IDD-MH Prescriber Guidelines

Schizophrenia and Other Psychotic Disorders

L. Jarrett Barnhill, MD, DFAPA, FAACAP

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Psychoses are brain disorders associated with significant impairments in perception, attention, memory, social–emotional processing, thought processes, social communication and a group of executive functions that underlie “reality testing.” Psychoses lie on a continuum that ranges from clearly defined physiological abnormalities (delirium, post-ictal states, traumatic brain injury etc.) to those associated with severe trauma and psychosocial stressors (PTSD, brief reactive psychosis). The level of functional impairment varies based on severity, duration of psychotic experiences, comprehensive systemic treatments, and psychosocial factors. Some disorders, like delirium and untreated schizophrenia, can contribute to a shortened life span as well as persistent deficits in cognitive, social, and occupational functioning.

Psychotic experiences without obvious psychopathology occur in nearly 4%1 of healthy children and adults. For other at-risk individuals, psychotic experiences become a risk factor for other nonpsychotic mental disorders. Psychotic experiences take on a different meaning for individuals affected by severe trauma or co-occurring psychiatric disorders such as mood and anxiety disorders. For example, the expression of psychotic experiences in major depressive disorder can include recurring auditory hallucinations and delusions of worthlessness. In this context, psychotic experiences may result in a more severe disorder (Depressive psychosis) that will require modifications in treatment.

Psychotic experiences have a different meaning for adolescents or young adults who are genetically at high-risk for schizophrenia. Recent studies suggest that these individuals are at increased risk for brief or attenuated psychotic experiences. The stakes are even higher for those at-risk young adults who display not only psychotic experiences but who are also struggling with increasing social isolation, academic decline, and disorganized thoughts.  Around 40%2 of those with psychotic experiences will progress to Schizophrenia Spectrum Disorders (SSDs). The rest may develop a variety of personality, internalizing disorders and chronic functional impairments.  

In this section, we define risk level in terms of polygenic risk scores (multiple genes with small effect size) combined with other genetic changes (copy number variants) discussed in the vignette of a young woman with Velo-Cardio-Facial Syndrome (VCFS). But even in the contexts of behavioral phenotypes like VCFS, gene-effects do not occur in isolation. All too often, multiple premorbid insults (trauma, TBI) combine with multiple gene-environmental interactions to produce severe mental illness. The presence of ID and ASD contribute to risk scores.

Schizophrenia Spectrum Disorders (SSDs)

The prevalence of Schizophrenia Spectrum Disorders (SSD) in people with IDD is unknown. Some years ago, the idea was proposed that negative symptoms and cognitive changes represented the core features of SSD as a neurodevelopmental psychotic disorder. Positive symptoms reflected a different neurophysiology and gene expression. The positive symptoms represented trans-diagnostic features that co-occurred in other major psychiatric disorders. SSDs are a complex subset of the psychotic disorders. Current DSM-53 and DM-ID-24 diagnostic criteria require the presence of positive symptoms (hallucinations, delusions, thought and behavioral disorganization, catatonia) and negative symptoms. Nevertheless, there is a wide range of variability in gene-expression underlying SSDs (genotype to phenotype uncertainties). For example, genomic scans reveal the presence of genes that influence the development of SSD, ASD, ID, epilepsy, ADHD, and specific learning disabilities. Those abnormalities that influence early brain organization (early brain structures, synaptic stability, and integrated networks of neurotransmitter activity) are likely to present among the spectrum of neurodevelopmental disorders. The risk for primary psychiatric disorders may include similar genes, but in general at-risk genes modulate their expression. As a rule, the insults that occur later during gestation impact later developing skills. These modulations seem active in a different set of neurodevelopmental disorders, and yet even these aberrations do not determine outcome. In short, genetic risk factors resemble setting events or risk factors that are subject to modifications by life experiences. This leaves room for both positive (resilience) and negative (trauma, TBI) life influences.                       

Unfortunately, many clinicians overlook the role of ID and ASD in altering predisposition, nature of precipitating factors, clinical presentation, symptomatic course, and treatment response of psychotic experiences.  Fortunately, most individuals with SSD and IDD respond to common treatment options. But what about those who do not?  This challenges us to explore the “uncertainties” of our knowledge base. For example, why do only 40% of very high-risk individuals go on to develop a full-blown SSD? Likewise, why do we find nearly 50% discordance rates among high-risk monozygotic twins?       

