While not as profoundly disabling as the physical symptoms of these diseases, PBA can significantly influence individuals' social functioning and their relationships with others. Such sudden, frequent, extreme, uncontrollable emotional outbursts may lead to social withdrawal and interfere with activities of daily living, social and professional pursuits, and reduce overall healthcare. For example, patients with ALS and MS are often cognitively normal. However, the appearance of uncontrollable emotions is commonly associated with many additional neurological disorders such as attention deficit/hyperactivity disorder, Parkinson's disease, cerebral palsy, autism, epilepsy, and migraines. This may lead to severe embarrassment and avoidance of social interactions for the patient, which in turn impairs their coping mechanisms and their careers.

The cardinal feature of the disorder is a pathologically lowered threshold for exhibiting the behavioral response of laughter, crying, or both. An affected individual exhibits episodes of laughter and/or crying without an apparent motivating stimulus or in response to stimuli that would not have elicited such an emotional response before the onset of their underlying neurologic disorder. In some patients, the emotional response is exaggerated in intensity but is provoked by a stimulus with an emotional valence congruent with the character of the emotional display. For example, a sad stimulus provokes a pathologically exaggerated weeping response instead of a sigh, which the patient normally would have exhibited in that particular instance.

However, in some other patients, the character of the emotional display can be incongruent with, and even contradictory to, the emotional valence of the provoking stimulus or may be incited by a stimulus with no clear valence. For example, a patient may laugh in response to sad news or cry in response to stimuli with no emotional undertone, or, once provoked, the episodes may switch from laughing to crying or vice versa.

The symptoms of PBA can be severe, with persistent and unremitting episodes. Characteristics include:

- The onset can be sudden and unpredictable, and has been described by some patients as coming on like a seizure;

- The outbursts have a typical duration of a few seconds to several minutes; and,

- The outbursts may happen several times a day.

Many people with neurologic disorders exhibit uncontrollable episodes of laughing, crying, or both that are either exaggerated or contradictory to the context in which they occur. Where patients have significant cognitive deficits (e.g., Alzheimer's) it can be unclear whether it is true PBA as opposed to a grosser form of emotional dysregulation, but patients with intact cognition often report the symptom as disturbing. Patients report that their episodes are at best only partially amenable to voluntary control, and unless they experience a severe change of mental status, they often have insight into their problem and judge their emotional display as inappropriate and out of character. The clinical effect of PBA can be severe, with unremitting and persistent symptoms that can be disabling to patients, and may significantly affect quality of life for caregivers.

Conversion disorder begins with some stressor, trauma, or psychological distress. Usually the physical symptoms of the syndrome affect the senses or movement. Common symptoms include blindness, partial or total paralysis, inability to speak, deafness, numbness, difficulty swallowing, incontinence, balance problems, seizures, tremors, and difficulty walking. These symptoms are attributed to conversion disorder when a medical explanation for the afflictions cannot be found. Symptoms of conversion disorder usually occur suddenly. Conversion disorder is typically seen in individuals aged 10 to 35, and affects between 0.011% and 0.5% of the general population.

Conversion disorder can present with motor or sensory symptoms including any of the following:

Motor symptoms or deficits:

- Impaired coordination or balance

- Weakness/paralysis of a limb or the entire body (hysterical paralysis or motor conversion disorders)

- Impairment or loss of speech (hysterical aphonia)

- Difficulty swallowing (dysphagia) or a sensation of a lump in the throat

- Urinary retention

- Psychogenic non-epileptic seizures or convulsions

- Persistent dystonia

- Tremor, myoclonus or other movement disorders

- Gait problems (astasia-abasia)

- Loss of consciousness (fainting)

Sensory symptoms or deficits:

- Impaired vision (hysterical blindness), double vision

- Impaired hearing (deafness)

- Loss or disturbance of touch or pain sensation

Conversion symptoms typically do not conform to known anatomical pathways and physiological mechanisms. It has sometimes been stated that the presenting symptoms tend to reflect the patient's own understanding of anatomy and that the less medical knowledge a person has, the more implausible are the presenting symptoms. However, no systematic studies have yet been performed to substantiate this statement.

