute codependency. Relationships involve genuine interdependence — research by Rusbult and Van Lange (2003) in the Annual Review of Psychology demonstrates that healthy mutual reliance is not only normal but essential to human flourishing. We are wired for attachment, and feeling affected by those we love is a feature of that, not a flaw.

The distinction lies in pattern, pervasiveness, proportion, and — critically — motivation.

In healthy relationships, care for another is chosen freely from a stable sense of self. You can be deeply affected by your partner’s pain without feeling responsible for fixing it. You can prioritise their needs without abandoning your own. You can be close without losing the thread of who you are.

In codependent relationships, the dynamic is structurally different. The table below outlines the key distinctions that clinicians look for:

That last row is one of the most clinically telling features of codependency. When a codependent person’s partner recovers, stabilises, or no longer needs them in the same way, it can trigger a profound identity crisis — because the caretaking role was not just something they did; it was who they were.

Evidence-Based Signs You May Be in a Codependent Relationship

The following indicators are drawn from validated clinical frameworks, including the work of Darlene Lancer (a leading researcher in codependency treatment), the Codependency Assessment Tool (CAT), and broader attachment and self-determination research.

1. Your emotional state is governed by the other person’s

You feel happy when they are happy, anxious when they are struggling, guilty when they are upset — regardless of whether you had any role in it. Their mood functions as the weather system you live inside. This is clinical enmeshment: a blurring of the emotional boundary between self and other.

2. You feel responsible for managing their emotions

Not just concerned — responsible. You find yourself working to regulate their feelings, prevent their distress, or shield them from the consequences of their behaviour. You walk on eggshells. You rehearse conversations. You adjust yourself to pre-empt their reactions.

3. Your self-worth is tied to being needed or useful

You feel most secure, most loveable, most like “yourself” when the other person is relying on you. When they don’t need you — when they are doing well, managing independently, or connecting with others — you feel vaguely anxious, unsettled, or unnecessary.

4. You have significant difficulty saying no

Not simply a preference for harmony, but a deep fear of what will happen if you assert a need, a limit, or a disagreement. Saying no feels dangerous — not mildly uncomfortable, but genuinely threatening to your sense of safety in the relationship.

5. Your own needs feel unimportant, illegitimate, or too much to ask

You consistently prioritise the other person’s needs, minimise your own, and feel guilty or ashamed for having them at all. Other people’s needs feel urgent and real; yours feel like an inconvenience.

6. You enable behaviour that harms the other person (or you)

You cover for them, make excuses, absorb consequences, or rescue them from situations they need to face. You know, somewhere, that this is not helping — but stopping feels impossible, cruel, or too frightening.

7. The relationship has become your primary source of identity

Outside of this relationship, you are not sure who you are, what you want, or what matters to you. Your social connections, interests, and sense of purpose have narrowed to the point where the relationship has become your whole world.

8. You experience disproportionate fear of the relationship ending

Beyond the normal grief of losing someone important, the prospect of this relationship ending feels like annihilation — as though without it, you would cease to exist in any meaningful sense.

What Causes Codependency? The Evidence

Current research strongly implicates early attachment experiences as the primary driver of codependent patterns. Studies in developmental psychology consistently show that children who grow up in environments characterised by:

• Emotional unpredictability or neglect
• A parent or caregiver with addiction, mental illness, or chronic instability
• Conditional love (affection given in exchange for performance, caretaking, or compliance)
• Parentification (being required to manage a parent’s emotional world)

…are significantly more likely to develop the relational strategies we now recognise as codependency. These children learn, at a pre-verbal and deeply embodied level, that love is not unconditional — that it must be earned through service, vigilance, or self-erasure.

Attachment theorists describe this as an anxious or disorganised attachment style: a chronic hypervigilance to the emotional states of others, combined with an unstable or underdeveloped sense of self.

Critically, Mental Health America notes that codependency is a multigenerational pattern — one that is modelled, transmitted, and reinforced across families and generations, often without anyone recognising it for what it is. This is why it so frequently feels normal. To the person in it, it simply feels like love.

How to Navigate a Codependent Relationship: What the Evidence Recommends

Recognising codependency is significant. What comes next matters enormously. The following steps reflect current evidence-based approaches, including schema therapy, attachment-focused therapy, and self-determination theory.

Step 1: Name it without shame

Codependency is not a character defect. It is a survival strategy that once served a purpose. The self-critical spiral of “why can’t I just stop?” is itself part of the pattern — a form of the same self-erasure that drives codependency in the first place. Begin by acknowledging what is true, with as much compassion as you can manage.

