Flight of ideas is a symptom of several psychiatric disorders, most especially bipolar I disorder during manic phases and schizophrenia, and more rarely with conditions like Attention Deficit and Hyperactivity Disorder (ADHD). This rapid flow of talk that appears to jump from subject to subject, often with loose associations or plays on words between topics. Very young children may exhibit flight of ideas normally, though as they mature they usually grow out of this. The condition is considered unusual in people who are old enough to stay on topic, but cannot seem to, even if they are trying.
As stated, rapid talking quickly shifts from one subject to another without transitions or breaks, and can continue for long periods. For example, a person might say "Look at the sun, sun, sun, bun, bun, honey bun, bunny hon, bun in the oven." Another person might just shift from topic to topic like this: “I don’t know what I’m going to do about Tony. Well there’s the neighbor’s dog barking again. Did you realize there are three weeks left until June? Man it’s hot in here. There’s a sale down at the mall I just can’t miss.”
The second example makes it clear that there can be little relationship of one subject to another, as if the mind can’t focus and can’t control thought direction. Thoughts are on flight, coming in rapid-fire sequence that makes little sense. Many people with psychiatric disorders state they feel this flight of ideas whether or not they voice them, and this can have a disorienting effect, or it can feel like the person’s ability to think is particularly augmented.
This condition occurs for people with bipolar disorder mostly when they're in a manic state, and there’s argument as to whether those who have bipolar II and who are in hypomanic states express this trait often. In schizophrenia, flight of ideas might occur anytime the illness is in progress and thoughts could be even more disconnected or reference delusions of the schizophrenic. In the example above, the ideas are relatively mundane, but in either bipolar mania or schizophrenia, thoughts can bear much less on the real and be difficult to understand. ADHD ideas could vary in quality of reality too, depending on things like age of person expressing them.
In all cases, this symptom is evidence of a mind at great unrest, and a person who is probably not responding well to treatment. People with longterm bipolar disorder are likely expressing that medications need to be changed or adjusted because they are undergoing med destabilization. Schizophrenics, too, who are already in treatment, are likely to need additional help at this stage.
This symptom can also be one of the first notable symptoms of either of these diseases or of ADHD. What this means is that flight of ideas suggests medical care is required so that the person does not destabilize further. Even with medication adjustments or first treatment of an illness, it may take a while for meds to resolve flight of ideas.