Friends come and go. As our frontal lobes develop, so does our personality. This has implications for the company we choose to keep. Just because Sarah stood by your side all through high school, doesn't necessarily mean that you will have loads in common when you are both 30.

The bad news? The brain is not fully developed until we hit our mid 20's. This doesn't mean than we cannot keep our bestie from high school. Nor does it mean that we need to trade in our boyfriend when we hit 25. What it does mean is that we need to periodically sort through our friends list and perhaps make some difficult decisions.

For example, if you find that you are putting in ALL of the effort ALL of the time with certain friends, perhaps you need to ask the question; "what am I really getting out of this relationship".

Now don't get me wrong. Relationships are about give and take. Sometimes, you will be the one doing all of the giving for a friend. That's what friendship is all about right? But what happens when you get fired from your dream job, or when the love of your life leaves you for his personal trainer? Sometimes, it's through tragedy and crisis that you learn who your REAL friends are. It's during these times that your best friend in the whole world may fall off the face of the earth....and that work colleague you sometimes have lunch with, all of a sudden rises to the occasion to support and nurture you.

However, why wait for a crisis or tragedy to figure out who your real buddies are? Here are some simple tips to get you thinking. Open up your Facebook friends list....and ask yourself these questions as you work your way down the list (for some of you this may take quite a bit of time!)

1. When is the last time you saw each other? Was it awkward, or did you simply pick up where you left off? Real friends don't stress if you have not caught up for a while, so the conversation when you do finally catch up should flow freely.

2. Does she ever comment on your updates/pics? This is only really an issue if you can see they live their life online. Don't get paranoid though, just assess the facts: Is she commenting on everyone BUT you? Or does she really not comment on anyone?

3. Do you have to keep telling her your boyfriend's name? Ok, this may sound obvious but I am always amazed at how people can tolerate this one. A real friend remembers. Simple. Not the small stuff necessarily – but the big stuff. Like; your boyfriends name, where you work, how many brothers and sisters you have, whether you are a vegetarian. You get the idea?

4. Does she respect your other relationships? Does she always find something negative to say about your other friends, or worse – your boyfriend? This could be a sign of a very insecure friend, and one who has the potential to sabotage your other relationships. The message here is to be careful. By understanding her agenda, you can learn to buffer yourself from her negativity. Remember though, you should not really have to "manage" your friends......that's what work associates are for.

5. Do you have things in common? Another simple one, but one which is often overlooked. Sometimes the longevity of a friendship means that we just cannot let go. What do you talk about? Having different interests can enhance a relationship, but there needs to be some sticky stuff to hold you both together.

Now I am not suggesting you de-friend all of those "friends" who don't live up to the mark. Keep them in your life, just re-assess where you put your energy. Think about how you feel when you are with them. Do they make you feel uncomfortable, or judged? Or do they help to bring out the best in you?

In the same way our brain develops, and neural pathways are "pruned" to make way for new learning– we need to take stock of our friends and perhaps do some pruning of our own, making way for new or young relationships to grow and develop. As for our school buddy Sarah? Without the sticky stuff it can be hard to hold on. On the other hand, sometimes friends can grow with us – and it's these friendships that last a lifetime.