Step 2: Seek individual therapy — not couples therapy, at least not first

This is one of the most consistent recommendations in the clinical literature, and one of the most frequently ignored. The instinct in a codependent relationship is to focus on the relationship — to fix the dynamic, to work on “us.” But codependency is fundamentally an individual pattern that predates the current relationship. Individual therapy is the appropriate first step.

Evidence-based modalities with strong outcomes for codependency include:

• Schema Therapy: Identifies the early maladaptive schemas (core beliefs about self and relationships) that drive codependent behaviour, and systematically reworks them
• Attachment-focused therapy: Addresses the insecure attachment patterns at the root of codependency, building what attachment researchers call “earned security”
• Acceptance and Commitment Therapy (ACT): Builds psychological flexibility, value-based action, and a stable sense of self that does not depend on external validation
• Dialectical Behaviour Therapy (DBT): Particularly helpful where emotional dysregulation and enmeshment are prominent features

Step 3: Begin the work of differentiation

Differentiation — the developmental process of becoming a distinct self within a close relationship — is at the heart of codependency recovery. In practical terms, this means:

• Identifying your own feelings, needs, and values separately from the other person’s
• Practising sitting with the other person’s distress without rushing to fix it
• Rebuilding connections, interests, and a sense of identity outside the relationship
• Gradually practising the expression of needs and limits — starting small, building tolerance

This is not a process of becoming cold or detached. Research on interdependence consistently shows that the more securely differentiated a person is, the more genuinely intimate they can be. As The Bridge to Recovery notes, this is what attachment researchers call the “dependency paradox”: the more safely you can depend on someone, the freer and more authentically connected you become.

Step 4: Address enabling behaviours directly

If the relationship involves someone with an addiction, mental health condition, or chronic instability, the codependent person is almost certainly engaging in enabling — behaviours that, with the best of intentions, prevent the other person from experiencing the natural consequences that might otherwise motivate change.

This is extraordinarily difficult to stop, not because the person doesn’t understand it intellectually, but because it is underpinned by deep anxiety and a terror of what will happen if they don’t intervene. Therapeutic support is usually required to navigate this safely.

Step 5: Consider whether the relationship can become healthy

This is a question that must be held with honesty. Some relationships, with both parties doing meaningful work, can move from codependency toward genuine interdependence. This typically requires both people to be willing to acknowledge the dynamic, engage in individual therapeutic work, and — often — couples therapy once both have established some individual stability.

Other relationships cannot sustain that shift. If the other person has no interest in change, or if the dynamic is also characterised by coercive control, abuse, or sustained exploitation, the most honest clinical recommendation is that the healthiest path forward may be to leave.

This is not a failure. It is, in many cases, the most courageous and self-respecting act available.

Step 6: Build the life you paused

Recovery from codependency is not simply the removal of a problematic pattern. It is the construction of something new: a stable, internally anchored sense of self; relationships characterised by genuine reciprocity; a life in which your own needs, values, and wellbeing are not an afterthought but a foundation.

This takes time. It is not linear. But the research is clear that it is possible — and that the therapeutic work, while challenging, produces lasting and meaningful change.

A Note on Seeking Support in Australia

If you recognise yourself in this article, please know that you are not alone and that effective help is available. A number of pathways are worth considering:

• Individual therapy with a psychologist or psychotherapist experienced in attachment, schema, or relational trauma
• SANE Australia (sane.org) — mental health support and resources
• Beyond Blue (beyondblue.org.au) — resources and access to counselling
• Co-Dependents Anonymous (CoDA) Australia — a peer support programme based on the 12-step model, with meetings available nationally and online

The fact that you are asking these questions is already significant. Awareness is where change begins.

Mitchell Webb is a counsellor and psychotherapist based in Surry Hills, Sydney, with a focus on relational patterns, attachment, and identity. Webb Therapy offers individual counselling and psychotherapy for adults navigating complex relationship dynamics.

References

American Psychological Association. (2023). APA Dictionary of Psychology. apa.org

Mental Health America. Codependency. mhanational.org

Rusbult, C. E., & Van Lange, P. A. M. (2003). Interdependence, interaction, and relationships. Annual Review of Psychology, 54(1), 351–375.

Feeney, B. C., & Van Vleet, M. (2010). Growing through attachment: The interplay of attachment and exploration in adulthood. Journal of Social and Personal Relationships, 27(2), 226–234.

Lancer, D. (2014). Conquering shame and codependency. Hazelden Publishing.

Young, J. E., Klosko, J. S., & Weishaar, M. E. (2003). Schema therapy: A practitioner’s guide. Guilford Press.