Dividing psychotic disorders and SSDs into primary and secondary subtypes can be helpful. The primary disorders represent the major psychiatric disorders in the DSM-53 and DM-ID-24.The secondary disorders represent phenocopies associated with the presence of acute or chronic medical/neurological disorders, and those associated with genetic, metabolic, neurodegenerative, traumatic brain injury, or substance use disorders. This dichotomy demonstrates that there are many pathways to psychotic disorders or SSDs.  For example, SSDs may have a different developmental trajectory (mosaic rather than linear progression) that moves from premorbid, prodromal, attenuated psychotic experiences, and full-syndrome schizophrenia. The developmental trajectory for secondary disorders may follow the course of a metabolic disorder or an improved level of seizure control. Primary and secondary disorders share in their vulnerability to gene-environmental interactions and systemic response to multiple psychosocial and ecological forces. They also represent final common pathways that suddenly grow more complicated when we add IDD/ASD to the mix.


Table 1. Spectrum of Psychotic Disorders

Core Features of Psychosis

Schizophrenia Spectrum Disorders

Psychosis Due to Other Medical Disorders

Borderline-Mild IDD

Severe-profound IDD


Core psychotic symptoms

Core psychotic symptoms

Core psychotic features

Core features present


Cognitive impairments

Visual and tactile hallucinations noted

SSD recognizable,

Complexity of delusions modified by cognitive limitations and life experiences 

Cognitive impairments may overshadow verbal expression of delusional states

Disorganized thinking or speaking

Negative symptoms

Brain disorders and prefrontal lesions associated with content specific delusions

High Polygenic Risk Score may link risk for ID and Schizophrenia

Limitations in language, but behavioral reactions, level of fear and avoidance may be clues

Abnormal motor behaviors- catatonia 

Specifiers and Differential diagnosis 

Dementias- e.g. Lewy Body- visual hallucinations, 

Later onset in Alzheimer’s disease

Confusion with EPS secondary to overuse and antipsychotic Rx for no psychotic disorders

Difficult to recognize, rule out APD side effects.

Differential diagnosis- R/O medical neurological disorders, delirium

Duration of psychotic features

Neurodegenerative disorders- psychosis may precede or occur during the trajectory

Milder forms of some neurodegenerative disorders may present with psychotic symptoms

R/O medical, neurological and metabolic disorders before finalizing psychotic dx. Prudent label as Psychotic Disorders due to Other Medical Conditions

Age of onset- relationship to autoimmune, inflammatory disorders

Functional impairment

Delirium- “acute brain failure”

Age of recognition may be delayed

Relationship to trauma

Age of recognition rather than onset, timeline relationship to major life events and traumatic experiences  

Pattern of onset- related to etiology, judgment call when medical and/or neurological disorders are present

early onset is related to worse prognosis

Onset linked to medical condition

Overshadowed by comorbid behavioral disturbances. For SSD, insidious onset with early negative symptoms may delay recognition based on positive symptoms

Positive symptoms related to medical/neurological disorders may overshadow negative symptoms  


icon of a magnifying glass over a documentCase Vignette

Part 1: Description of the person and background - MB is a 31-year old female with a ten year history of auditory hallucinations (pictures on the walls talking about her, shadows doing things to her, voices laughing and threatening her); occasional visual hallucinations (monsters dressed in black and white capes); increased social isolation and avoidance; and recurring thoughts of being watched by the police. On multiple occasions, she became extremely agitated for no obvious reason and struck wildly at unseen objects. Her working diagnosis by her local psychiatrist was treatment-resistant Psychosis Due to Other Medical Condition. She also had a poorly controlled mixed seizure disorder that required multiple anticonvulsants. There is no family history of primary psychiatric disorders.   

MB presents with a complex neurodevelopmental syndrome. Her differential diagnosis is a long one, but her symptoms suggest a metamorphosis over the past 5 years. She experienced a stepwise regression that created a major shift in her temperament, personality, social interests and social-communication abilities. She meets the diagnostic criteria for a psychotic disorder (suggestive of schizophrenia) based on clinical symptoms, duration of functional impairment, and episodic catatonic symptoms. There is nothing in her extensive work-up to suggest underlying metabolic or neurodegenerative disorders. There was no substantiated evidence of abuse, neglect, traumatic brain injury, or adverse drug reactions. At this point, there is documentation of failed trials of olanzapine, quetiapine, lucosamide and multiple mood stabilizers. Extensive interviews with family, group home staff, vocational staff and reviews of past psychological, medical and neurological history suggest “visual hallucinations in early childhood” that waxed and waned over time. Her “psychotic symptoms” markedly intensified during her early twenties.