Conversion disorder presents with symptoms that typically resemble a neurological disorder such as stroke, multiple sclerosis, epilepsy or hypokalemic periodic paralysis. The neurologist must carefully exclude neurological disease, through examination and appropriate investigations. However, it is not uncommon for patients with neurological disease to also have conversion disorder.

In excluding neurological disease, the neurologist has traditionally relied partly on the presence of positive signs of conversion disorder, i.e. certain aspects of the presentation that were thought to be rare in neurological disease but common in conversion. The validity of many of these signs has been questioned, however, by a study showing that they also occur in neurological disease. One such symptom, for example, is "la belle indifférence", described in DSM-IV as "a relative lack of concern about the nature or implications of the symptoms". In a later study, no evidence was found that patients with functional symptoms are any more likely to exhibit this than patients with a confirmed organic disease. In DSM-V, "la belle indifférence" was removed as a diagnostic criteria.

Another feature thought to be important was that symptoms tended to be more severe on the non-dominant (usually left) side of the body. There have been a number of theories about this, such as the relative involvement of cerebral hemispheres in emotional processing, or more simply, that it was "easier" to live with a functional deficit on the non-dominant side. However, a literature review of 121 studies established that this was not true, with publication bias the most likely explanation for this commonly held view. Although agitation is often assumed to be a positive sign of conversion disorder, release of epinephrine is a well-demonstrated cause of paralysis from hypokalemic periodic paralysis.

Misdiagnosis does sometimes occur. In a highly influential study from the 1960s, Eliot Slater demonstrated that misdiagnoses had occurred in one third of his 112 patients with conversion disorder. Later authors have argued that the paper was flawed, however, and a meta-analysis has shown that misdiagnosis rates since that paper was published are around 4%, the same as for other neurological diseases.

A restricted or constricted affect is a reduction in an individual's expressive range and the intensity of emotional responses.

Reduced affect display, sometimes referred to as emotional blunting, is a condition of reduced emotional reactivity in an individual. It manifests as a failure to express feelings (affect display) either verbally or non-verbally, especially when talking about issues that would normally be expected to engage the emotions. Expressive gestures are rare and there is little animation in facial expression or vocal inflection. Reduced affect can be symptomatic of autism, schizophrenia, depression, posttraumatic stress disorder, depersonalization disorder, schizoid personality disorder or brain damage. It may also be a side effect of certain medications (e.g., antipsychotics and antidepressants). Individuals with blunted or flat affect show different regional brain activity when compared with typical individuals.

Reduced affect should be distinguished from apathy, which explicitly refers to a lack of emotion, whereas reduced affect is a lack of emotional expression regardless of whether emotion is actually reduced or not.

Emotional dysregulation (ED) is a term used in the mental health community to refer to an emotional response that is poorly modulated, and does not fall within the conventionally accepted range of emotive response.

Possible manifestations of emotional dysregulation include angry outbursts or behavior outbursts such as destroying or throwing objects, aggression towards self or others, and threats to kill oneself. These variations usually occur in seconds to minutes or hours. Emotional dysregulation can lead to behavioral problems and can interfere with a person's social interactions and relationships at home, in school, or at place of employment.

Emotional dysregulation can be associated with an experience of early psychological trauma, brain injury, or chronic maltreatment (such as child abuse, child neglect, or institutional neglect/abuse), and associated disorders such as reactive attachment disorder. Emotional dysregulation may present in people with psychiatric disorders such as attention deficit hyperactivity disorder, bipolar disorder, borderline personality disorder, narcissistic personality disorder, and complex post-traumatic stress disorder. ED is also found among those with autism spectrum disorders. In such cases as borderline personality disorder, hypersensitivity to emotional stimuli causes a slower return to a normal emotional state. This is manifested biologically by deficits in the frontal cortices of the brain.

