Major changes that occurs on the neurological system associated to age
- Neuronal Loss and Atrophy: There is a progressive loss of neurons throughout the brain, and remaining neurons may shrink or lose connections (synaptic pruning). This impacts neurotransmission and communication between brain regions.
- Neurotransmitter Changes: Levels of various neurotransmitters, chemicals that transmit signals between neurons, decline. This includes dopamine (affecting motor control and motivation), acetylcholine (impacting memory and learning), and serotonin (influencing mood and sleep).
- Changes in Myelination: Myelin, the fatty substance that insulates nerve fibers and speeds up signal transmission, can break down. This slows down neural processing and can affect cognitive and motor function.
- Decreased Blood Flow: Blood flow to the brain decreases with age, potentially due to atherosclerosis or other vascular changes. Reduced blood flow can impair brain function and increase the risk of stroke.
- Increased Sensitivity to Medications: Older adults may be more sensitive to the effects of medications due to changes in 1 drug metabolism and clearance, increasing the risk of side effects, including those affecting the CNS.
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Peripheral Nervous System (PNS) Changes:
- Decreased Nerve Conduction Velocity: The speed at which nerve impulses travel along peripheral nerves slows down. This can affect reflexes, sensation, and motor skills.
- Reduced Sensory Receptor Sensitivity: The sensitivity of sensory receptors in the skin, joints, and muscles decreases. This can impair touch, pain, temperature perception, and proprioception (awareness of body position).
- Autonomic Nervous System Changes: The autonomic nervous system, which controls involuntary functions, can also be affected. This can lead to changes in heart rate variability, blood pressure regulation, and thermoregulation.
These age-related changes can contribute to a variety of neurological conditions and can impact an individual's quality of life. It's important to note that while these changes are common, they don't necessarily lead to significant disability in everyone. Lifestyle factors, genetics, and overall health play a role.
Delirium vs. Dementia
Delirium and dementia are two distinct conditions that often affect older adults and can sometimes be confused with one another. It's crucial to differentiate between them due to their different causes, prognoses, and management strategies.
Delirium:
- Definition: Delirium is an acute and fluctuating disturbance in attention, awareness, and cognition that develops over a short period (hours to days). It's often reversible if the underlying cause is identified and treated.
- Causes: Delirium has numerous potential causes, including:
- Infections (UTI, pneumonia)
- Medications (polypharmacy, new medications)
- Dehydration
- Electrolyte imbalances
- Surgery/anesthesia
- Pain
- Hospitalization (especially in unfamiliar environments)
- Pre-existing cognitive impairment (dementia is a risk factor)
- Characteristics: Fluctuating symptoms, inattention, disorganized thinking, altered level of consciousness (hyperactive, hypoactive, or mixed), and often reversible.
Dementia:
- Definition: Dementia is a progressive and irreversible decline in cognitive function that interferes with daily life. It's a syndrome with various underlying causes.
- Causes: Dementia is caused by damage to brain cells, often due to:
- Alzheimer's disease (most common type)
- Vascular dementia (due to stroke or other vascular problems)
- Lewy body dementia
- Frontotemporal dementia
- Parkinson's disease
- Characteristics: Gradual onset, progressive decline in memory, language, executive function, and other cognitive domains, often irreversible.
Similarities:
- Both can affect cognition, behavior, and functional abilities.
- Both are more common in older adults.
- Both can be challenging to manage.
Differences:
| Feature | Delirium | Dementia |
|---|---|---|
| Onset | Acute, sudden | Gradual, progressive |
| Course | Fluctuating, often reversible | Progressive, irreversible |
| Attention | Impaired | May be relatively preserved early on |
| Awareness | Altered | Usually clear until later stages |
| Thinking | Disorganized | Impaired, but less fluctuating than delirium |
| Underlying Cause | Identifiable medical cause often present | Underlying brain disease |
It is crucial to differentiate delirium from dementia as delirium is often a medical emergency requiring prompt treatment of the underlying cause. Dementia, while not reversible, benefits from early diagnosis and management to slow progression and improve quality of life. Sometimes, an individual can have both delirium superimposed on dementia, making diagnosis even more complex.
Age-Related Changes in the Neurological System
The neurological system, encompassing the central nervous system (CNS) and peripheral nervous system (PNS), undergoes several changes with age. These changes can impact cognitive function, motor skills, sensation, and overall neurological health.
Central Nervous System (CNS) Changes:
- Brain Volume and Weight Reduction: The brain gradually shrinks in size and weight due to neuronal loss and atrophy. This reduction is more prominent in certain areas, such as the prefrontal cortex (responsible for executive functions) and the hippocampus (involved in memory).