Pathological laughter: characteristics and disorders associated with this symptom.

A summary about the characteristics of pathological laughter, a symptom to be taken into account.

Laughing is synonymous with happiness, joy and good humor. We should all incorporate the healthy exercise of laughing into our lives, as it has many mental and physical benefits.

However, sometimes, laughing for no reason and without it being appropriate can be an indicator that something is wrong. This is known as pathological laughter, a symptom associated with psychopathology and neurological diseases. in which we are going to deepen next.

What is pathological laughter?

Laughter is a fundamental aspect of our lives. It is the "symptom" that reflects a state of joy, being related to very healthy effects for our mental and physical health. Sometimes, however, laughter can actually be a pathological symptom, indicating that something is wrong at the brain level.

Normal laughter may be triggered by a reflex action, such as tickling. In this case, tickling causes laughter to be triggered by reflex mechanisms. It can also be triggered by witnessing a funny event, such as hearing a joke or seeing someone slip on a banana skin. How two such disparate situations can provoke the same response is still an unknown.

However, as we have already mentioned, sometimes laughter is a sign that something is wrong. Pathological laughter is considered to be that which appears without reason, without being proportional to the emotional stimulus that has supposedly triggered it, unrestrained, uncontrolled or which appears without any apparent relation to the stimulus.

With what disorders is it related?

As we have already mentioned, laughter, in general, is a symptom of health, happiness and good humor. However, it is also a sign of a health problem, either of medical origin or of a psychopathological type, being much more stereotyped compared to normal laughter.

There are many disorders in which pathological laughter appears as a symptom. In most of them it appears as something uncontrollable, with incontinence and affective lability. Below we will see several groups of medical and psychological problems in which pathological laughter can be found.

1. Neurological diseases

Pathological laughter characterizes certain diseases of the central nervous system, such as tumors, multiple sclerosis, cerebral vascular diseases, dementia and cranioencephalic trauma, among other nervous disorders.

1.1. Bulbar and pseudobulbar palsy

In bulbar and pseudobulbar palsy there is a unilateral or bilateral lesion of the corticobulbar motor pathways, which is related to pathological laughter. Among the medical causes behind the appearance of these palsies we have arteriosclerosis, multiple cerebral infarction and multiple sclerosis.

In this case, laughter is characterized by its disproportion to the emotional stimulus that supposedly triggers it. In fact, it is often described as emotional incontinence and may simulate a state of affective lability.

Other symptoms of bulbar and pseudobulbar palsy include the inability to make voluntary movements, although reflex movements such as laughing, crying and sucking are possible.

Among the brain regions affected in this neurological condition are: the internal capsule, the substantia nigra, the cerebral peduncles and the caudal hypothalamus. There are also bilateral lesions of the pyramidal tract, with involvement of extrapyramidal fibers.

1.2. Gelastic epilepsy

Gelastic epilepsy is characterized by the presence of sudden, self-limited, paroxysmal-onset laughing seizures produced by abnormal cortical discharges. This type of epilepsy was described in 1957 and its incidence is very small, 0.32%.

Seizures are more frequent during the day, and are accompanied by hypotonia and diaphoresis (excessive sweating). These episodes last about 30 seconds and are usually followed by a phase of amnesia.

Seizures are more frequent in childhood, and are often associated with the presence of hypothalamic tumors, which in turn is associated with the onset of precocious puberty.

This type of epilepsy can begin in the first days of life, and its most common cause is usually tumors in the hypothalamus, called hypothalamic hamartomas, and more than half of those who suffer from it have intellectual problems.

Cerebral vascular disease

A cerebral vascular disease, such as a stroke, may cause pathological laughing or crying fits, generally due to damage to the vertebral or basilar arteries, partially occluding them.

A special case is the so-called ridenti stroke, in which there is prolonged laughter for hours or even weeks, followed by hemiplegia, stupor or dementia. In this case, the disease is due to active destruction of brain tissue due to extensive intracerebral hemorrhage, which gradually progresses.

2. Intoxications

Pathological laughter may be caused by intoxication or substance abuse. Some examples of substances that induce non-normal laughter are hallucinogens (cannabis and hashish), LSD, alcohol, nitrous oxide (called, in fact, "laughing gas"), inhalation of insecticides, benzodiazepinesnitrous oxide (called, in fact, "laughing gas"), inhalation of insecticides, benzodiazepines in low concentrations or application of local anesthetics. It can also be caused by an accumulation of copper in brain tissues, a symptom of Wilson's disease.

