I am presenting a lot of data, I know. I could not find a single Internet reference, so I had to piece all articles together. It would be easier to use a textbook on psychology.
To sum everything up: 1) people diagnosed with schizophrenia who have persistent hallucinations also have self-recognition deficit. Lack of proper self-recognition indicates mental retardation. 2) Use of drugs could cause paranoid schizophrenia characterized by persistent hallucinations and low IQ.
Paranoid Schizophrenia Risk Factors:
1) Family History
2) Maternal Illness During Pregnancy.
3) Maternal Nutritional Deficiency During Pregnancy.
4) Medical Problems During Pregnancy and Birth.
5) A child born to an older father
6) Childhood abuse and other trauma .
7) Low IQ.

Stressful Life Circumstances.
9) Use of drugs
Difference between schizophrenia and paranoid schizophrenia
Schizophrenia is a mental disorder that makes it difficult to tell the difference between real and unreal experiences, to think logically, to have normal emotional responses, and to behave normally in social situations. Paranoid schizophrenia is one of several types of schizophrenia, paranoid schizophrenia is a serious, lifelong condition that can lead to many complications, including suicidal behavior.
Symptoms
* Auditory hallucinations, such as hearing voices
* Delusions, such as believing a co-worker wants to poison you
* Anxiety
Anger
* Emotional distance
* Violence
* Argumentativeness
* Self-important or condescending manner
www.medic4help.com -----------------------------------------------
Read more:
http://wiki.answers.com/Q/Can_an_adult_ ... z1TXUt2RRhQ. Can an adult who is diagnosed with paranoid schizophrenia also be retarded?
A. Yeah they can, it's called "Propfschizophrenie". They used to think that antipsychotics were causing the intellectual disability (which is what you should call it instead of retardation) but later research found out that it only happens because they're co-occuring.
--------------------------------
'Pfropfschizophrenie' revisited. Schizophrenia in people with mild learning disability.
Doody GA, Johnstone EC, Sanderson TL, Owens DG, Muir WJ.
Abstract
BACKGROUND:
It is reported that people with mild learning disability have a higher point prevalence of schizophrenia than the normal population, the reasons for which are unclear.
METHOD:
Thirty-nine subjects with mild learning disability and schizophrenia, 34 control subjects with schizophrenia and 28 control subjects with mild learning disability were seen. Interviews with relatives and carers were also conducted. Assessments were made of clinical variables, psychopathology, neurological 'soft' signs, IQ, memory and family history. Blood was taken for karyotypic analysis from comorbid subjects.
RESULTS:
The comorbid group had more negative symptoms, episodic memory deficits, soft neurological signs, epilepsy and receive more community supports than control subjects with schizophrenia. Comorbid subjects had a tendency to belong to multiply affected families and show high rates of chromosomal variants on routine karyotypic testing.
CONCLUSIONS:
Future work on the generality of schizophrenia should include people with premorbid learning disability, as a discrete subtype from whom valuable genetic aetiological clues may be obtained.
--------------------------
Premorbid IQ varies across different definitions of schizophrenia
ANNICK URFER PARNAS,1 LENNART JANSSON,1 PETER HANDEST,1 JAN NIELSEN,2 DITTE SÆBYE,3,4 and JOSEF PARNAS1
“This study demonstrates that only certain diagnostic definitions of schizophrenia are associated with lower IQ. There is a higher premorbid IQ in the patients diagnosed by broad definitions, which pick up a higher number of persons with schizophrenia (ICD-8/9 and Flexible System- Wide). As a function of its lowest number of detected schizophrenia patients, the ICD-10 may be considered as the most restrictive system, favouring selection of more chronic patients with lower IQ.”
Self-recognition Deficits in Schizophrenia Patients With Auditory Hallucinations: A Meta-analysis of the Literature
Todd Woodward, Paul Allen.
“We found significantly reduced self-recognition performance in schizophrenia patients, which was more pronounced in patients with auditory hallucinations compared with patients without. In patients with hallucinations, this pattern of performance was specific to self-recognition processes and not to the recognition of new external information. A striking finding was the homogeneity in results across studies regardless of the action modality, timing delay, and design used to measure self-recognition. In summary, this review of studies from the last 30 years substantiates the view that self-recognition is impaired in patients with schizophrenia and particularly those with auditory hallucinations. This suggests an association, perhaps a causal one, between such deficit and hallucinatory experiences in schizophrenia“
Self-Recognition Ability in Mentally Retarded Adolescents
Journal article by Jerry L. Fryrear, Thomas L. Kodera, M. J. Kennedy; Journal of Psychology, Vol. 108, 1981
“Self-recognition abilities of 30 mentally retarded adolescents were mea-
sured using an optical system and a psychophysical scaling procedure that
results in a recognition threshold. Compared with college freshmen, the
experimental group had significantly higher thresholds (p = .00003). Males
were better than females at recognizing full-face self-images (p = .0238).
Results were discussed in terms of the retarded adolescents' greater depen-
dency on specific visual cues. The method is discussed as an advance over
previous self-recognition methods because of accuracy and the capability of
measuring a range of self-recognition abilities“.
--------------------------------
Did Hubbard hallucinate? If he was going OT, he, definitely, did -- there is ample evidence that OTs hallucinate. If he invented Xenu stories and other things without experiencing that stuff, then he did not hallucinate.
The above text shows that the use of drugs is a risk factor as far as paranoid schizophrenia is concerned. There is plenty of stories on the Internet describing Hubbard’s use of drugs since early adulthood.
A reasonable assumption in Hubbard’s case would be that his use of drugs caused his paranoid schizophrenia, which is characterized by low IQ.
-----------------------------
My cousin and the Swedish psychiatrist did not meet Hubbard in person, they provided posthumous diagnoses of his mental state. Their diagnoses support each other, but there is no substitute for a direct measurement of Hubbard’s IQ.