* An overlapping cluster of phobias embracing fears of leaving home: fear of entering shops, crowds, open spaces and public places, or of travelling alone in trains, buses, or planes.
* Can also mean fear faced with a difficulty of immediate easy escape to a safe place (usually home).
* Considered the most incapacitating of the phobic disorders and some sufferers become completely housebound.
* Most sufferers are women and the onset is usually early in adult life.
2. Anxiety (generalised anxiety disorder)
* General anxiety is persistent but not restricted to, or necessarily dominant any in particular environmental circumstances. It is – "free-floating".
* Continuous feelings of nervousness, trembling, muscular tension, sweating, lightheadedness, palpitations, dizziness, and gastric discomfort such as bloating or abdominal pain are common.
* Fears that the sufferer or a relative will shortly become ill or have an accident are often expressed, together with a variety of other worries and forebodings.
* This disorder is more common in women, and often related to chronic environmental stress. Its course is variable but tends to be fluctuating and chronic.
3. Anorexia nervosa
* Deliberate weight loss that is induced and sustained by the patient.
* Most common in adolescent girls and young women, but adolescent boys and young men may be affected, as may children approaching puberty and older women up to the menopause.
* Physical, behavioural and psychological evidence that the use of a substance has taken on a greater priority than other behaviours that once had a greater value.
5. Emotionally unstable personality disorder
* Alternating manic and depressive episodes separated by periods of normal mood.
* There are usually chronic feelings of emptiness.
* A tendency to become involved in intense and unstable relationships, thought to be associated with excessive efforts to avoid abandonment.
* The patient's own self-image, aims, and internal preferences are often unclear or disturbed.
* A strong tendency to act impulsively without consideration of the consequences, together with repeated and abrupt shifts in mood.
* The patient may struggle to plan ahead.
* Outbursts of intense anger may often lead to violence or "behavioural explosions", often as a result of others criticising or trying to prevent impulsive acts.
* Manic mood and associated grandiose behaviour can often be accompanied by agitation and loss of energy and libido.
* Symptoms of depression can alternate as rapidly as from day to day or hour to hour.
* Can also be known as "borderline personality disorder".
6. Body Dysmorphic Disorder
* A persistent preoccupation with a presumed deformity or disfigurement even though these beliefs cannot be physically proven.
* Depression and anxiety are often present, although these may justify additional diagnosis.
* Psychiatric referral is often resented, unless accomplished early in the development of the disorder and with tactful collaboration between physician and psychiatrist.
* Considered to be a specific form of hypochondriacal disorder.
7. Bulimia nervosa
* Repeated bouts of overeating and an excessive preoccupation with the control of body weight are followed by extreme efforts to counter the effect of having eaten "fattening" food.
* This can involve vomiting or other measures such as taking laxatives.
* Shares similar thought processes with anorexia, and can appear in previously anorexic patients when a pattern of overeating and vomiting becomes established following weight gain.
* A loss of interest and enjoyment, and reduced energy leading to increased tendency to become tired and avoid activity.
* Tiredness after even only slight effort is common.
* Other common symptoms include difficulty with concentration or paying attention, ideas of guilt and unworthiness, bleak and pessimistic views of the future, disturbed sleep and reduced appetite.
* Ideas of acts of self-harm or taking ones own life can be present.
* Lowered mood tends not to vary from day-to-day although can often improve as the day goes on.
* A duration of low mood for two weeks is usually required for diagnosis unless the symptoms are especially severe and the onset has been rapid.
9. Dissociative disorders
* A partial or complete loss of the normal integration between memories of the past, awareness of identity, immediate sensations, and control of bodily movements.
* An inability to exercise a conscious and selective control over memories.
* Often associated closely in time with traumatic events, insoluble and intolerable problems, or disturbed relationships.
* Bereavements, accidents, and other emotionally distressing events may be followed by a "reactive" overeating, possibly leading to obesity, especially in individuals predisposed to weight gain.
* A patient could develop a sensitivity about his or her appearance as a result of weight gain, which could lead to lack of confidence or ability to subjectively appraise body size.
* Overeating can be related to other anxious or depressive disorders.
* An unsatisfactory quantity and/or quality of sleep, which persists for a considerable period of time.
* Difficulty falling asleep, difficulty staying asleep and waking hours earlier than usual are common complaints of insomniacs.
* While reduced quantity of sleep is a problem for some, others are able to function well on little sleep, and others may not have a change in amount of sleep, but find that it lacks quality, so individual differences must be taken into account.
* Insomnia is associated with increased stress.
* A fear of sleeplessness and a preoccupation with its consequences can occur as a result of insomnia.
* Individuals with insomnia describe themselves as feeling tense, anxious, worried, or depressed at bedtime, and as though their thoughts are racing.
* Using medication or alcohol to cope with insomnia is common.
* Dreams that are filled with anxiety or fear, of which the individual has very detailed recall.
