Onset and Initial Presentation of Schizophrenia Spectrum Disorders

Onset and Initial Presentation of Schizophrenia Spectrum Disorders

Epidemiology of Schizophrenia Spectrum Disorders

  • Epidemiology: The method used to find the causes of health outcomes and diseases in populations.

    • Prevalence: Refers to the proportion of persons who have a condition at a particular time.

    • Important for understanding the burden of a disease on society at any given moment.

    • Incidence: Refers to the proportion or rate of persons who develop a condition during a specified time.

    • Important for understanding changes in the expression of disease in individuals.

Prevalence of Schizophrenia Spectrum Disorders

  • Obtaining precise prevalence estimates is challenging.

    • Factors affecting this include:

    • Complexity of diagnosis.

    • Overlap with affective disorders.

    • Variation in diagnostic methods.

  • Best Estimates:

    • Prevalence in the U.S. ranges from 0.25% to 0.64%.

    • International prevalence ranges from 0.33% to 0.75%.

    • There is an observed increase in prevalence over time.

Prevalence by Age and Sex

  • Incidence is higher in males compared to females, with a ratio of 1.4:1.

    • Males tend to be diagnosed earlier than females, resulting in a higher ratio in younger age groups.

  • Mortality rates in females are lower, altering the male-to-female ratio over time, with males being higher until middle age.

Global Prevalence per 100,000 People

  • New estimates (Solmi et al., 2023) indicate that the raw prevalence of schizophrenia increased from 14.2 million to 23.6 million people between 1990 and 2019.

  • Increases have been consistent across both males and females.

  • Variations in prevalence by region.

    • Factors contributing to the increase include:

    • Rise in incidence.

    • Increasing life expectancy.

    • Decreasing stigma surrounding mental health in some areas.

Incidence of Schizophrenia Spectrum Disorders

  • Like prevalence, incidence calculation faces challenges.

    • Traditionally believed to be constant geographically and temporally, though this has proven incorrect.

  • Geographically: The incidence ranges from 7.7 to 43.0 per 100,000, depending on the region studied.

  • Temporally: Global incidence increased from 941,000 to 1.3 million from 1990 to 2019 (Solmi et al., 2023).

Incidence by Sex and Age

  • Early diagnosis is more common in males; females tend to be diagnosed later.

  • Modal Age of Onset:

    • Males: Approximately 21 years.

    • Females: Approximately 26 years.

  • Females show a second peak around menopause.

    • Earlier onset in males linked to higher susceptibility of neurodevelopmental disorders.

    • Later peak in females could be related to the loss of antidopaminergic effects of estrogens.

  • Incidence declines with age in both sexes.

Why is Incidence Increasing?

  • Cannabis Use:

    • More potent cannabis and increased usage observed over the last two decades may correlate with rising schizophrenia incidence (Hjorthøj et al., 2021).

    • Cannabis use disorder correlates strongly with general population usage.

Population-Attributable Risk Fraction (PARF)

  • PARF estimates the cases of schizophrenia that might have been prevented if cannabis use disorder was eliminated.

  • Developed insights from Hjorthøj et al.'s study in Denmark.

Factors Associated with Increased Incidence

  • Urban Living:

    • Higher population density and poverty rates in urban areas are risk factors for schizophrenia (Kirkbride et al., 2017).

    • Immigrant populations in urban settings exhibit increased risk (Eger et al., 2022).

    • Environmental factors: Poor air quality, lower sun exposure, daily stressors associated with schizophrenia risk.

Burden of Schizophrenia

  • Associated with significant health, social, and economic issues despite its relatively low prevalence.

  • Approximately 50% of individuals have comorbid psychiatric diagnoses.

  • Ranked among the top 15 causes of disability worldwide.

  • Increased risk of premature death due to co-occurring medical conditions (e.g., heart disease, diabetes).

    • Suicide rate: 4.9% in individuals with schizophrenia vs. 1.4% in the general population.

    • Average potential life lost: 28.5 years for individuals with schizophrenia in the U.S.

