Aim: How do drugs affect the brain?

1
Aim How do drugs affect the brain?

• The blood brain barrier is both a physical
  barrier and a system of cellular transport
  mechanisms. It maintains homeostasis by
  restricting the entrances of potentially harmful
  chemicals from the blood, and by allowing the
  entrance of essential nutrients.

2
Blood Brain Barrier

• The BBB is semi-permeable that is, it allows
  some materials to cross, but prevents others from
  crossing.

3
General Properties of the BBB

• Large molecules do not pass through the BBB
  easily.
• Low lipid (fat) soluble molecules do not
  penetrate into the brain. However, lipid soluble
  molecules, such as barbiturate drugs, rapidly
  cross through into the brain.
• Molecules that have a high electrical charge to
  them are slowed.

4
The BBB can be broken down by

• Hypertension (high blood pressure) high blood
  pressure opens the BBB
• Development the BBB is not fully formed at
  birth.
• Hyperosmolity a high concentration of a
  substance in the blood can open the BBB.
• Microwaves exposure to microwaves can open the
  BBB.
• Radiation exposure to radiation can open the
  BBB.
• Infection exposure to infectious agents can open
  the BBB.
• Trauma, Ischemia, Inflammation, Pressure injury
  to the brain can open the BBB.

5
Adolescent brain development takes place in the
frontal lobes

• Reasoning,
• Planning,
• Emotions,
• Problem-solving

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RESEARCHERS FOUND THAT, OVERALL, GRAY MATTER
VOLUME INCREASED AT EARLIER AGES, FOLLOWED BY
SUSTAINED LOSS AND THINNING STARTING AROUND
PUBERTY, WHICH CORRELATES WITH ADVANCING
COGNITIVE ABILITIES.
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Drugs can get into the brain when

• Hyperosmolity a high concentration of a
  substance in the blood can open the BBB.
• The drugs cause neurotransmitters (dopamine,
  serotonin and nor-epinephrine) to increase in the
  synapse producing an exaggerated effect (euphoria
  or depression)

8
Cocaine Addiction

• EffectsCocaine acts on the brain and is a highly
  addictive drug. Because crack is smoked, and
  allows high doses to reach the brain rapidly,
  crack is even more addictive. Both forms of the
  drug trap a chemical called dopamine in the
  spaces between the brain's nerve cells in a part
  of the brain called the reward system. Dopamine
  stimulates and re-stimulates these nerve cells,
  making the user feel intense pleasure. The brain
  responds to the overabundance of dopamine by
  destroying some of it, making less of it, and
  shutting down the cells' receptors so they can no
  longer receive dopamine's messages

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Most drugs of abuse directly or indirectly target
the brain's reward system by flooding the circuit
with dopamine. Dopamine is a neurotransmitter
present in regions of the brain that regulate
movement, emotion, cognition, motivation, and
feelings of pleasure. The overstimulation of this
system, which rewards our natural behaviors,
produces the euphoric effects sought by people
who abuse drugs and teaches them to repeat the
behavior.