Title : Neuroscience of addiction: What & How

Addiction (be it nicotine, alcohol, and drugs of abuse) is a major public health problem and millions of people die. The economic consequences of addiction are staggering all over the World. Although great strides have been made in understanding the nature of addiction, it is still not well understood.

Addiction can be considered a chronic brain disease that affects neurotransmission between neuronal circuits controlling behavior and emotions. It was historically viewed as a disease of “weak personality” and was not systematically addressed by the scientific and medical communities until the latter half of the 20th century. However, addiction is now commonly accepted as disease caused by the impact of the alcohol on the brain (direct effects and neuroadaptations) modified by environmental factors.

In the past 50 years, number of dramatic breakthroughs have been reported on the neurobiology of addiction. Neurobiological substrates for the reinforcing effects have been largely identified both at the initial site of action and in the circuitry involved. In human studies, decrease in dopaminergic function has been identified as a key element of addiction, lending support for research on the role of dopamine in addiction. Thus, importance of the dopaminergic reward pathway, as one of the key common sites of action is of great significance.

The current understanding of addiction stems from the idea that it is produced by interaction of genetic, environmental, psychosocial, behavioral, and other factors, causing long-term alterations in the brain. In short, addiction can be conceptualized as a disorder that moves from impulsivity to compulsivity in a collapsed cycle comprised of three stages: Impulsivity and positive reinforcement often dominate the first stage, driving the motivation for drug seeking, and compulsivity and negative reinforcement dominate the terminal stages of the addiction cycle.

Thus, addiction results from repeated long-term exposure to substance abuse/alcohol, resulting in changes in central nervous system, especially in the midbrain dopamine system.

Involvement of various Neurotransmitters, Reward Pathways followed by Addiction and stress would be discussed

However, it must be emphasized that

• Addiction is the result of interaction of various factors. The neurobiological pathways modulating reward, stress resiliency and behavior inhibition have underlying addiction liability
• In developing a conceptual understanding of alcohol addiction, it must be acknowledged that compulsive alcohol or drug use cannot be understood from any single level. Variation in the neurobiology of addiction is genetically influenced by correlation of addiction liability with heritability
• It is also known that stress being an environmental factor can have an impact on neurological systems. it can trigger imbalances that could result in co-morbidity.

Dr. Meera Vasami is a Tenured Professor and Director of the WHO Collaborative National Drug Dependence Treatment Center at All India Institute of Medical Sciences. She holds a PhD from University of Delhi and completed postdoctoral training at AIIMS. Dr. Vasami received prestigious awards from the National Institute on Drug Abuse, chaired Addiction sessions at American Psychiatric Association meetings (2002–2012), and was awarded a UN Fellowship at the University of Glasgow. She is an elected Fellow of the Royal Society of Chemistry and Member of the National Academy of Medical Sciences. She has been invited to publish chapters on addiction for “Elsevier Publications”; in “International Series of Addiction” Praeger Publications, USA"; in "Advances in Psychology “Nova Science Publishers’, Inc. USA". in "Genomics and Health in the Developing World” Oxford Publishers" ; in "Substance Use Disorder, Indian Publishers".