OCD, Eating Disorders, and the Brain: Unraveling the Neuroscience Behind the Struggle

Mental health conditions like Obsessive-Compulsive Disorder (OCD) and eating disorders are often seen as distinct challenges. However, beneath the surface, they share surprising similarities, especially when it comes to the brain’s wiring. Both disorders can be deeply distressing and disrupt daily life, but what makes them even more complex is their neurological overlap. 

Let’s look more closely at the neuroscience behind OCD and eating disorders, exploring how overactive brain circuits drive repetitive behaviors, whether it’s the compulsion to check, clean, or restrict food intake. As we unravel the shared neural mechanisms, we’ll also look at why these conditions often co-occur and how understanding the brain’s role is helping pave the way for more effective treatments. 

In honor of OCD Awareness Week, let’s raise awareness about these interlinked disorders and the hope for recovery through modern science.

What is OCD?

Obsessive-Compulsive Disorder (OCD) is a mental health condition characterized by two main features: obsessions and compulsions. 

Obsessions are intrusive, unwanted thoughts, images, or urges that cause intense anxiety or distress. These obsessions often feel impossible to control, despite the individual’s awareness that they are irrational. 

Compulsions, on the other hand, are repetitive behaviors or mental acts performed in response to the distress caused by the obsessions. People with OCD feel driven to perform these compulsive actions—such as excessive hand washing, checking locks, or counting—to temporarily relieve their anxiety. Unfortunately, these behaviors only reinforce the obsessions over time, creating a vicious cycle that can consume hours of a person’s day.

OCD impacts daily functioning in significant ways. It can disrupt work, school, relationships, and personal well-being. For some, the rituals or mental routines become so time-consuming that they struggle to maintain basic daily responsibilities. Others might avoid situations that trigger their obsessions, leading to isolation and heightened anxiety.

As we mark OCD Awareness Week, it’s important to recognize not only the emotional toll of this disorder but also the growing understanding of its neurological roots. The brain plays a central role in perpetuating OCD’s intrusive thoughts and compulsive actions, and unraveling these mechanisms is key to developing better treatments for those affected.

The Neuroscience of OCD

Obsessive-Compulsive Disorder (OCD) is more than just a mental struggle—it’s deeply rooted in the brain’s functioning. Recent advances in neuroscience have highlighted the key brain regions and neural circuits responsible for the intrusive thoughts and repetitive behaviors that define OCD.

Key Brain Regions Involved

Three critical brain areas have been linked to OCD:

• Orbitofrontal Cortex (OFC): This region is involved in decision-making, reward processing, and anxiety regulation. In OCD, the OFC becomes overactive, leading to heightened concern about potential threats (such as contamination or danger) and triggering compulsive behaviors aimed at preventing these threats.
• Anterior Cingulate Cortex (ACC): The ACC plays a role in error detection and emotional regulation. People with OCD often experience a constant feeling that something is "wrong" or incomplete, which is linked to heightened activity in the ACC. This hyperactivity fuels the need to perform repetitive behaviors in an attempt to "correct" perceived errors.
• Basal Ganglia: This area is crucial in habit formation and motor control. In OCD, dysfunctional communication between the basal ganglia and other parts of the brain contributes to the persistence of compulsions, making these behaviors difficult to stop once they’re set in motion.

Overactive Neural Circuits

At the core of OCD is the malfunctioning of a brain circuit known as the cortico-striato-thalamo-cortical (CSTC) loop. This loop involves communication between the OFC, ACC, and basal ganglia. When this circuit becomes overactive, it generates intrusive thoughts (obsessions) and urges to perform compulsive behaviors. Essentially, the brain gets "stuck," repeating patterns of anxiety and relief through rituals, making it hard for individuals with OCD to break free from their compulsions.

The Role of Serotonin and Dopamine in OCD

Neurotransmitters, the brain’s chemical messengers, also play a major role in OCD. Two key neurotransmitters—serotonin and dopamine—are dysregulated in the disorder:

• Serotonin: Low levels or dysfunction in serotonin pathways contribute to the obsessive and anxious thoughts that dominate OCD. Medications that increase serotonin levels, such as selective serotonin reuptake inhibitors (SSRIs), have been shown to reduce symptoms in many individuals with OCD, suggesting that serotonin plays a key role in managing intrusive thoughts.
• Dopamine: This neurotransmitter is involved in the brain’s reward system and reinforces behaviors. In OCD, an imbalance in dopamine levels can lead to the reinforcement of compulsive actions, making it difficult for individuals to resist their urges despite knowing that their behaviors are irrational.

Understanding the brain regions and chemical imbalances involved in OCD provides a clearer picture of why individuals feel trapped in cycles of obsession and compulsion. This knowledge also forms the foundation for developing targeted treatments, from medication to specialized therapies that aim to recalibrate these malfunctioning circuits.

