One of the more common reasons that people hold the last syllable of a word is because they have a lisp. A lisp is a functional disorder, which means the cause is not known. Speakers with lisps have difficulty producing "S" and "Z" and may produce a different sound such as "TH," which they often then hold. Many children have this speech disorder and then grow out of it, however, there are a number of adults who continue to produce a lisp.
Stuttering, also sometimes referred to as stammering, is a speech disorder characterized by the repetition of certain sounds and the inability to produce others. However, in some speakers stuttering may also cause prolonged syllables. This disorder may not be consistent and the problem is often worse when the speaker has to speak in front of a group. Stuttering affects people of all ages, but is often seen in young children between the ages of 2 and 5.
Dysprosody is an extremely rare speech disorder. This is a neurological problem that can manifest itself in a number of ways including the timing, cadence and intonation of words, and speakers with dysprosody may hold the last syllable in a word. This is a rare condition and not fully understood. This condition is similar to Foreign Accent Syndrome, which is another neurological condition that causes the speaker to lose his native accent and suddenly adopt a new one.
Other languages have different stresses and intonation than the ones commonly used in English pronunciation. When a foreign speaker uses English they may hold the last syllable of word if that is the common intonation in their native language. Foreign speakers who are not familiar with English may also hold the last syllable of a word if they are searching for the next word or are unsure of what they should say next.