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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

Objectives

Definitions &Introduction

Multidimensional Model of addiction

Contributing factors

Neurobiology of addiction, tolerance & withdrawal

Addiction in adolescents

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

The Spectrum of Substance Use Disorders

Substance Abuse Harmful Use

Hazardous Use

moral Non-Hazardous Use

Non-User/Abstainer

Dependence Syndrome

االهرام، القعدة 22الخميس جريدة ذى 45608 العدد 136السنة 2011اكتوبر 20هـ   1432من

يصيب أصبح الذي والعصبي النفسي إنسان 450المرض مليون . األرض سطح فوق

الي وصل وحده االكتئاب , 140وان انسان مليونالي العالم في وصلت فقد والخوف القلق حاالت مليون 200أما

.. وقلق خائف انسانالي أيضا العالم في اإلدمان .. 130ووصل مدمن إنسان مليون

و مليون وجود تؤكد فإنها مصر في األرقام إنسان 200أما ألف. االكتئاب عذاب يعاني مصري

Addiction is a Complex Disease

…with biological, sociological and

psychological components

What IS addiction?

heroin addiction

cocaine addiction

alcohol addiction (“alcoholism”)

marijuana addiction

amphetamine addiction

nicotine addiction

What IS addiction?

sex addiction??

gambling addiction??

food addiction??

shopping addiction????

internet addiction????

cell phone addiction????

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.

The Development of Addiction: Genetics

Genetics May Influence How Neurobiology Interacts With Environment

However, behaviors are

complex genetic traits

EnvironmentFamily, FriendsCo-morbidityWork

GeneticsSpecific Genes

Gene/EnvironmentInteraction

The disease model-Genetics

Scientists will never find just one single addiction gene.Susceptibility to addiction is the result of many interacting genes

There is no single addiction Gene.

Why Do People Take Drugs in The First Place?

To feel goodTo have novel:

feelingssensations

experiencesAND

to share them

To feel betterTo lessen:anxietyworriesfearsdepressionhopelessness

Drugs of Abuse Engage Systems in the Motivation and Pleasure Pathwaysof the Brain

Drugs of Abuse Engage Systems in the Motivation and Pleasure Pathwaysof the Brain

Why Do PeopleAbuse Drugs?

Why Do PeopleAbuse Drugs?

Drug abuse as a Biological Concept

The reward pathway

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.

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

We Have Evidence That These Changes Can Be Both

Structural and Functional

We Have Evidence That These Changes Can Be Both

Structural and Functional

AND…AND…

Prolonged Use Changes

the Brain in

Fundamental and Lasting

Ways“Healthy” Brain

“Cocaine Addict” Brain

Addiction is a Brain Disease

Repetitive substance use:

1. Re-sets the reward system

2. Activates the brain’s stress systems

3. Impairs the pre-frontal inhibitory systems

addictionReward & well-being

motivation

Dopamine

movement

Natural Rewards

Food

Sex

Excitement

Comfort

Withdrawal: Brain Areas

Frontal Cortex Thalamus

VentralTegmentalArea (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

Withdrawal: Corticotrophin Releasing Factor (CRF)

Involvement

The CRF system mediates the affective and somatic symptoms of drug withdrawal

Heart rateBlood pressureBlood glucose

Koob, 2008, PNAS 105(26), 8809-10, Copyright 2008, National Academy of Sciences, U.S.A.

Response to stressors

Biological basis for drug tolerance (habituation)

Biological systems strive for homeostasisWhen systems are highly active, the body

responds by decreasing activity.Down-regulation is part of the biological basis

for drug tolerance (habituation)

What is down-regulation

Decrease in transmitter release (rapid)Decrease in receptor sensitivity (slower)Decrease in receptor sites (slower)

Double your pleasure, double your fun

The Development of Addiction: Adolescence

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

Neuronal Development

The Development of Addiction: Adolescence

Neuronal Development: Grey matter maturation moves fromback to front

Gogtay et al (2004) PNAS, 101 (21). Copyright 2004, National Academy of Science, U.S.A.

This imbalance leads to...

risk taking

low effort - high excitement activities

interest in novel stimuli

planned thinking

impulsiveness

PFC

The Development of Addiction: Adolescence

AmygdalaNAc

Add stress and alcohol/drug use...

PFC

AmygdalaNAc

The Development of Addiction: Adolescence

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.

Take Home Message