Compulsive hoarding in its worst forms can cause fires, unsanitary conditions (such as rat and roach infestations), and other health and safety hazards.

Listed below are possible symptoms hoarders may experience:

- They hold onto a large number of items that most people would consider useless or worthless, such as:

- Junk mail, old catalogs, magazines, and newspapers

- Worn out cooking equipment

- Things that might be useful for making crafts

- Clothes that might be worn one day

- Broken things or trash

- "Freebies" or other promotional products

- Their home is cluttered to the point where many parts are inaccessible and can no longer be used for intended purposes. For example:

- Beds that cannot be slept in

- Kitchens that cannot be used for food preparation

- Tables, chairs, or sofas that cannot be used for dining or sitting

- Unsanitary bathrooms

- Tubs, showers, and sinks filled with items and can no longer be used for washing or bathing.

- Their clutter and mess is at a point where it can cause illness, distress, and impairment. As a result, they:

- Do not allow visitors in, such as family and friends, or repair and maintenance professionals, because the clutter embarrasses them

- Are reluctant or unable to return borrowed items

- Keep the shades drawn so that no one can look inside

- Get into a lot of arguments with family members regarding the clutter

- Are at risk of fire, falling, infestation, or eviction

- Often feel depressed or anxious due to the clutter

Some of the fundamental components of kleptomania include recurring intrusive thoughts, impotence to resist the compulsion to engage in stealing, and the release of pressure following the act. These symptoms suggest that kleptomania could be regarded as an obsessive-compulsive type of disorder.

People diagnosed with kleptomania often have other types of disorders involving mood, anxiety, eating, impulse control, and drug use. They also have great levels of stress, guilt, and remorse, and privacy issues accompanying the act of stealing. These signs are considered to either cause or intensify general comorbid disorders. The characteristics of the behaviors associated with stealing could result in other problems as well, which include social segregation and substance abuse. The many types of other disorders frequently occurring along with kleptomania usually make clinical diagnosis uncertain.

There is a difference between ordinary theft and kleptomania: "ordinary theft (whether planned or impulsive) is deliberate and is motivated by the usefulness of the object or its monetary worth," whereas with kleptomania, there "is the recurrent failure to resist impulses to steal items even though the items are not needed for personal use or for their monetary value."

Kleptomania or klopemania is the inability to refrain from the urge for stealing items and is usually done for reasons other than personal use or financial gain. First described in 1816, kleptomania is classified in psychiatry as an impulse control disorder. Some of the main characteristics of the disorder suggest that kleptomania could be an obsessive-compulsive spectrum disorder.

The disorder is frequently under-diagnosed and is regularly associated with other psychiatric disorders, particularly anxiety and eating disorders, and alcohol and substance abuse. Patients with kleptomania are typically treated with therapies in other areas due to the comorbid grievances rather than issues directly related to kleptomania.

Over the last 100 years, a shift from psychotherapeutic to psychopharmacological interventions for kleptomania has occurred. Pharmacological treatments using selective serotonin reuptake inhibitors (SSRIs), mood stabilizers and opioid receptor antagonists, and other antidepressants along with cognitive behavioral therapy, have yielded positive results.

For many years, hoarding has been listed as a symptom or a subtype of obsessive-compulsive disorder (OCD) and obsessive–compulsive personality disorder (OCPD). Obsessive-compulsive disorder is a type of anxiety disorder. People with OCD experience unwanted thoughts that incline them to do something repetitively. Some of these behaviors are excessive cleanliness and excessive toothbrushing. The current DSM says that an OCD diagnosis should be considered when:

- The hoarding is driven by fear of contamination or superstitious thoughts

- The hoarding behavior is unwanted or highly distressing

- The individual shows no interest in the hoarded items

- Excessive acquisition is only present if there is a specific obsession with a certain item

