Key Syndromes of the Middle Stage
The complex of pathological changes in the middle stage of addiction includes a number of specific clinical and pathophysiological manifestations. Five main syndromes determine the severity of the patient's condition:
- Syndrome of physical dependence on the psychoactive substance. The body completely restructures its function to accommodate the constant presence of the drug. The primary consequence of this adaptation is the inevitable development of withdrawal symptoms upon attempting cessation.
- Syndrome of progressively increasing tolerance. Tissue sensitivity to usual doses of the substance drops rapidly. The patient is forced to constantly increase the administered amount, frequently reaching toxic doses.
- Syndrome of substance incorporation into metabolism. The drug and its breakdown products (metabolites) integrate into natural biochemical cycles, becoming an essential link.
- Personality degradation. Deep destruction of the psyche occurs, along with the loss of social connections and moral-ethical guidelines.
- Organ and tissue dysfunction. Chronic intoxication leads to systemic damage to internal organs.
Pathogenesis of Withdrawal Syndrome
Withdrawal syndrome is the main marker of established physical dependence. Its pathogenesis is based on a profound neurotransmitter imbalance in the brain.
The key link in the development of withdrawal is the accumulation of dopamine and other biogenic amines in nervous tissue. This process is triggered in response to the cessation of psychoactive substance intake. Excess catecholamines concentrate predominantly in the structures of the brain's reward system.
The severity of the clinical picture of withdrawal correlates strictly with the concentration of dopamine in the systemic circulation:
- If the blood dopamine level exceeds the physiological norm by 2-fold, the patient develops a severe presentation of withdrawal syndrome.
- If the dopamine concentration increases by 3-fold compared to normal, the condition becomes critical: acute psychosis develops, accompanied by severe disruptions in basic vital bodily processes.
In addition to the dopamine crisis, changes in the activity of other brain neurotransmitter systems play a crucial role. Long-standing hypercatecholaminemia exerts a suppressive effect on a number of protective and inhibitory pathways. Specifically, a marked decrease in the activity of the opioidergic, serotonergic, cholinergic, and GABAergic systems is recorded. Such total depletion of the neurotransmitter apparatus sharply worsens the course of withdrawal and creates an overwhelming urge in the patient for the immediate administration of a new dose of the psychoactive substance.
Mechanisms of Tolerance and Drug Integration into Metabolism
The need to constantly increase the drug dose is explained by the development of the syndrome of substance incorporation into metabolism. This phenomenon is based on structural rearrangements at the cellular level.
Repeated and regular administration of psychoactive substances provokes profound changes in the structure of neuronal membranes, including synaptic contact areas. The main biochemical shifts occur in the lipid phase of cell membranes, where a pathological excess of cholesterol and free fatty acids (FFAs) begins to accumulate.
Alterations in lipid composition directly affect the physicochemical properties of the membrane. The primary consequence of this process is a reduction in the mobility of receptors embedded within the membrane. The receptor apparatus loses its ability to adequately respond to chemical signals. It is precisely this decrease in receptor mobility that underlies the increase in substance tolerance, making a further increase in dosage inevitable to achieve the desired effect.