The Neuroscience of Eating Disorders

Eating disorders are complex mental health conditions that involve unhealthy relationships with food, body image, and weight. They can take various forms, including 

• anorexia nervosa 
• bulimia nervosa 
• binge eating disorder 
• ARFID

Each of these has distinct behaviors but is rooted in similar psychological and neurological mechanisms. These disorders are not just about food—they are deeply intertwined with emotions, self-perception, and brain function.

Research has revealed that specific brain regions are involved in the development and maintenance of eating disorders:

• Insula: This region plays a key role in the awareness of body sensations, such as hunger and fullness. In eating disorders, the insula may misinterpret these signals, leading individuals to ignore hunger cues or feel discomfort after eating.
• Prefrontal Cortex: Responsible for decision-making and impulse control, the prefrontal cortex helps regulate behavior. In eating disorders, this region’s functioning may be altered, leading to poor decision-making around food and difficulty controlling urges to restrict, binge, or purge.
• Amygdala: This part of the brain is involved in processing emotions, particularly fear and anxiety. In people with eating disorders, the amygdala may be overactive, contributing to heightened anxiety about weight gain or food consumption. Or due to a previous traumatic experience with food such as food poisoning. 

Hunger Cues, Body Image, and Reward Systems

Eating disorders distort the brain’s ability to process hunger cues, making it difficult for individuals to recognize when they need to eat or when they are full. This miscommunication can lead to both starvation and overeating. Additionally, body image disturbances are thought to result from abnormalities in the brain's visual processing areas and emotional centers, where the body is perceived as larger or more flawed than it truly is.

The brain's reward system—primarily governed by dopamine—also plays a crucial role. In conditions like anorexia, the reward centers may become less responsive to food, leading to a diminished sense of pleasure from eating. On the other hand, in binge eating disorder, the brain may seek food as a source of emotional comfort, reinforcing binge behaviors.

How OCD and Eating Disorders Overlap

Obsessive-Compulsive Disorder (OCD) and eating disorders, though distinct in many ways, share significant neurological and behavioral overlap. Both conditions involve repetitive, ritualized behaviors driven by a need to manage overwhelming anxiety. At their core, OCD and eating disorders often reflect an attempt to gain control over distressing thoughts and emotions through maladaptive behaviors. This shared mechanism points to underlying similarities in how the brain processes anxiety, fear, and reward, and how these processes manifest in both disorders.

Shared Brain Regions

One of the most striking overlaps between OCD and eating disorders is the involvement of similar brain regions, particularly the orbitofrontal cortex (OFC) and anterior cingulate cortex (ACC):

• In OCD, the OFC is hyperactive, driving the person to engage in compulsive behaviors to relieve anxiety triggered by intrusive thoughts.
• In eating disorders that include body-image and fear of weight gain as a symptom, the same brain region is involved in the rigid, obsessive focus on body image, weight, and food-related fears. The OFC helps reinforce behaviors like calorie restriction, just as it reinforces compulsive rituals in OCD.

The ACC, which is crucial for detecting errors and regulating emotions, is also overactive in both disorders. This heightened activity in the ACC leads to a persistent feeling of something being “wrong” that can only be “fixed” through repetitive behaviors—whether that’s checking in OCD or restricting calories or purging in eating disorders.

Compulsive Behaviors and the Brain’s Reward System

Both OCD and eating disorders engage the brain’s reward system, albeit in different ways, to reinforce compulsive behaviors:

• In OCD, the act of completing a ritual (like handwashing or checking) temporarily relieves anxiety, creating a cycle of reinforcement where the brain links the behavior to reduced distress.
• In eating disorders, behaviors like calorie restriction, bingeing, or purging can also activate the reward system, temporarily reducing anxiety about body image or emotional distress, thus reinforcing these harmful habits.

The brain’s dopamine system, responsible for processing reward and pleasure, plays a critical role in both disorders. In OCD, dopamine dysregulation strengthens the compulsive urge to perform rituals. Similarly, in eating disorders, dopamine can either drive disordered eating behaviors (in binge eating, for instance) or blunt the brain’s ability to find pleasure in food (in anorexia).

Control and Anxiety Regulation

A central feature of both OCD and eating disorders is a heightened need for control, which stems from the brain’s inability to regulate anxiety effectively:

• In OCD, individuals may feel the need to control their environment or thoughts through rituals to prevent feared outcomes, even when they know these fears are irrational.
• In eating disorders, individuals often feel that controlling food intake, body weight, or exercise is a way to manage anxiety, for example about their appearance or self-worth. Restrictive eating or purging behaviors, much like OCD rituals, become coping mechanisms for deeper emotional turmoil.

