Multiple complex developmental disorder is a research category, proposed to involve several neurological and psychological symptoms where at least some symptoms are first noticed during early childhood and persist throughout life. It was originally suggested to be a subtype of autistic spectrum disorders (PDD) with co-morbid schizophrenia or another psychotic disorder, however there is some controversy that not everyone with MCDD meets criteria for both PDD and psychosis. The term multiplex developmental disorder was coined by Simon Baron-Cohen

Simon Baron-Cohen

Simon Baron-Cohen FBA is professor of Developmental Psychopathology in the Departments of Psychiatry and Experimental Psychology at the University of Cambridge in the United Kingdom. He is the Director of the University's Autism Research Centre, and a Fellow of Trinity College...

 in 1986.

Diagnostic criteria

The current diagnostic criteria for MCDD is a matter of debate due to it not being in the DSM-IV or ICD-10. Various websites contain various diagnostic criteria. At least three of the following categories should be present. Co-occurring clusters of symptoms must also not be better explained by being symptoms of another disorder such as experiencing random mood swings due to autism, cognitive difficulties due to schizophrenia, and so on. The exact diagnostic criteria for MCDD remains unclear but may be a useful diagnosis for people who do not fall into any specific category. It could also be argued that MCDD is a vague and unhelpful term for these patients.

Psychotic symptoms

Criteria is met for a psychotic disorder.

Some symptoms may include:

1. Delusions, such as thought insertion
   Thought insertion
   Thought insertion is the idea that another thinks through the mind of the patient. The patient may sometimes be unable to distinguish between their own thoughts and those inserted into their minds. A patient who is diagnosed with this disorder is found to be convinced of their beliefs and...
   
   , paranoid preoccupations, fantasies of personal omnipotence, over engagement with fantasy figures, grandiose fantasies of special powers, referential ideation, and confusion between fantasy and real life.
2. Hallucinations and/or unusual perceptual experiences.
3. Negative symptoms (anhedonia
   Anhedonia
   In psychology and psychiatry, anhedonia is defined as the inability to experience pleasure from activities usually found enjoyable, e.g. hobbies, exercise, social interaction or sexual activity....
   
   , affective flattening, alogia
   Alogia
   In psychology, alogia , or poverty of speech, is a general lack of additional, unprompted content seen in normal speech. As a symptom, it is commonly seen in patients suffering from schizophrenia, and is considered as a negative symptom...
   
   , avolition
   Avolition
   Avolition is a psychological state characterized by general lack of drive, or motivation to pursue meaningful goals. A person may show little participation in work or have little interest in socializing. They may sit still for long periods of time...
   
   )
4. Disorganized behavior and/or speech such as thought disorder, easy confusability, inappropriate emotions/facial expressions, uncontrollable laughter, etc.
5. Catatonic behavior
   Catatonia
   Catatonia is a state of neurogenic motor immobility, and behavioral abnormality manifested by stupor. It was first described in 1874: Die Katatonie oder das Spannungsirresein ....
   
   .

Neurotic and behavioral symptoms

These symptoms are not due to situations such as, person is depressed because of difficulty making friends. It is normal to experience dysfunctional emotions and behaviors at times.
Criteria is met for a neurotic or personality disorder, preferably at least two.

Some symptoms may include:

1. Depression.
2. Mania.
3. Anxiety.
4. Anger.
5. Dissociative symptoms such as depersonalization, derealization, deja vu, etc.
6. Emotional instability.
7. Psychopathic behavior.
8. Narcissism
   Narcissism
   Narcissism is a term with a wide range of meanings, depending on whether it is used to describe a central concept of psychoanalytic theory, a mental illness, a social or cultural problem, or simply a personality trait...
   
   .
9. Paranoia.
10. Obsessive-compulsive behavior.

Autistic symptoms

Criteria is met for an autistic spectrum disorder.

Some symptoms may include:

1. Difficulty with social skills
   Social skills
   A social skill is any skill facilitating interaction and communication with others. Social rules and relations are created, communicated, and changed in verbal and nonverbal ways. The process of learning such skills is called socialization...
   
   .
2. Repetitive behaviour and patterns.
3. Sensory integration disorder. (Poor motor skills, poor auditory processing, poor depth perception
   Depth perception
   Depth perception is the visual ability to perceive the world in three dimensions and the distance of an object. Depth sensation is the ability to move accurately, or to respond consistently, based on the distances of objects in an environment....
   
   , etc.)
4. Alexithymia
   Alexithymia
   Alexithymia from the Ancient Greek words λέξις and θυμός modified by an alpha-privative—literally "without words for emotions"—is a term coined by psychotherapist Peter Sifneos in 1973 to describe a state of deficiency in understanding, processing, or describing...
   
   . (Difficulty expressing self, difficulty understanding emotions, literal concrete thinking, etc.)
5. lack of eye contact.
6. Intense, singular interests.
7. Low interest in dress up games during childhood.

Neurological symptoms

Because these are frequently found in cases of autistic disorders, criteria should be met for multiple neurological disorders, or cause severe symptoms.

Some examples include:

1. Learning difficulties symptoms such as dyslexia
   Dyslexia
   Dyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid...
   
   , dysgraphia
   Dysgraphia
   Dysgraphia is a deficiency in the ability to write primarily in terms of handwriting, but also in terms of coherence. It occurs regardless of the ability to read and is not due to intellectual impairment...
   
   , dyscalcula, NVLD, slow learning, poor memory, etc.
2. AD/HD symptoms such as poor concentration, poor decision making, poor judgement, impulsiveness, difficulty sitting still, etc.
3. Synesthesia
   Synesthesia
   Synesthesia , from the ancient Greek , "together," and , "sensation," is a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway...
   
   .
4. Neurological sleep disorders such as narcolepsy, insomnia, circadian rhythm disorder, etc.
5. Conditions affecting perceptions and/or cognition, such as agnosia, aphasia, etc.
6. Tourette's or Tic disorder.
7. Epilepsy or Seizure disorder.
8. Parkinsonian features such as tremors, stiff movements, etc.
9. Mental retardation.

MCDD savants

Some people with MCDD who also have savant abilities

Savant

Savant may refer to:* An expert or wise person* Savant syndrome* Marilyn vos Savant* Savant publications* Doug SavantIn popular culture:* Characters in the Noble Warriors Trilogy...

 associated with different symptoms may have some advantages despite their disability because their unusual range of symptoms allows them to have a lot of creativity and an alternative thought processes. Several people famous in history have been thought to have features of autism

Autism

Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...

 and psychosis

Psychosis

Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...

 but were at the time, undiagnosable.

Causes

Multiple complex developmental disorder is likely to be caused by a number of different various genetic factors. Each individual with MCDD is unique from one another and displays different symptoms. Various neuropsychological disorders can also be found in family members of people with MCDD.

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