Part 2: Current treatments - The examination reveals short stature, widely spaced eyes, expanded nasal bridge, and palmar creases. Her mental status examination was complicated by her catatonic muteness, and pre-occupation with the ceiling fan. She screamed about a monster riding on the blades mocking her. She had no EPS or dyskinesias, but occasional facial grimacing. Her labs show a low serum calcium and mild blood abnormalities, low Vitamin D3 and folic acid levels. Her genetic studies reveal a 22q 11.2-deletion syndrome- Velo-cardio-facial Syndrome (VCFS) without DiGeorge’s syndrome.

MB’s current treatments include risperidone 2 mg/d, Fluoxetine 10 mg/d and valproic acid 1500 mg BID (serum drug level of 105), but no psychotherapies or major ecological interventions. MB has a history of complex partial seizures, surgically corrected tetralogy of Fallot (congenital cardiac abnormality), submucosal cleft, moderate ID and previous diagnoses of ADHD, social anxiety and mild ASD.

Discussion - MB meets the criteria for treatment-resistant schizophrenia-like psychotic disorder, but lacks a positive family history for schizophrenia. The intriguing point in this case is the presence of 22q11.2 deletion syndrome. MB presents with core features of this deletion syndrome (large Copy Number Variant or CNV). The most interesting part of the story is the convoluted relationship between VCFS and a late-onset schizophrenia-like syndrome. This behavioral phenotype has generated a lot of excitement as a rare CNV that, although it makes up only a small part of the pool of schizophrenia CNV and single nucleotide polymorphisms, nearly 30% of individuals with VCFS develop SSD. There are genes involved that affect early brain development and regulation of neurotransmitter, inflammatory and mitochondrial activity. The treatment of VCFS in part depends on the length of the VCFS copy number variant (missing genes), the presence of co-occurring ID/ASD, ADHD and epilepsy (less common) and a range of psychosocial factors.

An overview of treatment options

Treatment relies upon assessment, differential diagnosis and a careful review of all treatment options. The selection of modified Cognitive Behavioral Therapies (CBT) depends on four factors:

  1. The individual’s position in the developmental trajectory of emerging psychosis
  2. The severity of psychotic symptoms (including comorbidities)
  3. The individual’s place in the treatment cycle (goal attainment)
  4. The reasonableness of individual preferences, availability of good therapists, and time availability

These factors suggest that modifications to CBT are helpful during premorbid, and prodromal (attenuated psychosis) periods and during maintenance treatment and medication reduction or elimination protocols. In addition to CBTs, family involvement in treatment for younger patients, social supports, community services, and employment opportunities are part of the process.

Pharmacotherapies are important but adjunctive to treatment. Since introduced in the 1950’s, antipsychotic drugs (APDs) have greatly improved SSD treatment options. There were many advances in APD technology based on a broader understanding of the pharmacokinetics, pharmacodynamics, and pharmacogenomics. These hypothesis-driven modifications still leave us without a cure and facing problems with residual negative symptoms, cognitive impairment, treatment resistance, polypharmacy and persistent, adverse drug reactions. At the same time, the use of APDs expanded into the realm of generalized drug treatment for a variety of nonpsychotic disorders. Nevertheless, we have learned a few things along the way.

