0_Wizard
My sister was diagnosed with Obsessive-compulsive disorder always needing to perform rituals. Are you familiar with OCD?
Obsessive–compulsive disorder (OCD) is a mental disorder where people feel the need to check things repeatedly, perform certain routines repeatedly (called "rituals"), or have certain thoughts repeatedly.
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Obsessive–compulsive disorder
chosen_topic_0_Obsessive–compulsive_disorder
Obsessive–compulsive disorder
Obsessive–compulsive disorder (OCD) is a mental disorder where people feel the need to check things repeatedly, perform certain routines repeatedly (called "rituals"), or have certain thoughts repeatedly. People are unable to control either the thoughts or the activities for more than a short period of time. Common activities include hand washing, counting of things, and checking to see if a door is locked. Some may have difficulty throwing things out. These activities occur to such a degree that the person's daily life is negatively affected. Often they take up more than an hour a day. Most adults realize that the behaviors do not make sense.
Delayed- Maturation Theory of Obsessive Compulsive Disorder
The Delayed-Maturation Theory of Obsessive Compulsive Disorder  suggests that Obsessive Compulsive Disorder (OCD) can be caused by delayed maturation of the frontal striatal circuitry or parts of the brain that make up the frontal cortex, striatum, or integrating circuits. Some researchers suspect that variations in the volume of specific brain structures can be observed in children that have OCD (Lambert, K.G; Kinsley, C.H., 2011). It has not been determined if delayed-maturation of this frontal circuitry contributes to the development of OCD or if OCD is the ailment that inhibits normal growth of structures in the frontal striatal, frontal cortex, or striatum.
Animal psychopathology
Animal psychopathology is the study of mental or behavioral disorders in animals. Historically, there has been an anthropocentric tendency to emphasize the study of animal psychopathologies as models for human mental illnesses. But animal psychopathologies can, from an evolutionary point of view, be more properly regarded as non-adaptive behaviors due to some sort of a cognitive disability, emotional impairment or distress. This article provides a non-exhaustive list of animal psychopathologies. Animals in the wild appear to be relatively free from eating disorders although their body composition fluctuates depending on seasonal and reproductive cycles.
Compulsive hoarding
Compulsive hoarding, also known as hoarding disorder, is a pattern of behavior that is characterized by excessive acquisition and an inability or unwillingness to discard large quantities of objects that cover the living areas of the home and cause significant distress or impairment. Compulsive hoarding behavior has been associated with health risks, impaired functioning, economic burden, and adverse effects on friends and family members. When clinically significant enough to impair functioning, hoarding can prevent typical uses of space, enough so that it can limit activities such as cooking, cleaning, moving through the house, and sleeping.
Obsessive–compulsive personality disorder
Obsessive–compulsive personality disorder (OCPD) is a personality disorder characterized by a general pattern of concern with orderliness, perfectionism, excessive attention to details, mental and interpersonal control, and a need for control over one's environment, at the expense of flexibility, openness to experience, and efficiency. Workaholism and miserliness are also seen often in those with this personality disorder. Persons affected with this disorder may find it hard to relax, always feeling that time is running out for their activities, and that more effort is needed to achieve their goals.
Tourette syndrome
Tourette syndrome (TS or simply Tourette's) is a common neuropsychiatric disorder with onset in childhood, characterized by multiple motor tics and at least one vocal (phonic) tic. These tics characteristically wax and wane, can be suppressed temporarily, and are typically preceded by an unwanted urge or sensation in the affected muscles. Some common tics are eye blinking, coughing, throat clearing, sniffing, and facial movements. Tourette's does not adversely affect intelligence or life expectancy. Tourette's is defined as part of a spectrum of tic disorders, which includes provisional, transient and persistent (chronic) tics.
Cause of obsessive-compulsive disorder
The cause of obsessive-compulsive disorder is concerned with identifying the biological risk factors involved in the expression of obsessive-compulsive disorder (OCD) symptomology. The leading hypotheses propose the involvement of the orbitofrontal cortex, basal ganglia, and/or the limbic system, with discoveries being made in the fields of neuroanatomy, neurochemistry, neuroimmunology, neurogenetics, and neuroethology. Although there has been substantial debate regarding the assessment of OCD, current research has gravitated toward structural and functional neuroimaging. These technological innovations have provided a better understanding of the neuroanatomical risk factors of OCD.
1_Apprentice
I do not have a lot of knowledge about it.  I frequently read that more and more children are being diagnosed with it.