Final answer:
The statement is False. There is a relationship between the severity of the disorder and the amount of the substance.
Step-by-step explanation:
The statement, 'There is essentially no relationship between severity of the disorder and the amount of this substance' is False. In fact, there is a relationship between the severity of the disorder and the amount of the substance. For example, in the case of substance use disorders, individuals who consume larger amounts of a substance are more likely to experience more severe symptoms and negative consequences.