On November 23, Li Lei, a 29-year-old restaurant operator in Beijing, was suspected of hacking to death his parents, wife, sister and his two children. He was arrested on November 28, about 10 hours after the murders were reported.

On November 26, Wen Tieshuan, 46, used a knife to murder six villagers and seriously wounded another from five households in a tightly knit village of about 15 households in Inner Mongolia . His body was found on November 28 and police believed he committed suicide.

The official media, which usually plays down 'bad' news like murders and other crimes, has reported extensively on those mass killings because of their horrific nature, as the suspects targeted their own family members.

But most of those reports have focused on the gruesome details of the murders, and how other family members and neighbours were bewildered or devastated or angry. Only a select few national media publications like the China Youth Daily and China Daily tried to explore deeper, and underline mental health challenges for the mainland authorities.

Indeed, while the police are still investigating the motives for all four mass killings, signs have pointed to the mental state of the suspects.

In the case of Chen, the state media reported that he sought help at Kunming Psychiatric Hospital in August and was diagnosed with acute schizophrenia, but he was sent home without any follow-up from health officials.

Li's case is a bit more complicated, as he lived a comfortable life and made his first pot of gold reportedly from running a prostitution ring.

But the state media quoted police as saying that Li confessed that he had been brought up very strictly by his parents, and after he was married, his wife tried to control everything, leading him to commit the murders.

Some psychiatrists have speculated that he may have a mental illness.

But others disagreed, based on the fact that he planned the murders, and after he killed his parents, wife and sister, he waited more than one hour before finishing off his two young children.

As for Wen, his appeared to be a typical case of mental illness. According to the local police, he had showed mental problems and felt depressed in recent years, but his family was too poor to afford any proper medical care. So they turned to witch doctors for help, which only made the situation worse.

Mainly because of Chinese tradition and culture, mental health has been one of the biggest social stigmas on the mainland for centuries, and it remains so even today.

Few want to talk about it publicly, or even privately at home. But mainland authorities ignore this at their own peril, as the mental health of mainlanders has serious potential to cause social instability - something mainland leaders constantly worry about.

As a sign of how seriously mental health is taken, it is difficult to find complete and authoritative figures on the issue. But the figures quoted most often still provide a very dark picture: the number of mainlanders with mental illness is estimated at between 100 million and 170 million.

Of the 16 million who need regular medical attention, half have been diagnosed with various degrees of schizophrenia.

Every year, about 250,000 mainlanders commit suicide, accounting for a quarter of the world's total.

As a result of the deep-rooted social stigma and rising economic pressures, the number of mental patients looks set to soar in the coming years, but the government has been negligent in giving the matter the attention it needs.

The China Daily reported that there are 11 hospital beds and fewer than two psychiatrists for every 100,000 mainlanders, compared to the world average of 43 beds and four doctors.

For a start, as many mainland doctors have urged for years, the central government should push for a national law to ensure enough medical care and resources for mental health.

Second, the government should take the lead to continuously raise public awareness about the issue.

Third, the mainland leadership should spend more to beef up its social services to help those people.