Compulsive hoarding does not seem to involve the same neurological mechanisms as more familiar forms of obsessive–compulsive disorder and does not respond to the same drugs, which target serotonin. In compulsive hoarding, the symptoms are presented in the normal stream of consciousness, and are not perceived as repetitive or distressing like in OCD patients. Despite statistics indicating that there is a prevalence of hoarding in 18% to 40% of patients with OCD, only 5% of compulsive hoarders experience symptoms of OCD. In another study, a sample of 217 patients diagnosed with significant hoarding, only 18% were diagnosed with OCD, as opposed to the 36% that were diagnosed with a major depressive disorder. There are significant differences and issues between the diagnostic features of compulsive hoarding and OCD which are being considered in a possible addition to the DSM-V of a new independent disorder such as compulsive hoarding. It is also said that there may be an overlap with a condition known as impulse control disorder (ICD), particularly when compulsive hoarding is linked to compulsive buying or acquisition behavior.

Recent findings suggest that there may be three types of hoarding: pure hoarding, hoarding plus OCD (i.e., co-morbid OCD), and OCD-based hoarding Given the aforementioned distinction, it was proposed to increase coverage of compulsive hoarding in the forthcoming Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-V), both by creating a distinct category for compulsive hoarding, provisionally named, Hoarding Disorder (either in the main manual under "obsessive-compulsive spectrum disorders" or in the appendix), and by including hoarding as a potential symptom of OCD.

An addictive personality refers to a particular set of personality traits that make an individual predisposed to developing addictions. This hypothesis states that there may be common personality traits observable in people suffering from addiction. Alan R. Lang of Florida State University, author of an addiction study prepared for the United States National Academy of Sciences, said, "If we can better identify the personality factors, they can help us devise better treatment and can open up new strategies to intervene and break the patterns of addiction."

Experts describe the spectrum of behaviors designated as addictive in terms of five interrelated concepts: patterns, habits, compulsions, impulse control disorders, and physical addiction.

Compulsive decluttering is a pattern of behavior that is characterized by an excessive desire to discard objects in one's home and living areas. Other terms for such behavior includes obsessive compulsive spartanism. The homes of compulsive declutterers are often empty. It is the antonym of compulsive hoarding.

Trichotillomania is classified as compulsive picking of hair of the body. It can be from any place on the body that has hair. This picking results in bald spots. Most people who have mild Trichotillomania can overcome it via concentration and more self-awareness.

Those that suffer from compulsive skin picking have issues with picking, rubbing, digging, or scratching the skin. These activities are usually to get rid of unwanted blemishes or marks on the skin. These compulsions also tend to leave abrasions and irritation on the skin. This can lead to infection or other issues in healing. These acts tend to be prevalent in times of anxiety, boredom, or stress.

Compulsions and addictions are intertwined and reward is one major distinction between an addiction and a compulsion (as it is experienced in obsessive-compulsive disorder). An addiction is, by definition, a form of compulsion, and both addictions and compulsions involve operant reinforcement; however, in addiction, the desire and motivation to use a substance or engage in a behavior arises because it is rewarding (i.e., the compulsions that occur in addiction develop through positive reinforcement). In contrast, someone who experiences a compulsion as part of obsessive-compulsive disorder may not perceive anything rewarding from acting on the compulsion. Often, it is a way of dealing with the obsessive part of the disorder, resulting in a feeling of relief (i.e., compulsions may also arise through negative reinforcement).

Deep brain stimulation to the nucleus accumbens, a region in the brain involved heavily in addiction and reinforcement learning, has proven to be an effective treatment of obsessive compulsive disorder.

People with HPD are usually high-functioning, both socially and professionally. They usually have good social skills, despite tending to use them to manipulate others into making them the center of attention. HPD may also affect a person's social and/or romantic relationships, as well as their ability to cope with losses or failures. They may seek treatment for clinical depression when romantic (or other close personal) relationships end.

Individuals with HPD often fail to see their own personal situation realistically, instead dramatizing and exaggerating their difficulties. They may go through frequent job changes, as they become easily bored and may prefer withdrawing from frustration (instead of facing it). Because they tend to crave novelty and excitement, they may place themselves in risky situations. All of these factors may lead to greater risk of developing clinical depression.

