An individual who is bipolar and depressed, if they are in the depressed phase of the illness, will have depressive symptoms no different than someone who has unipolar major depression. Bipolar individuals will have on average three of these depression episodes before their first manic or elevated state.
We may not know who the individuals at risk for bipolar disorder are, but an individual who is bipolar will go from depression and at some point have what is called manic or hypomanic episodes. Full blown manic episodes are described as things such as, decreased need for sleep for an extended period of time and still feeling rested, racing thoughts, feeling grandiose, inflated sense of self esteem, feeling raced and pressured, having pressured speech and pressured thoughts. People often get very impulsive, they may get in trouble with the law, make poor decisions in terms of spending and sexual activities.
These are typical common symptoms of overt mania and these symptoms can differ from one person to another and can even differ within the same individual over time. In extreme mania where someone may actually need hospitalization they may also have psychotic episodes. Psychotic symptoms may mean that there is inflated sense of grandiosity where the individual actually believes that they have specific powers. They believe they have the ability to do things that may not be real. This is what is called bipolar type 1. Those are people who have depressions but overt manic episodes.
Hypomania is also bipolar but is trickier to diagnose. Hypomania and depression, when those two exist is called bipolar type 2. Hypomania is very similar to mania except you may have a less intense form of when someone gets high. In both mania and hypomania an individual may have irritability, but very common in bipolar type 2, you can see a lot of irritability. A lot of people say it just feels like I'm going to scratch somebody's eyes out, they have very little patience. They are very irritable, they are always on the go, they may be very racy and may also be very creative. This sort of behavior when followed by a depression interspersed is a sign that this person may have bipolar type 2.
When a depressed person who comes into a doctors office and they go through a history, the doctor may not know that the individual is bipolar, but if the doctor puts them on an antidepressant and they come back the next week and say " I feel wonderful", that's either a placebo response to the antidepressant or it may be bipolar. This is because people who are bipolar, when they are depressed and go on an antidepressant, if they are not on a mood stabilizer could potentially cycle into a manic or hypomanic episode and very commonly that turns into what is called a mixed state.
Individuals need to be aware that if they have depressions and are not responding to treatment or if they go into a treatment and they get it and loose it, or they get their response and then they become irritable they should think bipolar.