228 Introduction to Anatomy and Physiology
causes widely varying symptoms. Symptoms can
range from changes in attention span or behavior
to uncontrolled convulsions, depending on the
type of epilepsy and area of the brain affected.
Epilepsy may be caused by a disease or
injury that affects the brain, although in many
cases the cause is unknown and genetics may
play a role. Onset of epilepsy can happen at any
age but occurs most frequently in infants and the
elderly.
Epileptic seizures in a given individual are
of a relatively consistent nature. Before a seizure,
some people have an unusual sensation such as
tingling, a strange smell, or an emotional change.
This signal is referred to as an aura.
Epilepsy can be controlled with medication
in most, but not all, people. Some types of
epilepsy completely disappear after childhood.
However, more than 30% of people with epilepsy
are not able to control seizure incidence with
medications. If epileptic seizures are caused
by an observable problem, such as a tumor,
abnormal blood vessels, or bleeding in the brain,
surgery to address these issues may eliminate
further seizures.
Parkinson’s Disease
Parkinson’s disease (PD) is one of the most
common nervous system disorders among
the elderly. It is characterized by tremors,
diffi culty with initiating movements—especially
walking—and defi cits in coordination. PD most
often develops after the age of 50, although a
genetic form of the disease may occur in younger
adults. Men and women are equally affected.
PD is characterized by slow but progressive
destruction of the brain cells responsible for
production of the neurotransmitter dopamine,
which plays a role in motor function. Without
dopamine, the cells in the affected part of the
brain cannot initiate nerve impulses, leading to
progressive loss of muscle function. The cause of
this condition is unknown.
The symptoms of PD tend to begin with
a mild tremor of slight stiffness or weakness
in one or both of the legs or feet. As brain cell
destruction progresses, symptoms of motor
dysfunction affecting one or both sides of the
body may include
• diffi culty initiating and continuing
movements;
• problems with balance and gait;
• stiff, painful muscles and tremors;
• slowed movement, including blinking;
• loss of fi ne motor control with hand
movements;
• slowed speech, drooling, and diffi culty
swallowing;
• loss of facial expression; and
• stooped posture.
Autonomic and cognitive functions can also
be impaired, as characterized by
• sweating and fl uctuations in body
temperature;
• fainting and inability to control blood
pressure;
• constipation;
• confusion or dementia; and
• anxiety or depression.
Currently, no cure for PD exists; the
goal of treatment is control of symptoms. If
untreated, the disorder will progress, resulting
in deterioration of all brain functions and
early death. The medications prescribed for
Parkinson’s patients are designed to increase the
levels of dopamine in the brain.
Dementia and Alzheimer’s Disease
Dementia (deh-MEHN-shee-a) is a
condition involving loss of function in two or
more areas of cognition including memory,
thinking, judgment, behavior, perception, and
language. Dementia usually occurs after the age
of 60, and risk increases with advancing age.
Although forgetfulness is often the fi rst sign of
dementia, occasional forgetfulness alone does
not qualify as dementia.
Dementia can be caused by disruption in the
blood supply to the brain, as in stroke or related
disorders. However, the single most common
cause of dementia is Alzheimer’s disease.
Alzheimer’s disease (AD), or senile dementia,
is a progressive loss of brain function with
major consequences for memory, thinking, and