Additional characteristics may include:

- Exhibitionist behavior

- Constant seeking of reassurance or approval

- Excessive sensitivity to criticism or disapproval

- Pride of own personality and unwillingness to change, viewing any change as a threat

- Inappropriately seductive appearance or behavior of a sexual nature

- Using somatic symptoms (of physical illness) to garner attention

- A need to be the center of attention

- Low tolerance for frustration or delayed gratification

- Rapidly shifting emotional states that may appear superficial or exaggerated to others

- Tendency to believe that relationships are more intimate than they actually are

- Making rash decisions

- Blaming personal failures or disappointments on others

- Being easily influenced by others, especially those who treat them approvingly

- Being overly dramatic and emotional

Some people with histrionic traits or personality disorder change their seduction technique into a more maternal or paternal style as they age.

Compulsive checking can include compulsively checking items such as locks, switches, and appliances. This type of compulsion usually deals with checking whether harm to oneself or others is possible. Usually, most checking behaviors occur due to wanting to keep others and the individual safe.

People that suffer from compulsive counting tend to have a specific number that is of importance in the situation they are in. When a number is considered significant, the individual has a desire to do the behavior such as wiping ones face off the number of times that is significant. Compulsive counting can include instances of counting things such as steps, items, behaviors, and mental counting.

Compulsive repeating is characterized by doing the same activity multiple times over. These activities can include re-reading a part of a book multiple times, re-writing something multiple times, repeating routine activities, or saying the same phrase over and over.

Compulsive washing is usually found in individuals that have a fear of contamination. People that have compulsive hand washing behaviors wash their hands repeatedly throughout the day. These hand washings can be ritualized and follow a pattern. People that have problems with compulsive hand washing tend to have problems with chapped or red hands due to the excessive amount of washing done each day.

Codependency is a type of dysfunctional helping relationship where one person supports or enables another person's drug addiction, alcoholism, gambling addiction, poor mental health, immaturity, irresponsibility, or under-achievement. Among the core characteristics of codependency, the most common theme is an excessive reliance on other people for approval and a sense of identity.

Given its grassroots origin, the precise definition of codependency varies based on the source but can be generally characterized as a subclinical and situational or episodic behavior similar to that of dependent personality disorder. In its broadest definition, a codependent is someone who cannot function from their innate self and whose thinking and behavior is instead organized around another person, or even a process, or substance. In this context, people who are addicted to a substance, like drugs, or a process, like gambling or sex, can also be considered codependent. In its most narrow definition, it requires one person to be physically or psychologically addicted, such as to heroin, and the second person to be psychologically dependent on that behavior. Some users of the codependency concept use the word as an alternative to using the concept of dysfunctional families, without statements that classify it as a disease.

Borderline personality disorder may be characterized by the following signs and symptoms:

- Markedly disturbed sense of identity

- Frantic efforts to avoid real or imagined abandonment and extreme reactions to such

- Splitting ("black-and-white" thinking)

- Impulsivity and impulsive or dangerous behaviours

- Intense or uncontrollable emotional reactions that often seem disproportionate to the event or situation

- Unstable and chaotic interpersonal relationships

- Self-damaging behavior

- Distorted self-image

- Dissociation

- Frequently accompanied by depression, anxiety, anger, substance abuse, or rage

The most distinguishing symptoms of BPD are marked sensitivity to rejection or criticism, and intense fear of possible abandonment. Overall, the features of BPD include unusually intense sensitivity in relationships with others, difficulty regulating emotions, and impulsivity. Other symptoms may include feeling unsure of one's personal identity, morals, and values; having paranoid thoughts when feeling stressed; dissociation and depersonalization; and, in moderate to severe cases, stress-induced breaks with reality or psychotic episodes.

An addictive behavior is a behavior, or a stimulus related to a behavior (e.g., sex or food), that is both rewarding and reinforcing, and is associated with the development of an addiction. Addictions involving addictive behaviors are normally referred to as behavioral addictions.