Research has shown that failures in emotional regulation may be related to the display of acting out, externalizing disorders, or behavior problems. When presented with challenging tasks, children who were found to have defects in emotional regulation (high-risk) spent less time attending to tasks and more time throwing tantrums or fretting than children without emotional regulation problems (low-risk). These high-risk children had difficulty with self-regulation and had difficulty complying with requests from caregivers and were more defiant. Emotional dysregulation has also been associated with childhood social withdrawal. Common signs of emotional dysregulation in early childhood include isolation, throwing things, screaming, lack of eye contact, refusing to speak, rocking, running away, crying, dissociating, high levels of anxiety, or inability to be flexible.

Typical deficiencies may include problems identifying, processing, describing, and working with one's own feelings, often marked by a lack of understanding of the feelings of others; difficulty distinguishing between feelings and the bodily sensations of emotional arousal; confusion of physical sensations often associated with emotions; few dreams or fantasies due to restricted imagination; and concrete, realistic, logical thinking, often to the exclusion of emotional responses to problems. Those who have alexithymia also report very logical and realistic dreams, such as going to the store or eating a meal. Clinical experience suggests it is the structural features of dreams more than the ability to recall them that best characterizes alexithymia.

Some alexithymic individuals may appear to contradict the above-mentioned characteristics because they can experience chronic dysphoria or manifest outbursts of crying or rage. However, questioning usually reveals that they are quite incapable of describing their feelings or appear confused by questions inquiring about specifics of feelings.

According to Henry Krystal, individuals suffering from alexithymia think in an operative way and may appear to be superadjusted to reality. In psychotherapy, however, a cognitive disturbance becomes apparent as patients tend to recount trivial, chronologically ordered actions, reactions, and events of daily life with monotonous detail. In general, these individuals lack imagination, intuition, empathy, and drive-fulfillment fantasy, especially in relation to objects. Instead, they seem oriented toward things and even treat themselves as robots. These problems seriously limit their responsiveness to psychoanalytic psychotherapy; psychosomatic illness or substance abuse is frequently exacerbated should these individuals enter psychotherapy.

A common misconception about alexithymia is that affected individuals are totally unable to express emotions verbally and that they may even fail to acknowledge that they experience emotions. Even before coining the term, Sifneos (1967) noted patients often mentioned things like anxiety or depression. The distinguishing factor was their inability to elaborate beyond a few limited adjectives such as "happy" or "unhappy" when describing these feelings. The core issue is that people with alexithymia have poorly differentiated emotions limiting their ability to distinguish and describe them to others. This contributes to the sense of emotional detachment from themselves and difficulty connecting with others, making alexithymia negatively associated with life satisfaction even when depression and other confounding factors are controlled for.

Alexithymia is considered to be a personality trait that places affected individuals at risk for other medical and psychiatric disorders while reducing the likelihood that these individuals will respond to conventional treatments for the other conditions. Alexithymia is not classified as a mental disorder in the fourth edition of the "Diagnostic and Statistical Manual of Mental Disorders". It is a dimensional personality trait that varies in severity from person to person. A person's alexithymia score can be measured with questionnaires such as the Toronto Alexithymia Scale (TAS-20), the Bermond-Vorst Alexithymia Questionnaire (BVAQ), the Online Alexithymia Questionnaire (OAQ-G2) or the Observer Alexithymia Scale (OAS). It is distinct from the psychiatric personality disorders, such as antisocial personality disorder or borderline personality disorder, with which it shares some characteristics, and is likewise distinct from the abnormal conditions of sociopathy or psychopathy.

Alexithymia is defined by:

1. difficulty identifying feelings and distinguishing between feelings and the bodily sensations of emotional arousal

2. difficulty describing feelings to other people

3. constricted imaginal processes, as evidenced by a scarcity of fantasies

4. a stimulus-bound, externally oriented cognitive style.

In studies of the general population the degree of alexithymia was found to be influenced by age, but not by gender; the rates of alexithymia in healthy controls have been found at: 8.3%; 4.7%; 8.9%; and 7%. Thus, several studies have reported that the prevalence rate of alexithymia is less than 10%. A less common finding suggests that there may be a higher prevalence of alexithymia amongst males than females, which may be accounted for by difficulties some males have with "describing feelings", but not by difficulties in "identifying feelings" in which males and females show similar abilities.

