What was once upon a time called manic depression is now referred to as bipolar affective disorder.
The treatment of bipolar depends on the phase at the time.
The main phases are:

• Mania or hypomania during which the mood is abnormally high
• Depression during which the mood is abnormally low
• Normal mood between the two extremes.
  

This is a simplistic way of looking at the illness.
Many sufferers experience mixed phases and various combinations of mood.
The length of time for each phase varies both within the individual and between sufferers.
The aim of the treatment prescribed is usually to prevent the mood swings and to tackle them if they should occur.
There is no cure for bipolar affective disorder.
The treatment is to help manage the symptoms.
A sufferer cannot be relied upon to continue with treatment and may not report accurately their symptoms.
So for any treatment to be beneficial it is helpful for the sufferer to have the support of a close friend or family member.
It is important to record the symptoms and their severity throughout the phases.
Any prescribed medications must be taken.
There is a tendency for the sufferer to decide that s/he doesn't need them any more.
It is essential to keep any and all appointments.
Again the sufferer may decide either that they are not necessary or is in a state of lethargy and cannot rouse to get ready and go.
This is where a good supporter comes in and is in effect an essential part of the treatment.
Drug treatment

• Mood stabilisers.
  These are often the first of the treatments to be prescribed.
  There is quite a variety which can be used.
  
• Antidepressants are often used in conjunction with mood stabilisers to help manage the depression although caution is needed as they can induce mania.
  
• Antipsychotics are usually required for short term use to help recovery from the extremes of the mood swings.
  
• Sedatives

Fish oils Omega-3 fatty acids seem to help as mood stabilisers in bipolar patients even though they appear to have little effect upon depressed people.
Research is going ahead to discover the ideal dose, whether it could be added to the normal medication, and if there is the possibility of overdosing.
Other treatments

• ECT or electroconvulsive therapy is considered when other forms of treatment have not had a beneficial effect or when the episodes are particular severe.
  
• Psychotherapies.
  These can be useful particularly when employed alongside medication.
  
• Psychosurgery.
  This is a treatment of last resort as it involves the cutting of neural tissue in the brain.
  
• Transcranial Magnetic Stimulation.
  This is not an intrusive treatment and so no anaesthetic is needed.
  It involves passing a magnetic current through the head to stimulate the brain.
  
• Vagal Nerve Stimulation.
  This is a minor surgical operation to insert a small pacemaker under the chest wall.
  The pacemaker is linked to the vagus nerve in the neck in order to transmit electrical pulses for stimulation.
  

There are more treatments than I have mentioned here.
There are quite a number of variations so that if one type does not agree with the sufferer due to side effects another can be substituted.
Depending upon the individual's illness, the treatments will be tailored to suit and probably include a range of those available.
However, it is important to take the advice of a fully qualified medical practitioner.