One of the symptoms of conduct disorder is a lower level of fear. Research performed on the impact of toddlers exposed to fear and distress shows that negative emotionality (fear) predicts toddlers' empathy-related response to distress. The findings support that if a caregiver is able to respond to infant cues, the toddler has a better ability to respond to fear and distress. If a child does not learn how to handle fear or distress the child will be more likely to lash out at other children. If the caregiver is able to provide therapeutic intervention teaching children at risk better empathy skills, the child will have a lower incident level of conduct disorder.

A mnemonic that can be used to remember the characteristics of histrionic personality disorder is shortened as "PRAISE ME":

- Provocative (or seductive) behavior

- Relationships are considered more intimate than they actually are

- Attention-seeking

- Influenced easily by others or circumstances

- Speech (style) wants to impress; lacks detail

- Emotional lability; shallowness

- Make-up; physical appearance is used to draw attention to self

- Exaggerated emotions; theatrical

Antisocial personality disorder is defined by a pervasive and persistent disregard for morals, social norms, and the rights and feelings of others. Individuals with this personality disorder will typically have no compunction in exploiting others in harmful ways for their own gain or pleasure and frequently manipulate and deceive other people, achieving this through wit and a facade of superficial charm or through intimidation and violence. They may display , think lowly and negatively of others, and lack remorse for their harmful actions and have a callous attitude to those they have harmed. Irresponsibility is a core characteristic of this disorder: they can have significant difficulties in maintaining stable employment as well as fulfilling their social and financial obligations, and people with this disorder often lead exploitative, unlawful, or parasitic lifestyles.

Those with antisocial personality disorder are often impulsive and reckless, failing to consider or disregarding the consequences of their actions. They may repeatedly disregard and jeopardize their own safety and the safety of others and place themselves and others in danger. They are often aggressive and hostile and display a disregulated temper and can lash out violently with provocation or frustration. Individuals are prone to substance abuse and addiction, and the abuse of various psychoactive substances is common in this population. These behaviors lead such individuals into frequent conflict with the law, and many people with ASPD have extensive histories of antisocial behavior and criminal infractions stemming back before adulthood.

Serious problems with interpersonal relationships are often seen in those with the disorder. Attachments and emotional bonds are weak, and interpersonal relationships often revolve around the manipulation, exploitation, and abuse of others. While they generally have no problems in establishing relationships, they may have difficulties in sustaining and maintaining them. Relationships with family members and relatives are often strained due to their behavior and the frequent problems that these individuals may get into.

Not all mental health professionals agree about standard methods of treatment. Caring for an individual with a physical addiction is not necessarily treating a pathology. The caregiver may only require assertiveness skills and the ability to place responsibility for the addiction on the other. There are various recovery paths for individuals who struggle with codependency. For example, some may choose cognitive-behavioral psychotherapy, sometimes accompanied by chemical therapy for accompanying depression. There also exist support groups for codependency, such as Co-Dependents Anonymous (CoDA), Al-Anon/Alateen, Nar-Anon, and Adult Children of Alcoholics (ACoA), which are based on the twelve-step program model of Alcoholics Anonymous and Celebrate Recovery a Christian, Bible-based group. Many self-help guides have been written on the subject of codependency.

Sometimes an individual can, in attempts to recover from codependency, go from being overly passive or overly giving to being overly aggressive or excessively selfish. Many therapists maintain that finding a balance through healthy assertiveness (which leaves room for being a caring person and also engaging in healthy caring behavior) is true recovery from codependency and that becoming extremely selfish, a bully, or an otherwise conflict-addicted person is not. Developing a permanent stance of being a victim (having a victim mentality) would also not constitute true recovery from codependency and could be another example of going from one extreme to another. A victim mentality could also be seen as a part of one's original state of codependency (lack of empowerment causing one to feel like the "subject" of events rather than being an empowered actor). Someone truly recovered from codependency would feel empowered and like an author of their life and actions rather than being at the mercy of outside forces. A victim mentality may also occur in combination with passive–aggressive control issues. From the perspective of moving beyond victim-hood, the capacity to forgive and let go (with exception of cases of very severe abuse) could also be signs of real recovery from codependency, but the willingness to endure further abuse would not.

