Hitler regularly consumed methamphetamine, barbiturates, amphetamine, opiates and cocaine. These medications include central nervous system stimulants such as methylphenidate, modafinil, amphetamine, and dextroamphetamine. Ephedrine is a substituted amphetamine and a structural methamphetamine analogue. Methylphenidate is a stimulant with an addiction liability and dependence liability similar to amphetamine. Methamphetamine is most structurally similar to amphetamine. Propylhexedrine is used recreationally in a similar manner to amphetamine, methamphetamine and dextroamphetamine. It may be mixed with other substances such as ephedrine, amphetamine, and methamphetamine. Mephedrone is a synthetic stimulant drug of the amphetamine and cathinone classes. The behavioral symptoms are similar to those of an amphetamine, cocaine or caffeine overdose. Pseudoephedrine is a sympathomimetic drug of the phenethylamine and amphetamine chemical classes. Adderall is an unequal mixture of both amphetamine enantiomers. Evidence for epigenetic changes stemming from amphetamine and cocaine abuse derives from animal studies. Adderall and Mydayis are trade names for a combination drug containing four salts of amphetamine. The severity of overdose symptoms increases with dosage and decreases with drug tolerance to amphetamine. The use of cocaine or an amphetamine with cigarettes can result in chain smoking.