Neurotransmitters and Cognitive Aging

Cognitive Aging

• Changes in dopamine levels may play a major role in cognitive aging, affecting effortful and automatic processes
• Abnormal processing of serotonin is related to cognitive decline
• Damage to structures that use acetylcholine is associated with memory decline
• The Positivity Effect: Older adults are more motivated to derive emotional meaning from life and maintain positive feelings than younger adults
• Theory of Mind (ToM): The ability to understand that others have beliefs, desires, and viewpoints different from our own; research shows age-related decline in ToM (over 75)

Executive Functioning

• Difficulty focusing solely on relevant information due to WMH and reduced volume of prefrontal cortex
• Memory decline due to specific structural changes (e.g., the hippocampus)
• Better emotional regulation with age
• Increased processing of positive emotional information with age

Social-Emotional Cognition

• Older adults may rely more on automatic judgment processes than reflective processing

Theories and Models of Brain-Behavior Changes Across Adulthood

The Parieto-Frontal Integration Theory (P-FIT)

• Proposes that intelligence comes from a distributed and integrated network of neurons in the parietal and frontal areas of the brain

CRUNCH (Compensation-Related Utilization of Neural Circuits Hypothesis)

• Additional mechanisms at work in aging brains, overutilizing other regions in the left hemisphere on demanding tasks

STAC-r (Scaffolding Theory of Cognitive Age—Revised)

• Default network theory holds that when cognitive demands are made on the brain, the default network is suppressed
• Neural resource enrichment and depletion interact with neural plasticity to account for age-related changes in cognitive functioning

Information-Processing Model

• Based on a computer metaphor
• Three assumptions:
  • Active processing: the individual is actively involved in transforming incoming information
  • Both quantitative and qualitative aspects of performance can be examined
  • Information is processed through a stage-like series of "stores"

Respiratory System

• Changes in the respiratory system include shortness of breath, which may result in a reduction of activity in older adults
• Chronic obstructive pulmonary disease (COPD) is a family of diseases that includes emphysema and chronic bronchitis

Biological Changes

Female Reproductive System

• Menopause and climacteric: the transition from being able to have children to the cessation of ovulation (usually begins in the 40's and complete by mid-50's)

Male Reproductive System

• Sperm production declines gradually with age
• Testosterone levels decline gradually with age
• Prostate gland enlargement with increasing age

Central Nervous System

• Neurons: individual brain cells, with changes occurring at the level of individual brain cells
• Dendrites: where neurons receive chemical information from other neurons
• Synapses: chemicals are sent out into the gap between neurons to be picked up by a neighboring neuron's dendrites

Structural Changes in Neurons

• Aspects of growth and loss of dendrites during the life span
• Neurofibrillary tangles: when fibers of the axon become twisted to form spiral filaments
• Neuritic plaques: occur when dying neurons collect around a core of protein

Changes in Neurotransmitters

• Acetylcholine: decreases with age, research has speculated that abnormally low levels are related to Alzheimer's disease
• Dopamine: decreases with age, an extreme decline in the dopamine system is related to Parkinson's disease

Autonomic Nervous System

• Regulating body temperature: older adults have a harder time dealing with heat and cold, putting them at risk for hypothermia and hyperthermia
• Sleep and aging: older adults have more difficulty falling asleep and staying asleep, with changes in circadian rhythms

Genetic and Environmental Factors in Average Longevity

• Genetic factors: being born into families who have lived long is a strong predictor of longevity
• Environmental factors: disease, toxins, health behaviors/lifestyle, and socioeconomic status can shorten lives