PSYC_2320_Abnormal_Psychology_Chapter_2

Psychological Disorders - Chapter 2: Research Methods

Critical Thinking and Ethics in Research

• Psychology relies on the scientific method, making it a science.

• Translational research bridges the gap between basic science and clinical application.

• Scientific Method:

  • Identify the Problem: Must be empirically investigable.

  • Conduct Background Research: Understand existing knowledge.

  • Formulate a Hypothesis: A testable statement.

  • Test the Hypothesis: Experiments are the most conclusive.

  • Analyze the Results: Using statistical analyses.

  • Report Your Results: Whether the results support or do not support the hypothesis. If not supported, formulate a new hypothesis.

• Translational Research:

  • Translation from basic science to human studies.

  • Translation of new knowledge into clinical practice, ultimately improving health.

• Critical thinking involves examining assumptions, evaluating evidence, identifying hidden agendas, and assessing conclusions.

• Steps to improve critical thinking:

  • Consider underlying motives.

  • Evaluate evidence quality.

  • Generate alternative explanations.

  • Avoid emotions and personal experiences in evaluation.

• Core Principles of Ethics in Research, outlined in the Belmont Report:

  • Respect for persons.

  • Beneficence.

  • Justice.

• IRB (human participants) or IACUC (animal subjects) provide oversight.

• The Informed Consent Process:

  • Ensures participant understanding.

  • Clarifies voluntary participation.

  • Considers risks and benefits.

  • Ensures fair participant selection.

Research at the Cellular Level

• Neuroanatomy: Study of the nervous system's structure.

• Human Nervous System:

  • Central Nervous System (CNS): Brain and spinal cord.

  • Peripheral Nervous System (PNS):

    • Somatic nervous system: Controls sensation and muscle movement.

    • Autonomic nervous system.

• Neurons: Brain contains millions of nerve cells.

  • Soma: Cell body.

  • Dendrites: Receive signals.

  • Axon: Transmits signals.

  • Axon terminals.

  • Synapses: Junctions between neurons.

• Anatomy of a Neuron:

  • Dendrites: Bushy, branch-like structures that emerge from the neuron's cell body and receive signals from nearby neurons.

  • Soma: The cell body that contains the nucleus, which includes DNA, and other structures that support and nourish the neuron.

  • Axon: A cable-like extension that transmits the signal away from the soma toward the target of communication.

  • Myelin Sheath: A fatty substance that insulates the axon (similar to the plastic coating on electrical wires), thereby improving the strength and speed of the signals.

  • Terminal Buttons: Structures at the ends of the branches that extend out from the axon. They release chemicals into the space between neurons.

• Parts of the Brain:

  • Brain stem: Controls fundamental biological functions.

    • Medulla, pons, and cerebellum: Regulate breathing, heartbeat, and motor control.

  • Midbrain: Coordinates sensory information and movement.

  • Thalamus: Brain’s relay station for sensory information.

  • Hypothalamus: Regulates bodily functions (homeostasis).

  • Forebrain:

    • Limbic system: Amygdala, cingulate gyrus, and hippocampus; involved in emotions and impulses.

    • Basal ganglia: Structures that inhibit movement.

    • Cerebral cortex: Largest part of the forebrain; responsible for reasoning, abstract thought, perception of time, creativity, and uniquely human abilities.

      • Divided into two hemispheres, each with four lobes: Parietal, temporal, occipital, and frontal.

• The Peripheral Nervous System:

  • Sensory-somatic nervous system

  • Autonomic nervous system:

    • Sympathetic nervous system: Activates physical readiness.

    • Parasympathetic nervous system: Returns body to resting state.

• The Endocrine System:

  • Regulates bodily functions using hormones produced by glands.

  • Hormones are chemical messengers released into bloodstream.

  • Pituitary gland: “Master gland” controlling many endocrine functions.

  • Hypothalamus oversees the pituitary gland.

  • Glands in the periphery oversee body function (adrenals, pancreas, thyroid).

Neurotransmitters

• Nervous system communication is both electrical and chemical.

• Neurotransmitters are chemicals that relay signals between two neurons.

• Neurotransmitters released when electrical signal reaches axon terminal.

• Psychiatry studies drug treatments on specific neurotransmitters.

Genetics

• Genetics basics:

  • DNA (deoxyribonucleic acid): “Building block of life.”

  • Each person has approximately 30,000 genes.

