Dr E K DordoyeBSc, MBChB

Post. Grad. Cert – HRMResident – Faculty of Psychiatry, GCPS, WACP

Objectives Functional Anatomy of the Brain Brain and Behaviour Different drugs of abuse How drugs alter behaviour Cause of drug abuse Cycle of change

Know gross anatomy of the brain Know the various drugs of abuse Understand the chemical basis of behaviour Understand why drugs are abused

• The cerebrum– 2 cerebral hemispheres• Frontal lobe• Temporal lobe• Parietal lobe• Occipital lobe

– Subcortical nuclei• Thalamus• Hypothalamus• Basal Ganaglia

• Brain stem– Midbrain– Pons– Medulla oblongata

• Cerebellum

The cerebral Hemispheres are the seat of intelligence and where we take conscious decisions

The frontal lobe has the centres for voluntary movement and planning & execution of the plans i.e. Executive function

The temporal lobe has the language and hearing centres

The parietal lobe receives and interprets sensory information

The occipital lobe receives and interprets visual stimuli

The subcortical nuclei controls some of the involuntary actions and also serve to relay information to the cerebral hemispheres

The brainstem controls most of the automatic behaviours we exihibit such falling asleep and waking, breathing and walking smoothly without looking whether the floor is high or low

The cerebellum also fine tunes voluntary movements

The limbic system comprise some of the sub-cortical nuclei and the frontal lobe

This system controls our emotions and feelings and also has the reward centre which controls our pleasure seeking behaviour

These are the centres which when activated by psychoactive drugs make an individual want to repeat that “behaviour” that activated the centre

The brain’s basic units are the neurones by which the brain communicates with other parts of the body and brain itself.

Neurones do not communicate directly with another directly as they never touch each other but rather but via chemicals called neurotransmitters across the (synaptic) gaps between neurones

Drugs or chemicals that can affect the function of neurotransmitters are called Psychoactive Substances

[psych = mind, substance = drug or chemical]

Since these chemicals are the means by which the brain interpret information coming to it, then an imbalance of these neurotransmitters will give “misinformation” to the brain and a consequent misintepretation

Thus, neurotransmitter imbalance gives misinformation and the (mis)interpretation is the reason for symptoms of mental illness

Also, psychoactive substances, which are commonly abused, affect these neurotransmitters and hence consequent misinterpretation and behaviour

Our behaviour is as a result of the interpretation our brains give to the environment

For instance, you may begin to remove your clothes now if you brain interprets that you are currently in your bathroom

In essence our behaviour is as a result of chemicals in our brains at any point in time and changing them will change our behaviours

• Alcohol• Beer, Stout (Guinness or Castle Milk Stout)• Palm wine, Pito• Gin e.g. Vodka, Schnnapps, akpeteshie

• Nicotene• Stimulants– Cocaine– Amphetamines

• Opioids– Codeine– Heroine– Morphine– Methadone

• Cannabis or marijuana• Anxiolytics• Diazepam or Valium• Lorazepam or Ativan

Alcohol and drug abuse is as a result of multiple interacting factors.

Initial experimentation of alcohol or drug is usually as a result of:◦ Alcohol or drug availability◦ Social acceptability e.g. Drinking at a social

gathering like wedding, at death of a loved one etc

◦ Peer pressure e.g smoking to join a cliché of friends

The continual use of the substance of abuse will depend on:◦ Personality e.g. Impulsive individuals◦ Individual’s biology e.g. Genetic or Familial,

especially in the male lineage◦ The effect of the drug e.g. Cocaine causes a lot of

psychological craving and activate the limbic system like sex

◦ Successful recovery from dependence In all this learning plays a pivotal role in the

maintenance of addiction