Unresolved patterns of codependency can lead to more serious problems like alcoholism, drug addiction, eating disorders, sex addiction, psychosomatic illnesses, and other self-destructive or self-defeating behaviors. People with codependency are also more likely to attract further abuse from aggressive individuals, more likely to stay in stressful jobs or relationships, less likely to seek medical attention when needed and are also less likely to get promotions and tend to earn less money than those without codependency patterns. For some people, the social insecurity caused by codependency can progress into full-blown social anxiety disorders like social phobia, avoidant personality disorder or painful shyness. Other stress-related disorders like panic disorder, depression or PTSD may also be present.

Television addiction is a proposed addiction model associated with maladaptive or compulsive behavior associated with watching television programming. The most recent medical review on this model concluded that pathological television watching behavior may constitute a true behavioral addiction, but indicated that much more research on this topic is needed to demonstrate this. The compulsion can be extremely difficult to control in many cases. The television addiction model has parallels to other forms of behavioral addiction, such as addiction to drugs or gambling, which are also forms of compulsive behavior.

Television addiction is not a diagnosable condition of DSM-IV.

Passive–aggressive personality disorder was listed as an Axis II personality disorder in the DSM-III-R, but was moved in the DSM-IV to Appendix B ("Criteria Sets and Axes Provided for Further Study") because of controversy and the need for further research on how to also categorize the behaviors in a future edition. According to DSM-IV, Passive–aggressive personality disorder is "often overtly ambivalent, wavering indecisively from one course of action to its opposite. They may follow an erratic path that causes endless wrangles with others and disappointment for themselves." Characteristic of these persons is an "intense conflict between dependence on others and the desire for self-assertion." Although exhibiting superficial bravado, their self-confidence is often very poor, and others react to them with hostility and negativity. This diagnosis is not made if the behavior is exhibited during a major depressive episode or can be attributed to dysthymic disorder.

People with BPD may feel emotions with greater ease, depth and for a longer time than others do. A core characteristic of BPD is affective instability, which generally manifests as unusually intense emotional responses to environmental triggers, with a slower return to a baseline emotional state. People with BPD often engage in idealization and devaluation of others, alternating between high positive regard for people and great disappointment in them. In Marsha Linehan's view, the sensitivity, intensity, and duration with which people with BPD feel emotions have both positive and negative effects. People with BPD are often exceptionally enthusiastic, idealistic, joyful, and loving. However, they may feel overwhelmed by negative emotions ("anxiety, depression, guilt/shame, worry, anger, etc."), experiencing intense grief instead of sadness, shame and humiliation instead of mild embarrassment, rage instead of annoyance, and panic instead of nervousness.

People with BPD are also especially sensitive to feelings of rejection, criticism, isolation, and perceived failure. Before learning other coping mechanisms, their efforts to manage or escape from their very negative emotions may lead to emotional isolation, self-injury or suicidal behavior. They are often aware of the intensity of their negative emotional reactions and, since they cannot regulate them, they shut them down entirely. This can be harmful to people with BPD, since negative emotions alert people to the presence of a problematic situation and move them to address it which the person with BPD would normally be aware of only to cause further distress. People with BPD may feel emotional relief after cutting themselves.

While people with BPD feel euphoria (ephemeral or occasional intense joy), they are especially prone to dysphoria (a profound state of unease or dissatisfaction), depression, and/or feelings of mental and emotional distress. Zanarini et al. recognized four categories of dysphoria that are typical of this condition: extreme emotions, destructiveness or self-destructiveness, feeling fragmented or lacking identity, and feelings of victimization. Within these categories, a BPD diagnosis is strongly associated with a combination of three specific states: feeling betrayed, "feeling like hurting myself", and feeling out of control. Since there is great variety in the types of dysphoria experienced by people with BPD, the amplitude of the distress is a helpful indicator of borderline personality disorder. In addition to intense emotions, people with BPD experience emotional "lability"; or in other words, changeability. Although the term emotional lability suggests rapid changes between depression and elation, the mood swings in people with this condition actually fluctuate more frequently between anger and anxiety and between depression and anxiety.

