Psychology: Perceptual Disturbances

Perceptual Disturbances

• Illusion: misinterpretation of an existing sensory stimulus
• Hallucination: sensory perception without an actual external stimulus
• Types of hallucinations:
  • Auditory: most common in schizophrenic patients
  • Visual: less common in schizophrenia, may accompany drug intoxication, drug and alcohol withdrawal, or delirium
  • Olfactory: usually an aura associated with epilepsy
  • Tactile: usually secondary to drug use or alcohol withdrawal

Formal Thought Disorders

• Thought process differs from thought content in that it does not describe what the person is thinking, but rather how the thoughts are formulated, organized, and expressed
• Normal thought process: typically described as linear, organized, and goal-directed
• Abnormal thought processes:
  • Circumstantiality: overinclusion of trivial or irrelevant details that impede the sense of getting to the point
  • Tangentiality: in response to a question, the patient gives a reply that is appropriate to the general topic without actually answering the question
  • Clang associations: thoughts are associated by the sound of words rather than by their meaning
  • Derailment (loose associations): a breakdown in both the logical connection between ideas and the overall sense of goal-directedness
  • Word salad: incoherent collection of words
  • Flight of ideas: a succession of multiple associations so that thoughts seem to move abruptly from idea to idea

DSM-5 Criteria for Psychosis

• Hallucinations and/or delusions
• Symptoms do not occur only during an episode of delirium
• Evidence from history, physical, or lab data to support a medication or substance-induced cause

Schizophrenia

• Characterized by disturbances in cognition, emotion, perception, thinking, and behavior
• Probably comprises a group of disorders along a spectrum with heterogeneous etiologies and is characterized by:
  • Disturbances in cognition, emotion, perception, thinking, and behavior
  • Structural and functional abnormalities visible in neuroimaging studies
  • Genetic component as seen in twin studies
• Classically, patients with schizophrenia are described as having:
  • Poor insight into the nature and the severity of their disorder
  • Lack of compliance with treatment
• The disorder is usually chronic, with a course encompassing:
  • Prodromal phase: decline in functioning that precedes the first psychotic episode
  • Active phase: perceptual disturbances, delusions, and disorganized thinking
  • Residual phase: occurs following an episode of active psychosis

Symptoms of Schizophrenia

• Thought broadcasting: the patient's thoughts escape into the outside world and are experienced by others
• Thought withdrawal: the patient's thoughts are being removed by an external force
• Thought insertion: the patient's thoughts are being inserted by an external force
• Running commentary: voices commenting on one's actions
• Thought echo: audible thoughts, voices speaking the patient's thoughts aloud
• Third-person auditory hallucinations: voices arguing, the patient hears two or more voices, talking to each other, in their head

Epidemiology

• Schizophrenia affects approximately 0.5-1% of people over their lifetime
• Men and women are equally affected, but have different presentations and outcomes:
  • Men tend to present in early to mid-20s, have more negative symptoms and poorer outcomes
  • Women present in late 20s
• Schizophrenia rarely presents before age 15 or after age 55
• Strong genetic predisposition:
  • 46% concordance rate among monozygotic twins
  • 40% risk of inheritance if both parents have schizophrenia
  • 12% risk if one first-degree relative is affected

Etiological Theories

• Genetic: genetic factors account for the majority of liability to schizophrenia, heritability estimates range from 60% to 80%
• Biologic:
  • Neurochemical abnormality hypotheses:
    • Dopaminergic overactivity
    • Glutaminergic hypoactivity
    • Serotonergic (5-HT) overactivity
    • Alpha-adrenergic overactivity
    • Gamma-aminobutyric acid hypoactivity
  • Neurodevelopmental hypothesis:
    • Excess of obstetric complications in those who develop the disorder

Prognosis

• Worse with poor premorbid adjustment, slow onset, early onset, predominance of psychotic symptoms, long course, and family history of schizophrenia
• Schizoaffective patients have a better prognosis than schizophrenic patients and a worse prognosis than mood disorder patients

Treatment

• Hospitalization (if necessary) and supportive psychotherapy
• Medical therapy: antipsychotics, mood stabilizers, antidepressants, or electroconvulsive therapy (ECT) may be indicated for treatment of mood symptoms

Brief Psychotic Disorder

• Diagnosis and DSM-5 Criteria:
  • Patient with psychotic symptoms as in schizophrenia, but the symptoms last from 1 day to 1 month, and there must be an eventual full return to premorbid level of functioning
  • Symptoms must not be due to the effects of a substance (drug or medication) or another medical condition
• Prognosis:
  • By definition, the course of the disorder is less than 1 month
  • Recovery is up to 80% with treatment

Delusional Disorder

• Disorder in which the primary or sole manifestation is a non-bizarre delusion that is fixed and unshakable
• Delusions are usually about situations that can occur and are possible in real life
• Delusional disorder occurs more often in middle-aged or older patients (after age 40)
• Delusions last at least 1 month and are well-systematized and non-bizarre as opposed to fragmented and bizarre
• The patient's emotional response to the delusional system is congruent with and appropriate to the content of the delusion
• The personality remains intact or deteriorates minimally