  • The recovery rates are better for acute, first episode schizophrenia if the duration until treatment (DUP) is short, positive symptoms are present, and a rapid response to antipsychotic treatments occurs (improvement by six weeks).
  • This calculus changes when the onset is insidious, there is a long DUP of psychotic symptoms before beginning adequate treatment, compliance issues, significant EPS without improvement, negative symptoms dominate, and there are comorbid psychiatric, personality and substance use disorders.
  • The definition of treatment resistance is two or three treatment failures. Some treatment failures are due to poor medication adherenace generated by weight gain, Type 2 Diabetes, and cardiovascular side effects.
  • In addition to inconsistent follow-through with medications, treatment resistance is abetted by undertreated comorbid mood disorders (and OCD), unrecognized EPS (including akathisia), high dosing schedules that can mimic negative symptoms, and substance use.
  • The use of appropriate doses of long-acting injectable APDs can reduce concerns related to missed pills.
  • Diet and exercise education and programs, access to enjoyable wellness activities, primary care and occasionally metformin can be very helpful in reducing health care risks associated with APD treatment.
  • We are under-utilizing Clozapine but still need to remain vigilant to ongoing research findings about cardiovascular toxicity (myopathy), weight gain, GI complaints, hematological/stem cell suppression, and adverse effects on some forms of epilepsy.
  • All APDs are best initiated at low doses. Go slow, and keep in mind drug-drug interactions during its use. Maintain a keen eye on drug-drug interactions (managing polypharmacy), and the disruptive effects of EPS on measures of treatment response.
  • Application of nonpharmaceutical supports, variants of CBT, and well-structured but flexible dose reduction schedules are helpful. The decisions about which drugs to begin with, determining reductions in small decrements, close follow-up, and enhanced recognition of the difference between clinical relapse and extinction spurts need to be made carefully and not in isolation. Clinicians should expect variants of tardive dyskinesia and “withdrawal symptoms” and not panic with “knee jerk” re-instatement of antipsychotics.
  • Lastly, there are alternatives to polypharmacy that underscore the weakness in the dopamine hypothesis. Positive and negative symptoms, as well as cognitive symptoms may involve different neuronal networks and nodal-point neuropharmacologies. For example, treatment failure with dopamine/5-HTa antagonists force us to consider other factors. Recent treatment ideas involve networks associated with GABA, glycine, glutamine, nicotinic receptors, numerous peptide and hormonal neuromodulators, probiotics/omega-3 fatty acids, NAC and other novel interventions, focus on cognitive enhancement and transcranial magnetic stimulation.


The development of treatments for SSD/psychoses in people with IDD is still a work in progress. This section touched on many factors and workable solutions and includes evidence that the first- and second-generation antipsychotics work better for managing acute positive symptoms or assisting in maintenance treatment protocols. However, these same drugs are less helpful for chronic SSD with high levels of negative symptoms and cognitive impairments.

McGrath et. al.5 described the spectrum of “psychotic experiences” in terms of severity factors- mood-congruent hallucnations and delusions in psychotic depressive disorder. These observations segue into the use of APDs to alleviate the “psychotic experiences” in patients who failed to respond to antidepressant regimens. ECT and other biological therapies may be more effective for psychotic mood disorders than negative symptoms in chronic SSD. These observations may also point us towards other trans-diagnostic treatment approaches for psychotic symptoms in ASD, anxiety disorders and PTSD.

Given all of the information currently available, it may be the case that clinicians need to rethink psychotic disorders in individuals with ID and ASD. The conceptual model of “psychotic experiences” is a better fit for many people with ID who present with psychotic experiences but do not meet the criteria for a specific underlying psychiatric or neurological disorder. This approach might help us avoid labeling individuals with a psychotic disorder or schizophrenia, while supporting the idea that many of our current APD treatments can reduce psychotic experiences but be less effective in reducing the intense distress and suffering that require major ecological therapies.


1 Moreno-Küstner B, Martín C, Pastor L. Prevalence of psychotic disorders and its association with methodological issues. A systematic review and meta-analyses. PLoS One. 2018;13(4):e0195687.

2 Renard, SB, Rafaele JC, Huntjens, Lysaker, PH, et al. Unique and overlapping symptoms in schizophrenia spectrum and dissociative disorders in relation to models of psychopathology: A systematic review. Schizophr Bull. 2017; 43(1): 108–121.

3American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Washington, DC: American Psychiatric Association, 2013.

4 Fletcher RJ, Barnhill J, Cooper S-A (Eds). Diagnostic Manual-Intellectual Disability 2: A Textbook of Diagnosis of Mental Disorders in Persons with Intellectual Disability. Kingston, NY: NADD Press; 2017.

5 McGrath JJ, Saha S, Al-Harmzawi A, Andrade L, Benjet C, et al. The bidirectional associations between psychotic experiences and DS-IV diagnosis. Am J Psychiatry. 2016; 173(10):997-1006.



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