Akmal Shaikh was arrested in 2007
The execution of a British man convicted of drug smuggling in China has been deplored by UK officials.
Akmal Shaikh, 53 and from London, had denied any wrongdoing and his family said he was mentally ill with a condition called bipolar disorder.
What is bipolar disorder?
Bipolar Disorder, also known as manic depression, is a serious mental health problem involving extreme mood swings, usually lasting weeks or months at a time.
The moods can be euphoric highs or "manic" episodes with over-activity, racing thoughts and loss of inhibition.
At the other end is lows - bouts of deep depression and despair.
Often, bipolar involves a mix of both highs and lows, but some people only ever experience episodes of one type of mood.
How common is it?
Experts estimate that between one and two people in every hundred has bipolar disorder.
It tends to run in families but is also linked to stressful situations, which can trigger an episode of mania or depression in susceptible people, typically in their 20s.
It is thought that an imbalance of some chemicals in the brain may be a factor, and drug treatments for bipolar disorder may help to address this.
How could the diagnosis be missed?
Bipolar disorder is what doctors call a "spectrum" condition rather than a single disease. This means it affects people differently and to varying extents.
Doctors often find it hard to diagnose bipolar disorder because it causes many symptoms which can be hard to separate from normal variation.
For example, everyone experiences low mood or euphoria from time to time. The difficulty is knowing when this becomes a problem.
There are not any blood tests or scans for bipolar disorder - a diagnosis is made based on symptoms alone.
And in between episodes of highs or lows there may be gaps of weeks, months or years when mood is normal.
Some people may have only one or two episodes in their lives, rather than the most severe form where moods cycle rapidly over the years.
Also, the person may be unaware that their moods are actually part of a mental health condition. Often it is their loved-ones who first notice that there is a problem.
With treatment, some people with bipolar disorder can lead entirely normal lives.
But others will struggle with the condition and be unable to hold down a job and care for themselves.