  • 23 pairs of chromosomes.

  • There are six different biological sexes: X, XX, XXY, XY, XYY, and XXXY

• Behavioral genetics:

  • Family, twin, and adoption studies.

  • Examine whether patterns are due to genetics or environment.

• Family Studies:

  • Family pedigree studies: Examine disorder likelihood among family members.

  • Proband: The family member with the disorder.

  • Family history and study method.

  • Shared environmental factors.

• Adoption Studies:

  • Compares child to biological and adoptive parents.

  • Similarities with biological parents suggest genetics.

  • Similarities with adoptive parents suggest environment.

• Twin Studies:

  • Compares monozygotic (MZ) and dizygotic (DZ) twins.

  • Behavioral differences in MZ twins indicate environmental influences.

  • MZ twins separated in infancy allow comparison of genetics and nonshared environmental factors.

• Molecular Genetics:

  • How specific genes are related to a disorder.

  • Three methods:

    • Genome-wide linkage analysis: Examines family members to narrow genetic regions.

    • Candidate gene association study (CGAS): Compares genes in groups with and without a disorder.

    • Genome-wide association study (GWAS): Genetic variations are tested against matched controls.

• Gene-Environment Interactions and Correlations:

  • Gene-Environment Interaction: When environmental factors change the expression of pre-determined genotypes. Example: Poor childhood nutrition (environment) affects an adult's ultimate height (genetics).

  • Gene-Environment Correlation: When the genotype influences the environment. Example: Someone who is introverted (genetics) actively selects more solitary activities (environment).

Research at the Individual Level

• Case study: Comprehensive description of an individual or group.

  • Provides detailed narratives of behavior and treatment.

  • Benefits:

    • Examines rare phenomenon.

    • Generates hypotheses.

    • Illustrates important clinical issues.

  • Variations and Limitations:

    • Amount and type of data may vary.

    • Standardizing procedures allows combining results.

    • Limited in ability to understand psychological symptoms.

    • Does not allow conclusions about causes.

• Single-case designs: Experimental study with an individual.

  • Individuals are part of both experimental and control conditions.

  • Can lead to causal inference.

  • Requires fewer resources.

  • Allows focus on individual patterns of change.

  • Design strategies:

    • ABAB or reversal design.

    • Multiple baseline studies.

  • Limitations:

    • Results are not generalizable.

    • Do not address individual differences.

    • Reversing treatment may be unethical or impractical.

Research at the Group Level

• Correlation methods:

  • Examines the relationship between variables or conditions.

  • Correlation coefficient indicates direction and strength of a relationship.

    • Positive correlation.

    • Negative correlation.

    • The coefficient ranges from -1.0 to 1.0.

  • Correlation is not causation.

• Experimental group designs:

  • Experimental group: Exposed to treatment.

  • Control group: Comparison group.

  • Independent variable: Controlled by the researcher.

  • Dependent variable: The outcome measure assessed.

  • Random assignment: Equal chance of being assigned to either group.

• Other considerations of randomized control trials:

  • Analogue vs. clinical sample.

  • Internal vs. external validity.

  • Effectiveness vs. efficacy research.

  • Placebo control.

  • Single-blind and double-blind procedures.

  • Clinical vs. statistical significance.

Improvement of Diversity in Group-Based Research

• Samples often restricted.

• Historical exclusion of women in medical research.

• Underrepresentation of BIPOC (Black, Indigenous, and People of Color).

• Suggestions to improve:

  • Select assessments valid for BIPOC samples.

  • Design accessible times and locations.

  • Work with community to engender trust.

  • Increase diversity on research team.

  • Provide compensation.

Cross-Sectional and Longitudinal Cohorts

• Cohort: Group sharing a common characteristic moving forward in time.

• Cohort studies examine incidence, causes, and prognosis.

• Two designs:

  • Cross-sectional design: Participants assessed once.

  • Longitudinal design: Multiple measurements over time with the same individuals.

Research at the Population Level

• Epidemiology: Focuses on the prevalence and incidence of mental disorders.

  • Prevalence: Number of cases in a population at a given time.

    • Point prevalence.

    • Lifetime prevalence.

  • Incidence: Number of new cases that emerge.

• Epidemiological research designs:

  • Observational epidemiology: Documents presence of disorders.

  • Experimental epidemiology: Manipulates exposure to causal or preventive factors. This might be scientist manipulating exposure to either causal or preventive factors