3. Mental disorders

Pathological laughter is a symptom of several psychological disorders, and can be found in the manic phases of bipolar disorder and also associated with drug addictions, as we have seen in the previous section. However, the most common pathological laughter associated with mental disorders is that which occurs in schizophrenia.

3.1. Schizophrenia

In the case of schizophrenia, laughter appears without any emotional meaning, in the form of unprovoked or inappropriate outbursts, in the form of uncontrolled outbursts. Patients do not know why they are laughing, and feel they are forced to laugh..

Laughter may also appear in response to auditory hallucinations. Occasionally, patients may quickly veer into crying. Laughter in schizophrenia has been seen as highly pathological.

3.2. Hysteria and other neuroses

Although hysteria is not currently a diagnosis within the DSM, this disorder has a long history, originally described by Sigmund Freud. He himself indicated that repressed anxiety in hysteria can give rise to a specific affective state, which is accompanied by motor manifestations such as laughter.

In the case of hysteria, the occurrence of pathological laughter has been associated with low socioeconomic status, anxiety, feelings of guilt and loss of identity. Even so, the contagious nature is not explained.

3.3. Narcolepsy

Narcolepsy manifests itself in the form of daytime hypersomnolence, causing the person to suddenly fall asleep when they should be awake. It is not known exactly what causes it, although it is known to have a hereditary component.

The person suffers excessive daytime sleepiness, hypnagogic hallucinations, cataplexy, insomnia and sleep paralysis.

The laughter caused by this disorder is the trigger for cataplexic attacks, which consist of an abrupt loss of Muscle tone without a decrease in the level of consciousness, at a time when the patient is fully awake.

4. Pediatric disorders and diseases

There are several mental disorders and diseases that have their origin in childhood in which pathological laughter can be identified:

Angelman syndrome

Angelman syndrome was described in 1965 and is also called "happy puppet" syndrome. ("happy puppet"). It is a multiple malformation syndrome, which affects patients of both sexes and different races.

At the genetic level it is similar to Prader Willi syndrome, although here the genetic causes can be established in four types: maternal deletion (15q11-q13), paternal uniparental disomy, imprinting defects and mutations in the UBE3A gene.

The main symptoms present in this syndrome are: severe mental retardation, especially in the area of language, frequent laughter and happy appearance. This laughter is a characteristic feature of the syndrome, accompanied by a Machiavellianly happy appearance. In addition, they rarely cry or even never cry.

In terms of somatic symptoms we can find microbrachycephaly, prognathism, tongue protrusion, dental malposition, occipital flattening, uncoordinated body movements, ataxia, coma crises and visual atrophy.

4.2. Autism Spectrum Disorders (ASD)

Autism Spectrum Disorders is the diagnostic label under which several developmental disorders that until before the DSM-5 were considered separate but related entities have been encompassed as an umbrella, such as classic autism and Asperger's syndrome.

Among the symptoms presented in ASD are: difficulties in relating and playing with other children, behaving as if deaf, great resistance to any learning, not being afraid of real dangers, resistance to changes in routine, indicating needs through gestures, pathological laughter and not being affectionate, among other symptoms.

ASD usually presents itself before the age of three yearsIt is quite probable that there is some kind of intellectual problem, an exception being Asperger's syndrome.

4.3. Rett syndrome

Rett syndrome is a problem that intellectual deficiency.. So far it has only been described in girls and has been related to a mutation of the gene encoding the transcription factor MeCP2, which can be proven in 95% of cases.

People diagnosed with this syndrome present autistic behavior and inability to walk, growth retardation, eye alterations and stereotyped hand movements, among other signs and symptoms. They present sudden nocturnal laughter in more than 80% of the cases.

Final reflection

Although laughter is something that should be present in our lives, for its therapeutic value and for being the materialization of happiness and joy, sometimes it is a sign of suffering from a problem. If we know someone, family member or friend, who has sudden fits of laughter without knowing why, it may be an indicator that they are suffering from a problem, it may be an indicator that they are suffering from a medical illness or a psychological disorder, and that they need to be evaluated and treated.and needs to be evaluated and treated.

The best way to prevent a pathological situation from getting worse is to identify it early, and pathological laughter can be a symptom that warns us that it is time to act.

Bibliographical references:

• De Gregorio, C., Martínez, B. (1998). Normal and pathological laughter. Historical background, neuroanatomical and physiological bases, differential diagnosis. Public Psychiatry. 10: 19-25.
• Mora, R., García, M. C. (2008). The therapeutic value of laughter in medicine. Med Clin; 131: 694-8.
• Lancheros, E. A., Tovar, J., Rojas, C. (2011). Laughter and health: therapeutic approaches. Med UNAB.14: 69-75.