Psychologist R. Michael Bagby and psychiatrist Graeme J. Taylor have argued that the alexithymia construct is strongly related (negatively) to the concepts of psychological mindedness and emotional intelligence and there is "strong empirical support for alexithymia being a stable personality trait rather than just a consequence of psychological distress". Other opinions differ and can show evidence that it may be state-dependent.

Bagby and Taylor also suggest that there may be two kinds of alexithymia, "primary alexithymia" which is an enduring psychological trait that does not alter over time, and "secondary alexithymia" which is state-dependent and disappears after the evoking stressful situation has changed. These two manifestations of alexithymia are otherwise called "trait" or "state" alexithymia.

TBI patients may have sensory problems, especially problems with vision; they may not be able to register what they are seeing or may be slow to recognize objects. Also, TBI patients often have difficulty with hand–eye coordination, causing them to seem clumsy or unsteady. Other sensory deficits include problems with hearing, smell, taste, or touch. Tinnitus, a ringing or roaring in the ears, may occur. A person with damage to the part of the brain that processes taste or smell may perceive a persistent bitter taste or noxious smell. Damage to the part of the brain that controls the sense of touch may cause a TBI patient to develop persistent skin tingling, itching, or pain. These conditions are rare and difficult to treat.

Witzelsucht (from the German "witzeln", meaning to joke or wisecrack, and "sucht", meaning addiction or yearning) is a set of rare neurological symptoms characterized by a tendency to make puns, or tell inappropriate jokes or pointless stories in socially inappropriate situations. A less common symptom is hypersexuality, the tendency to make sexual comments at inappropriate times or situations. Patients do not understand that their behavior is abnormal, therefore are nonresponsive to others' reactions. This disorder is most commonly seen in patients with frontal lobe damage, particularly right frontal lobe tumors or trauma. The disorder remains named in accordance with its reviewed definition by German neurologist Hermann Oppenheim; its first description as the less focused "Moria" ("stupidity"), by German neurologist Moritz Jastrowitz, was in 1888.

Due to similarity of symptoms of the disorder to the mannerisms of Batman's arch-rival Joker, it is sometimes known as 'The Joker Syndrome'

TBI may cause emotional or behavioral problems and changes in personality. Emotional symptoms that can follow TBI include emotional instability, depression, anxiety, hypomania, mania, apathy, irritability, and anger. TBI appears to predispose a person to psychiatric disorders including obsessive compulsive disorder, alcohol or substance abuse or substance dependence, dysthymia, clinical depression, bipolar disorder, phobias, panic disorder, and schizophrenia. About one quarter of people with TBI suffer from clinical depression, and about 9% suffer mania. The prevalence of all psychiatric illnesses is 49% in moderate to severe TBI and 34% in mild TBI within a year of injury, compared with 18% of controls. People with TBI continue to be at greater risk for psychiatric problems than others even years after an injury. Problems that may persist for up to two years after the injury include irritability, suicidal ideation, insomnia, and loss of the ability to experience pleasure from previously enjoyable experiences.

Behavioral symptoms that can follow TBI include disinhibition, inability to control anger, impulsiveness, lack of initiative, inappropriate sexual activity, and changes in personality. Different behavioral problems are characteristic of the location of injury; for instance, frontal lobe injuries often result in disinhibition and inappropriate or childish behavior, and temporal lobe injuries often cause irritability and aggression.

Witzelsucht can occur in the context of frontotemporal dementia, a neurological disorder resulting from degeneration of the frontal lobes and/or anterior temporal lobes. There are a range of neuropsychiatric symptoms associated with frontal lobe dementia, including progressive declines in social conduct, insight, and personal and emotional regulation and reactivity. The most common social changes that arise in patients include awkwardness, decreased propriety and manners, unacceptable physical boundaries, and/or improper verbal or physical acts. Childish, frivolous, or silly behavior is associated with damage to the right frontal, and most likely adjacent orbitofrontal lobe involvement. This can be associated with witzelsucht, as well as moria- a similar disorder resulting in childish euphoria and cheerful excitement.

