HSBC has sacked employees who made an "abhorrent" video in which they pretended to be Islamic State militants carrying out a beheading.

The video was posted online and shows a man dressed in an orange jumpsuit, while five other men in black stand around him - one holding a fake knife.

The Sun said the employees were members of the bank's legal division in Birmingham on a team building exercise.

The bank said it did not tolerate "inappropriate behaviour".

"As soon as the Sun brought this video to our attention we took the decision to sack the individuals involved," the bank said.

"This is an abhorrent video and HSBC would like to apologise for any offence caused."

The bank did not specify how many people had been sacked.

The newspaper has posted an eight-second clip of the video on its website in which one man shouts "Allahu Akbar" - Arabic for "god is great" - while others laugh.

Cognitive Behavioural Therapy (CBT) has many advantages for treating depression. Among them, the fact that it's easy to standardise, it's intuitive and it can deliver results relatively quickly (think weeks, not years as some other therapies demand). For many people with depression, it's also far more acceptable than the prospect of taking mind-altering drugs. But now the bad news: CBT's efficacy seems to be declining.

That's the suggestion of a new meta-analysis (pdf) that's looked at outcome data from 70 studies published between 1977 and 2014 and involving more than 2,426 people diagnosed with depression (uni polar depression, not bipolar). Across studies, 31 per cent of the participants were male; the average age of participants was 41.

To allow comparison over time, Tom Johnsen and Oddgeir Friborg chose to focus only on studies that used the Beck Depression Inventory or the Hamilton Depression Rating Scale – two popular measures that involve the patient or therapist, respectively, providing scores of the patient's depression. Looking at the effect of CBT on adults' depression scores using either of these scales (i.e. by comparing scores pre vs. post therapy), the researchers found a linear and steady reduction in the therapy's apparent efficacy over time. Simply put, CBT doesn't seem to be helping reduce depression symptoms as much today as it used to when it was first developed in the 1970s.

This main finding held true even when the researchers focused on certain types of study – such as analysing only those that involved a control group. The finding can't be explained by a general change in people's ability to recover from depression: there was no comparable decline in change scores among participants in control groups who didn't receive CBT. Nor is it the case that recent studies, more than older studies, tended to involve depressed patients who also had other mental health problems (in fact the opposite is true).

Changes in therapist competence (e.g. their level of training) also can't explain the declining trend in CBT efficacy. And to debunk one last potential explanation, the researchers point out that the decline in efficacy was actually steeper for trials involving manualised CBT – so it's not the case that more modern trials have simply become sloppier in their CBT methods.

So, why is CBT apparently losing it's power to help people with depression? Johnsen and Friborg can only speculate. One suggestion they have is that CBT is somehow losing its placebo effect over time:

    In the initial phase of the cognitive era, CBT was frequently portrayed as the gold standard for the treatment of many disorders. In recent times, however, an increasing number of studies ... have not found this method to be superior to other techniques. Coupled with the increasing availability of such information to the public, including the Internet, it is not inconceivable that patients’ hope and faith in the efficacy of CBT has decreased somewhat, in recent decades. Moreover, whether widespread knowledge of the present meta-analysis results might worsen the situation, remains an open question."

Schools are being offered new software that helps teachers spy on pupils' potentially extremist online activity.

It alerts teachers if pupils use specific terrorism-related terms or phrases or visit extremist websites on school computers, laptops or tablets.

Teachers are encouraged to look for a pattern of behaviour rather than raise the alarm after a single warning.

Since February, the Counter Terrorism and Security Act has required schools to prevent pupils becoming radicalised.

But the National Union of Teachers has expressed fears this could lead to debate on contentious issues being shut down.

It also said some teachers feared they could be prosecuted if they dealt with a situation in the wrong way.

The issue was highlighted by the case of three London schoolgirls who travelled to Syria in February and are believed to be in the city of Raqqa, a stronghold of Islamic State.

Their families later complained that police, the school and the local authority had failed to pass on information they said could have prevented the girls leaving.

Jonathan Russell, political liaison officer at Quilliam Foundation, which developed the software, said: "The internet has made it easy for young people to access extreme or radical material.

"While measures such as the UK government's Prevent Strategy already existed, it's now clear that more needs to be done to counter radicalisation early on.

"Protecting young people from the dangers of radicalisation requires positive online counter-extremism, and empowering teachers with technology like Impero's keyword library is an important part of this process."

Sally-Ann Griffiths, of Impero Software, which designed the program, said: "With a widely reported increase in the number of children being radicalised, it's vital that schools put measures in place to prevent pupils coming to harm online.

"By defining terms such as 'yodo', a phrase used by jihadist sympathisers meaning 'you only die once', the glossary gives teachers, who are part of the solution to the problem, the tools they need to identify, intervene and safeguard at-risk pupils."