Onychophagia, commonly known as nail biting, is a body-focused repetitive behavior (BFRB) that involves the compulsive biting of the nails, including the nail plate, nail bed, and cuticles. This condition is most common among adolescents, with its prevalence decreasing as individuals age. Although nail biting may start as a harmless, temporary habit, it can persist and develop into a pathological behavior, leading to psychological, social, and medical consequences.

Etiology and Risk Factors

Onychophagia is often seen as a self-soothing behavior that may arise in response to emotional states such as anxiety, stress, or boredom. Research suggests that it may share neurobiological and genetic factors with other body-focused repetitive behaviors (BFRBs), like trichotillomania (hair-pulling) and skin picking. Studies also indicate a potential genetic link, with higher prevalence rates in individuals who have family members with similar compulsive behaviors.

While onychophagia is most commonly observed in adolescents, its prevalence tends to decrease with age. It is estimated that 25–30% of adolescents engage in nail-biting to some extent, with many outgrowing the behavior by early adulthood. However, for some individuals, nail-biting may persist and become chronic, leading to more severe consequences, including damage to the nails and surrounding tissues.

Psychiatric Comorbidities

Onychophagia is often associated with various psychiatric disorders, which may contribute to or worsen the behavior. The most commonly observed comorbidities include:

• Obsessive-Compulsive Disorder (OCD):  Individuals with onychophagia frequently exhibit characteristics of OCD, such as a strong urge to engage in repetitive behaviors.
• Anxiety Disorders: Nail biting is commonly triggered by anxiety, with individuals using the behavior as a coping mechanism to manage distress.
• Attention Deficit Hyperactivity Disorder (ADHD): Onychophagia is more prevalent in those with ADHD, potentially linked to impulsivity and difficulties with self-regulation.
• Tic Disorders: The behavior may also be associated with tic disorders, including Tourette syndrome, which involves involuntary, repetitive movements or sounds.

The genetic component of onychophagia is suggested by its familial occurrence. Some studies indicate that individuals with a family history of compulsive disorders may be at higher risk for developing nail biting.

Clinical Presentation and Diagnosis

Onychophagia typically presents as the repetitive biting or chewing of the nails, which may involve the nail plate, nail bed, and cuticle. The behavior is often habitual and automatic, occurring during moments of stress, boredom, or concentration. In more severe cases, the skin around the nails may become damaged, and individuals may bite into the nail bed, leading to bleeding and infection.

A related condition, onychotillomania, involves picking or manipulating the nails rather than biting them. While both onychophagia and onychotillomania are classified as body-focused repetitive behaviors, they differ in their physical manifestation, with onychophagia focused on biting and onychotillomania involving manipulation or picking of the nails.

Complications

While onychophagia is often considered a benign habit, it can lead to a range of complications, including:

• Infections: Continuous nail biting can lead to infections like paronychia (inflammation of the skin around the nails) and onychomycosis (fungal infections). Bacterial or fungal infections can develop in the wounds created by biting, causing pain, swelling, and pus formation.
• Gastrointestinal Problems: Swallowing bitten nails or fragments of nails may result in gastrointestinal disturbances, including nausea, stomach discomfort, and, in rare cases, more severe issues like intestinal obstructions.
• Dental Complications: Chronic nail biting may cause dental issues, such as teeth root resorption, which weakens the teeth, and temporomandibular joint (TMJ) dysfunction due to the repetitive motions involved.
• Psychosocial Impact: Onychophagia can cause significant emotional distress, especially in social situations. Individuals may feel embarrassed or self-conscious about the appearance of their nails, leading to social anxiety and a decreased quality of life.

Treatment and Management

Management of onychophagia typically involves addressing both the behavior and any underlying psychological conditions. Treatment plans are individualized and may include behavioral interventions, psychological therapies, pharmacotherapy, and preventive measures. Key strategies include:

• Behavioral Interventions:
  • Habit Reversal Training (HRT): A form of cognitive-behavioral therapy (CBT), HRT involves teaching individuals to recognize triggers for nail biting and engage in alternative, less harmful behaviors (e.g., clenching fists or squeezing a stress ball) when the urge arises.
  • Positive Reinforcement: Rewarding individuals for abstaining from nail biting can help reinforce non-biting behaviors. This may involve setting goals to gradually reduce the frequency of the behavior.
• Psychological Therapies:
  • Acceptance and Commitment Therapy (ACT): ACT helps individuals accept the urge to bite their nails without acting on it, promoting mindfulness and emotional regulation.
  • Cognitive-Behavioral Therapy (CBT): CBT focuses on identifying and altering cognitive patterns that trigger onychophagia, such as anxiety or negative thoughts, and replacing them with healthier coping mechanisms.
• Pharmacotherapy: Medications may be considered if the behavior is associated with underlying psychiatric conditions, such as OCD, anxiety, or ADHD. Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for OCD and anxiety-related nail biting.
• Nail Barriers and Preventive Measures: To reduce the physical act of nail biting, individuals can try keeping nails short or applying bitter-tasting nail polishes that deter the habit. These products, often available over-the-counter, provide an aversive taste when the nails are bitten, which can help interrupt the behavior.
• Family Therapy and Support: For children and adolescents, family therapy may be helpful in addressing any familial or environmental factors contributing to the behavior. Parental involvement can also assist the child in managing the behavior and reinforcing positive habits at home.

Conclusion

Onychophagia is a common but potentially disruptive behavior that can range from a mild habit to a chronic, pathological condition. Although the condition is primarily behavioral, it is frequently linked with psychological comorbidities such as obsessive-compulsive disorder (OCD), anxiety, and attention-deficit hyperactivity disorder (ADHD). Effective treatment requires a comprehensive approach, including cognitive-behavioral therapies, pharmacological interventions, and behavioral strategies. For individuals with severe cases, psychological support and social interventions may be necessary to address the emotional and social consequences of the condition, improving both psychological well-being and quality of life.

References

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