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3. Biological Considerations of Addiction
Dr. Hani Hamed Dessoki, M.D.Psychiatry
Prof. Psychiatry
Chairman of Psychiatry Department
Beni Suef University
Supervisor of Psychiatry Department
El-Fayoum University
APA member

4. Objectives
Definitions &Introduction
 Multidimensional Model of addiction
Contributing factors
Neurobiology of addiction, tolerance & withdrawal
Addiction in adolescents

5. Some definitions
Drug abuse – use of hard drug in a manner or
amount that is harmful or potentially harmful.
Drug addiction – compulsive use of hard drug in the
presence of harm (psychological, physical or social).
Drug dependence – when one needs the drug to
avoid withdrawal state or to maintain functional
status

6. The Spectrum of Substance Use
Disorders
Dependence Syndrome
Substance Abuse
Harmful Use
Hazardous Use
moral
Use
Non-Hazardous
Non-User/Abstainer

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8. Addiction is a Complex Disease
…with
biological, sociologic
al and psychological
components

9. What IS addiction?
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heroin addiction
cocaine addiction
alcohol addiction (“alcoholism”)
marijuana addiction
amphetamine addiction
nicotine addiction

10. What IS addiction?
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sex addiction??
gambling addiction??
food addiction??
shopping addiction????
internet addiction????
cell phone addiction????

11. Addiction Is Multidimensional
Addiction is influenced by many factors including
biological (neurobiology), social (family, friends,
work) and personal (psychological processes
relating to addiction).
Thus while the potential for addiction is related to
neurobiology in some degree, situational (social
circumstances) factors play a substantial role.
Indeed, many people use alcohol and drugs and
do not become addicted.

12. The Development of
Addiction: Genetics
However,
behaviors are
complex genetic
traits
Environment
Family, Friends
Co-morbidity
Work
Gene/
Environment
Interaction
Genetics
Specific Genes
Genetics May Influence How Neurobiology Interacts With
Environment

13. The disease model-Genetics
Scientists will never find just one single addiction gene.
Susceptibility to addiction is the result of many interacting genes

14. Why Do People Take Drugs in
The First Place?
To feel good
To have novel:
feelings
sensations
experiences
AND
to share them
To feel
better
To lessen:
anxiety
worries
fears
depression
hopelessness

15. Why Do People
Abuse Drugs?
Drugs of Abuse
Engage Systems in
the Motivation and
Pleasure Pathways
of the Brain

16. Drug abuse as a Biological
Concept

17. The reward pathway

18. This system generates signals in a part of the
brain called the ventral tegmental area (VTA) that
result in the release of the chemical dopamine
(DA) in another part of the brain, the nucleus
accumbens (N-Ac) .
This release of DA into the N-Ac causes feelings
of pleasure.
Other areas of the brain create a lasting record
or memory that associates these good feelings
with the circumstances and environment in
which they occur.

19. Neurobiology/mechanism of drug
addiction
Three mechanisms at the synaptic junction of
brain nerve cells
• Neural – acute exposure
• Cellular (regulation of ion channels and electrical
properties) – long term exposure
• Molecular mechanisms – long term exposure

20. AND…
We Have Evidence That
These Changes Can Be Both
Structural and Functional

21. Addiction is a Brain Disease
Prolonged Use
Changes
the Brain
“Healthy”
Brain
“Cocaine
Addict” Brain
in
Fundamental
and Lasting
Ways

22. Repetitive substance use:
1. Re-sets the reward system
2. Activates the brain’s stress systems
3. Impairs the pre-frontal inhibitory systems

23. movement
motivation
Dopamine
addiction
Reward & well-being

26. Natural Rewards
Food
Sex
Excitement
Comfort

27. Withdrawal: Brain Areas
Frontal Cortex
Thalamus
Ventral
Tegmental
Area (VTA)
Amygdala
Locus Coeruleus
The thalamus is activated when
drugs of abuse are abruptly ceased
LC has projections to
frontal cortex, limbic
cortex, and amygdala

28. Withdrawal: Corticotrophin
Releasing Factor (CRF)
Involvement
The CRF system mediates the affective and
somatic symptoms of drug withdrawal
Koob, 2008, PNAS 105(26), 8809-10, Copyright 2008, National Academy of Sciences, U.S.A.
Heart rate
Blood pressure
Blood glucose
Response to stressors

29. Biological basis for drug tolerance
(habituation)
Biological systems strive for homeostasis
When systems are highly active, the body
responds by decreasing activity.
Down-regulation is part of the biological basis
for drug tolerance (habituation)

30. What is down-regulation
Decrease in transmitter release (rapid)
Decrease in receptor sensitivity (slower)
Decrease in receptor sites (slower)

31. Double your pleasure,
double your fun

32. The Development of Addiction:
Adolescence
Neuronal Development
 The back of brain matures first…
• sensory and physical activities favoured over complex,
cognitive-demanding activities
• propensity toward risky, impulsive behaviors
 group setting may promote risk taking
• poor planning and judgment

33. The Development of Addiction:
Adolescence
Neuronal Development: Grey matter maturation moves from
back to front
Gogtay et al (2004) PNAS, 101 (21). Copyright 2004, National Academy of Science, U.S.A.

34. The Development of Addiction:
Adolescence
This imbalance leads to...
risk taking
low effort - high excitement activities
interest in novel stimuli
PFC
planned thinking
impulsiveness
Amygdala
NAc

35. The Development of Addiction:
Adolescence
Add stress and alcohol/drug use...
PFC
Amygdala
NAc

36. Take Home Message
The classic anatomical areas of the brain involved in the
reward pathway include the nucleus accumbens, ventral
tegmental area and the prefrontal cortex..
Dopaminergic activity is the final chemical action in most
behaviours relating to reward.
The changes in addiction can be structural and functional.