Both disorders also involve a fear of loss of control, which drives individuals to engage in repetitive, often self-destructive behaviors. For example, someone with anorexia might restrict food intake to manage anxiety about body image, or someone with ARFID may restrict due to anxiety about the texture of foods, just as someone with OCD might perform rituals to avoid perceived threats.

Shared Emotional Drivers

At the core of both OCD and eating disorders is a profound sense of anxiety. In both conditions, anxiety serves as the trigger for compulsive behaviors. These behaviors, whether in the form of restrictive eating or repetitive rituals, temporarily alleviate the distress but ultimately reinforce the cycle, making it difficult to break free without intervention.

Co-Occurrence and Treatment Implications

Obsessive-Compulsive Disorder (OCD) and eating disorders frequently co-occur, with research suggesting that over 25% of individuals with eating disorders may also experience OCD. This high rate of co-occurrence points to shared underlying mechanisms in the brain and offers important insights for treatment. 

Why OCD and Eating Disorders Often Co-Occur

The shared brain circuitry that drives repetitive behaviors and obsessive thoughts in both OCD and eating disorders likely contributes to their frequent co-occurrence. As we said before, both disorders are rooted in overactive neural circuits in key brain regions. These circuits create a heightened need for control and an inability to tolerate uncertainty, which can manifest as either OCD rituals or disordered eating behaviors.

Additionally, serotonin and dopamine dysregulation are common to both disorders. Serotonin, critical for mood regulation, is often imbalanced in OCD, leading to heightened anxiety and compulsions. In eating disorders, serotonin also plays a role in controlling appetite and impulse regulation, further linking the two disorders on a neurochemical level. Dopamine, which governs the brain’s reward system, reinforces both compulsive rituals in OCD and disordered eating behaviors, such as calorie restriction or binging.

Treatment Approaches for Co-Occurring OCD and Eating Disorders

Treating OCD and eating disorders when they occur together can be complex, but addressing both disorders concurrently is crucial for long-term recovery. Since the two conditions share common neural pathways and psychological patterns, integrated treatment approaches that target both sets of symptoms can be particularly effective.

• Cognitive Behavioral Therapy (CBT): CBT is a highly effective therapy for both OCD and eating disorders. In the context of co-occurrence, CBT can help individuals identify the underlying thoughts and fears driving both their OCD rituals and disordered eating behaviors. Through structured exercises, patients learn to challenge irrational beliefs about control, food, and body image, gradually replacing maladaptive behaviors with healthier coping strategies.
• Exposure Response Prevention (ERP): ERP, a subset of CBT, is particularly useful for OCD. It involves exposing individuals to the triggers of their obsessions without allowing them to engage in compulsive rituals. In the context of eating disorders, ERP can also be adapted to help individuals confront their fear of weight gain, food, or eating in a controlled manner. By reducing the anxiety associated with these fears, ERP can help break the cycle of avoidance and restriction that characterizes both disorders.
• Addressing Neurochemical Imbalances: Medications that regulate serotonin and dopamine levels, such as Selective Serotonin Reuptake Inhibitors (SSRIs), can be beneficial for treating both OCD and eating disorders. SSRIs are commonly prescribed to reduce the symptoms of OCD, and they can also help alleviate the obsessive focus on food, seen in eating disorders.
• Holistic and Multidisciplinary Treatment: Given the complexity of co-occurring OCD and eating disorders, it is essential to adopt a multidisciplinary approach that includes therapists, nutritionists, and medical professionals. Treatment plans should address both the psychological and physical aspects of the disorders, with a focus on promoting proper nourishment, reducing compulsive behaviors, and restoring emotional well-being.

The Importance of Treating Both Disorders Together

Treating OCD and eating disorders in isolation can be less effective, as the symptoms of one disorder often exacerbate the other. For instance, treating OCD without addressing an individual’s disordered eating patterns may lead to the persistence of rituals around food, weight, and body image. Similarly, addressing only the eating disorder may leave the underlying anxiety and compulsive tendencies of OCD untreated, resulting in a high risk of relapse.

By understanding the shared brain mechanisms behind OCD and eating disorders, treatment can be more targeted and comprehensive. Approaches like CBT and ERP, combined with medical interventions, offer hope for breaking the cycle of both disorders and improving long-term outcomes.

Hope for Recovery

While OCD and eating disorders can be deeply intertwined and challenging to manage, ongoing advancements in neuroscience and treatment approaches are helping to unravel these complex conditions. Understanding the brain’s role in reinforcing compulsive behaviors opens the door to more effective, science-based therapies. With the right support, individuals struggling with both OCD and eating disorders can break free from their patterns and reclaim control over their lives.

Reach out to us today to learn more about our Intensive Outpatient Program (IOP) and Partial Hospitalization Program (PHP). Together, we can help you find the help you need.