Witzelsucht is considered a disorder of mirth or humor, which is distinct from disorders of laughter. Patients with witzelsucht are essentially insensitive to humor, but are capable of producing it while other patients excessively laugh, often at things that are not funny. The most common disorders of laughter are associated with pseudobulbar palsy, which can be caused by severe brain trauma, most commonly in the right hemisphere. Pathological laughter in this can be triggered by trivial stimuli, which could be disconnected from the underlying mood, and be combined with crying. Pathological laughter can also occur in the absence of pseudobulbar palsy. Gelastic (laughing) seizures are another neurological case of inappropriate or excessive laughter occurring in brief bursts. Treatment for these disorders can include antidepressants and antimanic agents.

Anosodiaphoria is a condition in which a person who suffers disability due to brain injury seems indifferent to the existence of their handicap. Anosodiaphoria is specifically used in association with indifference to paralysis. It is a somatosensory agnosia, or a sign of neglect syndrome. It might be specifically associated with defective functioning of the frontal lobe of the right hemisphere.

Joseph Babinski first used the term anosodiaphoria in 1914 to describe a disorder of the body schema in which patients verbally acknowledge a clinical problem (such as hemiparesis) but fail to be concerned about it. Anosodiaphoria follows a stage of anosognosia, in which there may be verbal, explicit denial of the illness, and after several days to weeks, develop the lack of emotional response. Indifference is different from denial because it implies a lack of caring on the part of the patient whom otherwise acknowledges his or her deficit.

Emotional detachment, in psychology, can mean two different things.

Emotional detachment can be a positive behavior which allows a person to react calmly to highly emotional circumstances/ individuals. Emotional detachment in this sense is a decision to avoid engaging emotional connections, rather than an inability or difficulty in doing so, typically for personal, social, or other reasons. In this sense it can allow people to maintain boundaries, psychic integrity and avoid undesired impact by or upon others, related to emotional demands. As such it is a deliberate mental attitude which avoids engaging the emotions of others.

This detachment does not necessarily mean avoiding empathy; rather it allows the person space needed to rationally choose whether or not to be overwhelmed or manipulated by such feelings. Examples where this is used in a positive sense might include emotional boundary management, where a person avoids emotional levels of engagement related to people who are in some way emotionally overly demanding, such as difficult co-workers or relatives, or is adopted to aid the person in helping others such as a person who trains himself to ignore the "pleading" food requests of a dieting spouse, or indifference by parents towards a child's begging.

Emotional detachment can also be used to describe what is often considered "emotional numbing", "emotional blunting", i.e., dissociation, depersonalization or in its chronic form depersonalization disorder. This type of emotional numbing or blunting is a disconnection from emotion, it is frequently used as a coping/ survival skill during traumatic childhood events such as abuse or severe neglect. Over time and with much use, this can become second nature when dealing with day to day stressors.

Emotional detachment often arises from psychological trauma and is a component in many anxiety and stress disorders. The person, while physically present, moves elsewhere in the mind, and in a sense is "not entirely present", making them sometimes appear preoccupied.

Thus, such detachment is often not as outwardly obvious as other psychiatric symptoms; people with this problem often have emotional systems that are in overdrive. They may have a hard time being a loving family member. They may avoid activities, places, and people associated with any traumatic events they have experienced. The dissociation can also lead to lack of attention and, hence, to memory problems and in extreme cases, amnesia.

A fictional description of the experience of emotional detachment experienced with dissociation and depersonalization was given by Virginia Woolf in "Mrs Dalloway". In that novel the multifaceted sufferings of a war veteran, Septimus Warren Smith, with post-traumatic stress disorder (as this condition was later named) including dissociation, are elaborated in detail. One clinician has called some passages from the novel "classic" portrayals of the symptoms.

There may be more than one reason to account for emotional detachment.

It is known that SSRI (selective serotonin reuptake inhibitor) antidepressants, after taken for a while or taken one after another (if the doctor is trying to see what works), can cause what is called "emotional blunting". In this instance, the individual in question is often unable to cry, even if he or she wants to.

