Sex Differences in Health & Disease

SEX DIFFERENCES IN HEALTH & DISEASE

  • Lecturer: Grace Schamber

Question of the Day

  • What is a “place cell”?

    • A specific type of neuron found in the hippocampus that becomes activated when an animal is in, or is thinking about, a particular location in its environment.

  • Memory Associated:

    • Spatial memory, as it relates to navigation and understanding spatial environments.

Learning Objectives

  • Be able to:

    • Describe Differences in Sex:

    • Genetic, gonadal, and anatomical/phenotypic sex

    • Outline Sexual Differentiation Steps:

    • From the SRY gene to perinatal actions of sex hormones

    • Intersex Conditions:

    • Identify two intersex conditions and their mechanisms

    • Types of Sex Differences (Becker & Chartoff):

    • List and recognize an example for each type

    • Dual Function Hypothesis (De Vries):

    • Understand and provide an example

Relevant Reading

  • Textbook Chapter:

    • Chapter 12:

    • Learning Objectives: 12.1.3, 12.2.1-12.2.3, 12.5, 12.6

  • Review Articles on D2L:

    • Becker & Chartoff, 2019 (specific sections)

    • De Vries, 2004

    • Shansky, 2019 (optional)

Table of Clinical Entities with Sex and Gender Differences

  • Cardiology: Myocardial infarction (275)

  • Rheumatology/Immunology: Lupus erythematosus (414)

  • Pneumology: Asthma (140)

  • Nephrology: Renal failure (27)

  • Gastroenterology: Hepatitis B (22)

  • Neurology: Multiple sclerosis (65)

  • Endocrinology: Diabetes mellitus (447)

  • Oncology: Lung cancer (116)

  • Haematology: Anemia (44)

  • Hypertension (various sources):

    • Heart failure (153), hypertensive disorders, etc.

  • Statistics Reference: NCBI link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3388783/

Sex Differences in Brain Disease & Mental Illness

  • Female > Male:

    • PTSD

    • Depression

    • Anxiety

    • Alzheimer's & dementias

  • Male > Female:

    • Autism

    • Schizophrenia

    • Substance Abuse

    • Antisocial Personality Disorder

    • Note: Aspects of substance use disorders are more pronounced in females (Becker & Chartoff, 2019).

Sexual Differentiation

  • Overview:

    • Genetic sex, gonadal sex, morphological sex (including genitals), physical sex characteristics, hormonal processes, behavior, and brain development.

    • Key Point:

    • Variation is common; sex does not equate to gender.

Sex Determination in Mammals

  • Genetic Sex:

    • Male (XY Chromosomes) vs. Female (XX Chromosomes)

    • SRY Gene:

    • Determines male differentiation, suppresses female gonads.

    • Functions as a transcription factor activating pro-male differentiation.

  • Process:

    • Activation of testes leads to male phenotype; absence results in female structures.

Hormonal Processes in Sexual Differentiation

  • Sex Steroid Class and Synthesis:

    • All derived from cholesterol:

    • Progestins: Progesterone

    • Androgens: Testosterone (T) and Dihydrotestosterone (DHT)

    • Estrogens: Estradiol, Estriol (during pregnancy), Estrone (post-menopause)

Phenotypic Sex Determination

  • Influence of Hormones:

    • AMH and testosterone from testes influence internal structures.

    • In absence of these hormones, typical female structures develop.

Organizational vs. Activational Effects of Sex Hormones

  • Organizational Effects:

    • Permanent changes in brain structure due to hormone exposure during critical periods.

  • Activational Effects:

    • Hormonal influences that may change behavior or function during adulthood.

Types of Sex Differences (Becker & Chartoff Review)

  • Qualitative Differences:

    • E.g., behaviors such as mounting in males vs. lordosis in females.

  • Quantitative Differences:

    • E.g., differences in threat reactivity between sexes.

  • Population Differences:

    • E.g., variance in fat distribution patterns.

  • Convergent Differences:

    • E.g., similar maze-solving abilities with differing neural strategies.

Implications of Excluding Female Subjects in Research

  • Historical Context:

    • Relationship of gender biases in clinical studies; FDA restricted female participation historically.

    • NIH legislation aimed at increasing representation in clinical studies post-1993.

  • Consequences of Exclusion:

    • High rates of drug complications related to female-specific responses show the need for inclusive research protocols.

Dual-Function Hypothesis (De Vries)

  • Theory:

    • Sex differences exist both to ensure necessary reproductive behaviors and to promote behavioral similarities across sexes in environmentally specific contexts.

Conclusion on Sex Differences in Mental Health

  • General Findings:

    • Women show increased rates of PTSD and mood disorders, with hormonal influences suggested as a key factor.

  • Substance Abuse:

    • Different trends in timelines and behaviors concerning drug use between sexes, linkage to hormonal and social factors.

Final Note

  • Study Recommendations:

    • Suggested tasks include preparations for upcoming exams and review of discussed materials.