Nail biting, also known as onychophagy or onychophagia (or even erroneously onyhophagia), is an
oral
The word oral may refer to:
Relating to the mouth
* Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid
**Oral administration of medicines
** Oral examination (also known as an oral exam or or ...
compulsive
Compulsive behavior is defined as performing an action persistently and repetitively. Compulsive behaviors could be an attempt to make obsessions go away. The act is usually a small, restricted and repetitive behavior, yet not disturbing in a pa ...
habit
A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously. of biting one's
fingernails
A nail is a claw-like plate found at the tip of the fingers and toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer ...
. It is sometimes described as a
parafunctional activity A para-functional habit or parafunctional habit is the habitual exercise of a body part in a way that is other than the most common use of that body part. In dentistry, orthodontics, and oral and maxillofacial pathology, the body part in question i ...
, the common use of the mouth for an activity other than speaking, eating, or drinking.
Nail biting is very common, especially amongst children. 25–30 percent of children bite nails. More pathological forms of nails biting are considered an
impulse control disorder in the
DSM-IV-R and are classified under obsessive-compulsive and related disorders in the
DSM-5
The ''Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition'' (DSM-5), is the 2013 update to the '' Diagnostic and Statistical Manual of Mental Disorders'', the taxonomic and diagnostic tool published by the American Psychiatri ...
. The ICD-10 classifies the practice as "other specified behavioral and emotional disorders with onset usually occurring in childhood and adolescence". However, not all nail biting is pathological, and the difference between harmful obsession and normal behavior is not always clear.
The earliest reference to nail biting as a symptom of anxiety was in late sixteenth century in France.
Signs and symptoms
Nail biting usually leads to harmful effects to the fingers, like infections. These consequences are directly derived from the physical damage of biting or from the hands becoming an infection
vector
Vector most often refers to:
*Euclidean vector, a quantity with a magnitude and a direction
*Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism
Vector may also refer to:
Mathematic ...
. Moreover, it can also have a social impact, for example social withdrawal and avoiding handshakes.
[
The ten fingernails are usually equally bitten to approximately the same degree.] Often, the adjacent skin is bitten off, too, which is called perionychophagia, a special case of dermatophagia. Biting nails can lead to broken skin on the cuticle. When cuticles are improperly removed, they are susceptible to microbial and viral infection
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
s such as paronychia
Paronychia is an inflammation of the skin around the nail, which can occur suddenly, when it is usually due to the bacterium ''Staphylococcus aureus'', or gradually when it is commonly caused by the fungus ''Candida albicans''. The term is fro ...
. Saliva may then redden and infect the skin. In rare cases, fingernails may become severely deformed after years of nail biting due to the destruction of the nail bed.
Nail biting may have an association with oral problems, such as gingiva
The gums or gingiva (plural: ''gingivae'') consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.
Structure
The gums are part of the soft tissue lin ...
l injury, and malocclusion
In orthodontics, a malocclusion is a misalignment or incorrect relation between the teeth of the upper and lower dental arches when they approach each other as the jaws close. The English-language term dates from 1864; Edward Angle (1855-19 ...
of the anterior teeth
In dentistry, the term anterior teeth usually refers as a group to the incisors and canine teeth as distinguished from the posterior teeth, which are the premolars and molars. The distinction is one of anterior (front of the body) versus poste ...
. It can also transfer pinworm
Pinworm infection (threadworm infection in the UK), also known as enterobiasis, is a human parasitic disease caused by the pinworm. The most common symptom is itching in the anal area. The period of time from swallowing eggs to the appearanc ...
s or bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
buried under the surface of the nail from the anus region to the mouth.[ If the bitten-off nails are swallowed, stomach problems can occasionally develop.]
Nail-biting can be a source of guilt and shame feelings in the nail biter, a reduced quality of life
Quality of life (QOL) is defined by the World Health Organization as "an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards ...
, and increased stigmatization in the inner family circles or at a more societal level.
Related disorders
Other body-focused repetitive behavior
Body-focused repetitive behavior (BFRB) is an umbrella name for Impulse control disorder, impulse control behaviors involving Compulsive behavior, compulsively self-injury, damaging one's physical appearance or causing physical injury.
Body-focuse ...
s include excoriation disorder (skin picking), dermatophagia (skin biting), and trichotillomania
Trichotillomania (TTM), also known as hair-pulling disorder or compulsive hair pulling, is a mental disorder characterized by a long-term urge that results in the pulling out of one's own hair. A brief positive feeling may occur as hair is remov ...
(the urge to pull out hair), and all of them tend to coexist with nail biting. As an oral parafunctional activity, it is also associated with bruxism (tooth clenching and grinding), and other habits such as pen chewing and cheek biting.