In other cases, the person may seem fully present but operate merely intellectually when emotional connection would be appropriate. This may present an extreme difficulty in giving or receiving empathy and can be related to the spectrum of narcissistic personality disorder.

Emotional detachment also allows acts of extreme cruelty, such as torture and abuse, supported by the decision to not connect empathically with the person concerned. Social ostracism, such as shunning and parental alienation, are other examples where decisions to shut out a person creates a psychological trauma for the shunned party.

Considering these different definitions, the decision as to whether emotional detachment in any given set of circumstances is considered to be a positive or negative mental attitude is a subjective one, and therefore a decision on which different people may not agree.

A few possible explanations for anosodiaphoria exist:

1. The patient is aware of the deficit but does not fully comprehend it or its significance for functioning

2. May be related to an affective communication disorder and defective arousal. These emotional disorders cannot account for the verbal explicit denial of illness of anosognosia.

Other explanations include reduced emotional experience, impaired emotional communication, alexithymia, behavioral abnormalities, dysexecutive syndrome, and the frontal lobes.

Low frustration tolerance (LFT), or "short-term hedonism" is a concept utilized to describe the inability to tolerate unpleasant feelings or stressful situations. It stems from the feeling that reality should be as wished, and that any frustration should be resolved quickly and easily. People with low frustration tolerance experience emotional disturbance when frustrations are not quickly resolved. Behaviors are then directed towards avoiding frustrating events which, paradoxically, leads to increased frustration and even greater mental stress.

In REBT the opposite construct is "high frustration tolerance".

Symptoms are similar to those in multiple sclerosis and may include dementia, aphasia, seizures, personality changes, poor attention, tremors, balance instability, incontinence, muscle weakness, headache, vomiting, and vision and speech impairment.

Giggle incontinence, giggle enuresis or enuresis risoria is the involuntary release of urine in response to giggling or laughter. The bladder may empty completely or only partially.

Giggle incontinence is more common in children than adults, typically appearing at ages 5 to 7, and is most common in girls near the onset of puberty. The condition tends to improve with age, with fewer episodes during the teenage years, but may persist into adulthood. A survey of 99 student nurses indicated that about 25% had experienced such a wetting event during their lifetime, and about 10% were still susceptible in their late teens.

Giggle incontinence is a special form of urge incontinence, and is not the same as stress incontinence, which is generally brought on by participating in vigorous sport.

The frustration discomfort scale (FDS), a multidimensional measure for LFT, was developed using REBT theories.

These dimensions were labelled in four categories:

1. Emotional intolerance, involving intolerance of emotional distress.

2. Entitlement, involving intolerance of unfairness and frustrated gratification.

3. Discomfort intolerance, involving intolerance of difficulties and hassles.

4. Achievement, involving intolerance of frustrated achievement goals.

Psychogenic pain, also called psychalgia, is physical pain that is caused, increased, or prolonged by mental, emotional, or behavioral factors.

Headache, back pain, or stomach pain are some of the most common types of psychogenic pain. It may occur, rarely, in persons with a mental disorder, but more commonly it accompanies or is induced by social rejection, broken heart, grief, lovesickness, or other such emotional events.

Sufferers are often stigmatized, because both medical professionals and the general public tend to think that pain from psychological source is not "real". However, specialists consider that it is no less actual or hurtful than pain from other sources.

The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, "or described in terms of such damage"" (emphasis added). In the note accompanying that definition, the following can be found about pain that happens for psychological reasons:

Many people report pain in the absence of tissue damage or any likely pathophysiological cause; usually this happens for psychological reasons. There is usually no way to distinguish their experience from that due to tissue damage if we take the subjective report. If they regard their experience as pain and if they report it in the same ways as pain caused by tissue damage, it should be accepted as pain.

Medicine refers also to psychogenic pain or psychalgia as a form of chronic pain under the name of "persistent somatoform pain disorder" or "functional pain syndrome". Causes may be linked to stress, unexpressed emotional conflicts, psychosocial problems, or various mental disorders. Some specialists believe that psychogenic chronic pain exists as a protective distraction to keep dangerous repressed emotions such as anger or rage unconscious.