The Diagnostic and Statistical Manual of Mental Disorders revision IV (DSM-IV) describes passive–aggressive personality disorder as a "pervasive pattern of negativistic attitudes and passive resistance to demands for adequate performance in social and occupational situations."

Passive-aggressive behavior is the obligatory symptom of the passive–aggressive personality disorder. Persons with passive–aggressive personality disorder are characterized by procrastination, covert obstructionism, inefficiency and stubbornness.

While antisocial personality disorder is a mental disorder diagnosed in adulthood, it has its precedent in childhood. The DSM-5's criteria for ASPD require that the individual have conduct problems evident by the age of 15. Persistent antisocial behavior as well as a lack of regard for others in childhood and adolescence is known as conduct disorder and is the precursor of ASPD. About 25-40% of youths with conduct disorder will be diagnosed with ASPD in adulthood.

Conduct disorder (CD) is a disorder diagnosed in childhood that parallels the characteristics found in ASPD and is characterized by a repetitive and persistent pattern of behavior in which the basic rights of others or major age-appropriate norms are violated. Children with the disorder often display impulsive and aggressive behavior, may be callous and deceitful, and may repeatedly engage in petty crime such as stealing or vandalism or get into fights with other children and adults. This behavior is typically persistent and may be difficult to deter with threat or punishment. Attention deficit hyperactivity disorder (ADHD) is common in this population, and children with the disorder may also engage in substance abuse." CD is differentiated from oppositional defiant disorder (ODD) in that children with ODD do not commit aggressive or antisocial acts against other people, animals, and property, though many children diagnosed with ODD are subsequently rediagnosed with CD.

Two developmental courses for CD have been identified based on the age at which the symptoms become present. The first is known as the "childhood-onset type" and occurs when conduct disorder symptoms are present before the age of 10 years. This course is often linked to a more persistent life course and more pervasive behaviors, and children in this group express greater levels of ADHD symptoms, neuropsychological deficits, more academic problems, increased family dysfunction, and higher likelihood of aggression and violence. The second is known as the "adolescent-onset type" and occurs when conduct disorder develops after the age of 10 years. Compared to the childhood-onset type, less impairment in various cognitive and emotional functions are present, and the adolescent-onset variety may remit by adulthood. In addition to this differentiation, the DSM-5 provides a specifier for a callous and unemotional interpersonal style, which reflects characteristics seen in psychopathy and are believed to be a childhood precursor to this disorder. Compared to the adolescent-onset subtype, the childhood onset subtype, especially if callous and unemotional traits are present, tends to have a worse treatment outcome.

There are no specific criteria for "externalizing behavior" or "externalizing disorders." Thus, there is no clear classification of what constitutes an externalizing disorder in the DSM-5. Attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD), antisocial personality disorder(ASPD), pyromania, kleptomania, intermittent explosive disorder (IED), and substance-related disorders are frequently referred to as externalizing disorders. Disruptive mood dysregulation disorder has also been posited as an externalizing disorder, but little research has examined and validated it to date given its recent addition to the DSM-5, and thus, it is not included further herein.

Externalizing disorders often involve emotion dysregulation problems and impulsivity that are manifested as antisocial behavior and aggression in opposition to authority, societal norms, and often violate the rights of others. Some examples of externalizing disorder symptoms include, often losing one's temper, excessive verbal aggression, physical aggression to people and animals, destruction of property, theft, and deliberate fire setting. As with all DSM-5 mental disorders, an individual must have functional impairment in at least one domain (e.g., academic, occupational, social relationships, or family functioning) in order to meet diagnostic criteria for an externalizing disorder. Moreover, an individual's symptoms should be atypical for their cultural and environmental context and physical medical conditions should be ruled out before an externalizing disorder diagnosis is considered. Diagnoses must be made by qualified mental health professionals. DSM-5 classifications of externalizing disorders are listed herein, however, can also be used to classify externalizing disorders. More specific criteria and examples of symptoms for various externalizing disorders can be found in the DSM-5.