Global Disability-Adjusted Life Years (DALYs) per 100,000

  • DALY: Measures the total years lost due to specific causes and risk factors.

  • One DALY equals one lost year of healthy life, providing insights at various levels (country, region, global).

Childhood Onset Schizophrenia (COS)

  • Rare condition in individuals 12 years old or younger.

    • Approximately 30-50% of kids with atypical psychotic symptoms misdiagnosed as COS.

    • Over 90% of referrals for COS receive alternate diagnoses; general acceptance of incidence < 0.04%.

  • Characteristics of children with COS:

    • Significant premorbid disturbances (67% affected in social, motor, and language areas).

    • High comorbidity with mood disorders, anxiety disorders, and Autism Spectrum Disorders (27% prior to onset of psychosis).

Late Onset Schizophrenia (LOS)

  • Defined as onset after age 45, with a prevalence of ~0.6%.

    • Very Late Onset (after age 60): Prevalence 0.1-0.5%.

  • Commonly seen in females around menopause and linked with:

    • High levels of occupational functioning.

    • Higher marital status.

    • Presence of severe paranoid delusions and multifaceted hallucinations (visual, tactile, olfactory).

Risk Factors for Late-Onset Schizophrenia

  • Negative life events.

  • History of prior psychotic symptoms.

  • Poor social networks.

  • Cognitive impairment and functional limitations.

Average Age of Onset

  • Late adolescence to early adulthood:

    • Males: Ages 18 to 25.

    • Females: Ages 25 to 35.

  • This is a critical developmental stage.

Adolescence: The Age of Opportunity

  • Adolescent brains have enhanced plasticity, allowing adaptation to experiences more readily.

    • Plasticity defined as the brain's ability to change.

Pre- to Post-Adolescent Changes

  • Major maturation changes in brain regions, especially cortical areas.

    • Synaptic Pruning: The removal of less-utilized synapses, reflected in cortex thinning.

    • Myelination: Development of axons leading to increased white matter.

Importance of Early Intervention

  • Goal of early identification is prevention:

    • Identify diseases early to mitigate full development or provide protection against severe outcomes.

  • Can schizophrenia spectrum disorders be detected early in their emergence?

The Psychosis Prodrome

  • Described as the first stage of schizophrenia, appearing before clear psychotic symptoms.

    • Characterized by behavioral and cognitive changes.

    • Only approximately 75% of individuals with schizophrenia may experience this prodromal stage.

Initial Presentation of Schizophrenia Spectrum Disorders

  • No typical presentation exists; common signs include social withdrawal and impaired functioning.

    • Onset may be:

    • Progressive: Over months or years.

    • Acute: Over days or weeks.

    • May have a history of psychiatric symptoms (anxiety, mood disturbances) or none.

    • Diagnosing schizophrenia spectrum disorders requires patience and time.

Initiation of Treatment

  • A high percentage of adolescents diagnosed (around 84% aged 15-29) are diagnosed in emergency departments.

  • Only about 19% diagnosed between 30-59 receive treatment during general medical visits.

  • Treatment initiations show significant variability.

Duration of Untreated Psychosis (DUP)

  • Defined as the duration from first psychotic symptom to first psychiatric hospitalization.

    • Average DUP ranges from 22 weeks to over 150 weeks.

  • Factors that contribute to lengthy DUP include:

    • Intrinsic: Symptom severity, patient attitudes.

    • Extrinsic: Access to care, insurance, culture.

Impact of Short vs. Long DUP

  • Longer DUP often correlates with more severe illness and poorer treatment outcomes:

    • Potential explanations:

    • Toxicity of psychosis.

    • Early insidious onset.

    • Recent studies suggest Lead Time Bias exists—longer DUP may not predict a worse illness trajectory.

Lead Time Bias

  • Extended DUP individuals may show greater negative psychosocial loss before hospitalization but greater dysfunction post-admission.

  • This topic remains debated within the field resulting in concern over overall messaging.

Next Topics

  • Historical Perspectives to be discussed in the next session.

  • Enjoy your Spring Break!