It remains controversial, however, that chronic pain might arise purely from emotional causes. Treatment may include psychotherapy, antidepressants, analgesics, and other remedies that are used for chronic pain in general.

Diffuse myelinoclastic sclerosis, sometimes referred to as Schilder's disease, is a very infrequent neurodegenerative disease that presents clinically as pseudotumoural demyelinating lesions, that make its diagnosis difficult. It usually begins in childhood, affecting children between 5 and 14 years old, but cases in adults are possible.

This disease is considered one of the borderline forms of multiple sclerosis because some authors consider them different diseases and others MS variants. Other diseases in this group are neuromyelitis optica (NMO), Balo concentric sclerosis and Marburg multiple sclerosis.

NPH may exhibit a classic triad of clinical findings (known as the Adams triad or Hakim's triad) of urinary incontinence, gait disturbance, and dementia (commonly referred to as "wet, wacky and wobbly" or "weird walking water").

- Gait disturbance is typically the initial and most prominent symptom of the triad and may be progressive, due to expansion of the ventricular system, particularly at the level of the lateral ventricles, leading to traction on the corticospinal tract motor fibers descending to the lumbosacral spinal cord. The gait disturbance can be classified as mild (cautious gait or difficulty with tandem gait), marked (evident difficulty walking or considerable unstable gait) or severe (unaided gait not possible) In the early stages, most often this gait disturbance occurs in the form of unsteadiness and impaired balance, especially when encountering stairs and curbs. Weakness and tiredness of the legs may also be part of the complaint, although examination discloses no paresis or ataxia. Often a mobility aid is used for added stability, once the patient has reached the mild to marked stage. Such aids may include a quad cane or wheeled walker. The patient's gait at the marked stage will often show a decrease in step height and foot-floor clearance, as well as a decrease in walking speed. This style is often referred to as a magnetic gait, in which the feet appear to be stuck to the walking surface, and is considered the characteristic gait disturbance of NPH. The gait may begin to mimic a Parkinsonian gait, with short shuffling steps and stooped, forward-leaning posture, but there is no rigidity or tremor. An increased tendency to fall backwards is also seen, and a broad-based gait may be employed by the patient in order to increase their base of support and thereby their stability. In the very late stages, the patient can progress from an inability to walk, to an inability to stand, sit, rise from a chair or turn over in bed; this advanced stage is referred to as "hydrocephalic astasia-abasia".

- Dementia is predominantly frontal lobe in nature and of the subcortical type of dementia. It presents in the form of abulia, forgetfulness, inertia, inattention, decreased speed of complex information procession (also described as a dullness in thinking and actions), and disturbed manipulation of acquired knowledge, which is reflective of the loss of integrity of the frontal lobes. Memory problems are usually a component of the overall problem and have been predominant in some cases, which can lead to the misdiagnosis of Alzheimer's disease. However, in NPH there may be an obvious discrepancy between (often severely) impaired recall and intact or much less impaired recognition. The dementia is thought to result from traction on frontal and limbic fibers that also run in the periventricular region.

- Urinary incontinence appears late in the illness, and is found to be of the spastic hyperreflexic, increased-urgency type associated with decreased inhibition of bladder contractions and detrusor instability. In the most severe cases, bladder hyperreflexia is associated with a lack of concern for micturition due to the severe frontal lobe cognitive impairment. This is also known as "frontal lobe incontinence", where the patient becomes indifferent to their recurrent urinary symptoms.

In voluntary urination, the bladder's normally relaxed detrusor muscle contracts to squeeze urine from the bladder.

One study, of 109 children diagnosed with giggle incontinence at Schneider Children's Hospital in New York, concluded that the cause of giggle incontinence is involuntary contraction of the detrusor muscle induced by laughter.

Because the complaint is difficult to reproduce under controlled conditions, its triggering mechanism is not clearly understood, but may be related to cataplexy, a sudden transient episode of loss of muscle tone often triggered by strong emotions.