gsmith - welcome and thank you for coming with information that
might help in finding Steven.
The sudden pause of up to 20 seconds as described by gsmith may be an indication of an issue with the way the brain is wired. I wonder if Steven ever had a noticeable seizure or whether he
has had these pauses in speech or activity in the past. It may not have been diagnosed.
Webmd.com talks about two types below. I just want to be careful not to label anyone with anything based on what we know at this time. Perhaps KCN has more information.
I don't think he was experimenting with drugs. My thought is that he was seen by someone
regarding feeling uneasy or anxious and was prescribed a medication.
From webmd:
Absence seizures cause a short loss of consciousness (just a few seconds) with few or no symptoms. The patient, most often a child, typically interrupts an activity and stares blankly. These seizures begin and end abruptly and may occur several times a day. Patients are usually not aware that they are having a seizure, except that they may be aware of "losing time."
http://www.webmd.com/epilepsy/guide/types-of-seizures-their-symptoms
Complex partial seizures, by definition, include impairment of awareness. Patients seem to be "out of touch," "out of it," or "staring into space" during these seizures. There may also be some "complex" symptoms called automatisms. Automatisms consist of involuntary but coordinated movements that tend to be purposeless and repetitive. Common automatisms include lip smacking, chewing, fidgeting, and walking.
http://www.webmd.com/epilepsy/guide/types-of-seizures-their-symptoms?page=2