The causal conditions for psychiatric disorders include: stress, depression, illicit psychoactive drug misuse, psychotropic medication (antidepressants and antipsychotics), autistic spectrum disorders, Tourette syndrome and attention deficit hyperactivity disorder (ADHD). This chapter discusses the treatment and diagnostic options for these conditions. A variety of commonly used recreational drugs can act either directly or indirectly to cause seizures. In the UK these include opioids, stimulants (cocaine, amphetamine, methylenedioxymethamphetamine), marijuana, benzodiazepines, barbiturates, club drugs (phencyclidine and ketamine), hallucinogens, and inhalants. The core features of autism and related disorders (ASD) are qualitative abnormalities in reciprocal social interactions, patterns of communication, and a restricted stereotyped repetitive repertoire of interests and activities. Attention deficit hyperactivity disorder is a childhood-onset illness characterized by severe inattention, hyperactivity, and impulsivity. Diagnosis of ADHD is clinical and based upon fulfilling the DSM-IV criteria.