* The vivid dreams tend to involve threats to survival, security, or self-esteem, and will often have recurring themes.
* A person will be especially alert and orientated when they awake from a nightmare.
* Nightmares in children tend to be associated with emotional development but in adults, psychological disturbance is often present, usually in the form of a personality disorder.
* The use of certain psychotropic drugs such as reserpine, thioridazine, tricyclic antidepressants, and benzodiazepines has also been found to contribute to the occurrence of nightmares.
13. Obsessive compulsive disorder (OCD)
* Recurrent obsessional thoughts or compulsive acts are the defining factors of OCD.
* Obsessional thoughts are ideas, images or impulses that enter the individual's mind again and again in a stereotyped form.
* The thoughts tend to be distressing, but are considered to be the patients own thoughts, rather than "voices" associated with schizophrenia.
* Compulsive acts or rituals are stereotyped behaviours that are repeated again and again.
* Rituals are not inherently enjoyable, nor do they result in the completion of inherently useful tasks.
* It is often thought by the patient that carrying out these rituals will prevent an objectively unlikely event that could involve harm to them or others.
* While accompanying symptoms of anxiety are often also present, obsessive thoughts can occur without any obvious sign of distress.
* There is a close relationship between obsessive compulsive disorder, particularly obsessional thoughts, and depression.
14. Panic disorder
* Recurrent attacks of severe anxiety (panic) which are not restricted to any particular situation or set of circumstances, and which are therefore unpredictable.
* Sudden onset of palpitations, chest pain, choking sensations, dizziness, and feelings of unreality are common.
* Secondary fear of dying, losing control, or going mad can occur as a result of panic attacks.
* When a panic attack occurs, a patient will usually try to hurriedly exit the environment they're in. This may lead them to avoid those places (for example buses or crowded places) in future.
* A panic attack is often followed by a persistent fear of having another attack.
* Fear that is restricted to highly specific things and situations such as particular animals, heights, thunder, darkness, flying, closed spaces, foods, the sight of blood or injury, and the fear of exposure to specific diseases.
* Phobia triggers can provoke panic and similar symptoms to agoraphobia.
* While phobias will often arise in childhood, they can persist for decades if not treated.
* In contrast to agoraphobia or panic disorder, the level of fear of the phobic situation does not tend to vary.
16. Post-traumatic stress disorder (PTSD)
* A delayed response to a stressful situation or event of an exceptionally threatening or catastrophic nature. Combat, witnessing a violent death, being the victim of rape, or being in a serious accident are common pre-cursors to PTSD.
* Patients may experience a repeated reliving of the traumatic events as intrusive memories, known as "flashbacks" or dreams, alternating with numbness, emotional blunting and detachment from people.
* Situations and places that may remind the patient of an emotional trauma, for example the scene of a crime, can provoke fear and are often avoided.
* Anxiety, depression, insomnia and suicidal thoughts often accompany PTSD.
* The onset can occur a few weeks or a few months after the initial trauma, but tends not to occur after more than six months have passed.
* Distortions of thinking and perception.
* Hallucinations, especially auditory, (sometimes described as hearing voices) are common and may comment on the individual's behaviour or thoughts.
* Patients may feel like other people know what they are thinking.
* They often develop delusions to explain this. A patient might think that natural or supernatural forces are at work to influence their thoughts and actions in ways that are often considered bizarre.
* Perception can also be distorted in other ways, such as colours seeming more vividly, or an irrelevant detail on an object seeming to be the most important.
* They may believe that everyday situations possess a special, sometimes sinister, significance to them as an individual.
* Breaks in the patient's train of thought can be common and mood is often shallow or incongruous to a situation.
* Clear consciousness and intellectual capacity are usually maintained.
18. Social anxiety disorder (social phobia)
* Anxiety specifically relating to fear of scrutiny by other people in comparatively small groups (as opposed to crowds).
* Usually leads to the avoidance of social situations.
* It can be specific to certain situations, such as public speaking, or certain people, or can relate to all social situations.
* Often accompanied by a fear of vomiting.
* Some people may find eye contact especially stressful.
* Social phobias are usually associated with low self-esteem.
* A response to exceptional physical or mental pressure in individuals without any other apparent mental illness.
* A state of daze or narrowing attention may be present following an overwhelming traumatic experience.
* Physical signs of anxiety such as sweating may be present.
* Generally occurs immediately after the stressful event but disappears within 2-3 days.
*These definitions are paraphrased from World Health Organisation's ICD-10 Classification of Mental and Behavioural Disorders, the guidelines used by doctors in the UK to diagnose mental illness, according to the Department of Health, as of December 2015.
Emotionally unstable personality disorder and borderline personality disorder are both the same diagnosis. A previous version of this article listed them as separate conditions.
Laura Silver is a reporter for BuzzFeed News and is based in London.
Contact Laura Silver at firstname.lastname@example.org.
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