In children nail biting most typically co-occurs with attention deficit hyperactivity disorder
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...
(75% of nail biting cases in a study),[ and other ]psychiatric disorder
A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitt ...
s including oppositional defiant disorder
Oppositional defiant disorder (ODD) is listed in the DSM-5 under ''Disruptive, impulse-control, and conduct disorders'' and defined as "a pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness". This behavior is us ...
(36%) and separation anxiety disorder
Separation anxiety disorder (SAD) is an anxiety disorder in which an individual experiences excessive anxiety regarding separation from home and/or from people to whom the individual has a strong emotional attachment (e.g., a parent, caregiver, ...
(21%).[ It is also more common among children and adolescents with ]obsessive–compulsive disorder
Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts and/or feels the need to perform certain routines repeatedly to the extent where it induces distress or impairs general ...
. Nail biting appeared in a study to be more common in men with eating disorders than in those without them.
Treatment
The most common treatment, which is cheap and widely available, is to apply a clear, bitter-tasting nail polish to the nails. Normally denatonium benzoate
Denatonium, usually available as denatonium benzoate (under trade names such as Denatrol, BITTERANT-b, BITTER+PLUS, ''Bitrex'', and ''Aversion'') and as denatonium saccharide (BITTERANT-s), is the most bitter chemical compound known, with bitter ...
is used, the most bitter chemical compound known. The bitter flavor discourages the nail-biting habit.
Behavioral therapy
Behaviour therapy or behavioural psychotherapy is a broad term referring to clinical psychotherapy that uses techniques derived from behaviourism and/or cognitive psychology. It looks at specific, learned behaviours and how the environment, or o ...
is beneficial when simpler measures are not effective. Habit Reversal Training (HRT), which seeks to unlearn the habit of nail biting and possibly replace it with a more constructive habit, has shown its effectiveness versus placebo in children and adults. A study in children showed that results with HRT were superior to either no treatment at all or the manipulation of objects as an alternative behavior, which is another possible approach to treatment. In addition to HRT, stimulus control therapy is used to both identify and then eliminate the stimulus that frequently triggers biting urges. Other behavioral techniques that have been investigated with preliminary positive results are self-help techniques, such as decoupling and the use of wristbands as non-removable reminders. More recently, technology companies have begun producing wearable devices and smart watch applications that track the position of users' hands but no research has been published so far.
Another treatment for chronic nail biters is the usage of a dental deterrent device that prevents the front teeth from damaging the nails and the surrounding cuticles. After about two months, the device leads to a full oppression of the nail biting urge.
Evidence on the efficacy of drugs is very limited, and they are not routinely used.[ A small ]double-blind
In a blind or blinded experiment, information which may influence the participants of the experiment is withheld until after the experiment is complete. Good blinding can reduce or eliminate experimental biases that arise from a participants' expec ...
randomized
In common usage, randomness is the apparent or actual lack of pattern or predictability in events. A random sequence of events, symbols or steps often has no order and does not follow an intelligible pattern or combination. Individual ra ...
clinical trial
Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, diet ...
in children and adolescents indicated that N- acetylcysteine, a glutathione
Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, pe ...
and glutamate modulator, could, in the short term only, be more effective than placebo in decreasing the nail-biting behavior.
Nail cosmetics can help to ameliorate nail biting social effects.
Independently of the method used, parental education is useful in the case of young nail biters to maximize the efficacy of the treatment programs, as some behaviors by the parents or other family members may be helping to perpetuate the problem.[ For example, punishments have been shown to be not better than placebo, and in some cases may even increase the nail biting frequency.][
]
Epidemiology
While it is rare before the age of 3,[ about 30 percent of children between 7 and 10 years of age and 45 percent of teenagers engage in nail biting.] Finally, prevalence decreases in adults.[ Figures may vary between studies, and could be related to geographic and cultural differences.][ The proportion of subjects that have ever had the habit (]lifetime prevalence
In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number o ...
) may be much higher than the proportion of current nail-biters ( time-point prevalence). Although there does not seem to be a gender correlation, results of epidemiological studies on this issue are not fully consistent.[ It may be underrecognized since individuals tend to deny or be ignorant of its negative consequences, complicating its diagnosis.] Having a parent with a mental disorder is also a risk factor
In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection.
Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often ...
.[
]
References
External links
*
{{Mental and behavioural disorders, selected = adult
Body-focused repetitive behavior
Conditions of the skin appendages
Fingers
Habit and impulse disorders
Nails (anatomy)
Neurocutaneous conditions
Pica (disorder)