A climbing expert stabbed himself to death after developing paranoia triggered by him smoking cannabis on a trip to Amsterdam.

Liam Postlethwaite, 26, had no history of health problems but changed after he took the drug legally in the Dutch city whilst on holiday with friends.

An inquest heard he returned to the UK suffering from paranoia and became so severely ill he did not even know his own name and had to be temporarily detained in a mental hospital.

Liam Postlethwaite, 26, had no history of health problems but changed after he took the drug legally in the Dutch city whilst on holiday with friends (Picture: Liam Postlethwaite/ Cavendish Press)

In January, Liam was staying at his parents’ home in Chorley, when his mother found him dying in their back garden with self inflicted stab wounds to his chest and neck. He passed away later in his hospital despite attempts to revive him.

The tragedy comes amid growing calls for cannabis to be legalised despite medical experts repeatedly warning that the drug can cause users to develop psychotic illnesses including schizophrenia or bipolar disorder.

The drug was de-classified to Class C status in 2004 removing the threat of arrest for possession – but was reclassified to Class B again in 2009 following concerns.

Liam who studied sociology at Sheffield University worked at an outdoors pursuit centre as a rope access technician and regularly went on climbing and outdoor pursuits expeditions to keep fit.

Liam Postlethwaite seen here on his trip to Amsterdam (Picture: Liam Postlethwaite/ Cavendish Press)

But the Preston hearing was told he had been taken ill after visiting Amsterdam in 2011.

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Shortly after he returned to the UK, he had a severe medical episode which led to him being admitted to a mental hospital.

Liam’s mother Julie Postlethwaite, said in a statement: ‘Liam was a student at the University of Sheffield and he travelled to Amsterdam with friends in 2011. While there he partook in cannabis and when he came back he was paranoid and suffered from psychosis. He had never had problems before then.’

Liam’s GP Dr Neeru Garg, said: ‘He had no significant mental health issues until September 2011 when he was admitted. Then, he was prescribed Olanzapine, which is an anti-psychotic, Diazepam, and Mirtazapine, which is an anti-depressant, but by the summer of 2015 these medications stopped.

An inquest heard he returned to the UK suffering from paranoia and became so severely ill he did not even know his own name and had to be temporarily detained in a mental hospital. (Picture: Rex)

‘I understand that he suffered several episodes of anxiety and depression since then, and he started back on the Mirtazapine. When he came to see me in December, I was aware that he had quite a detailed medical health history.

‘I concluded that he had mild to moderate depression on that day and I continued him on Mirtazapine. I thought that he was managing his mental health problems well and I thought he would come the next day, which he did. In this time, he was paranoid, but he expressed no suicidal thoughts at all.’

‘I assessed him with having mild to moderate depression and he was in a safe place, at home with his parents.’

Mental health practitioner at Lancashire Care, Dr Glenn Clifton, who said: ‘I met him on January 10 and appeared to have anxiety from the outset, in particular he was fearful of with people in the mental health service – which seems to relate to his previous experiences.

‘The first thing I spotted was his anxiety. He was fearful from the outset that our intention was to put him into hospital which he was absolutely terrified of. He had started having nightmares from the experience in 2011 and he was having suicidal ideations but no intention. He was saying things like he ‘didn’t want to go on’.

Coroner James Newman recorded a verdict of suicide (Picture: Liam Postlethwaite/ Cavendish Press)

‘There was some paranoia indicated from Liam’s manner, he was worried of us bringing him into hospital. It was also due to his lack of self-worth; he felt he was a failure and worthless. But it the fears of being hospitalised were the most prevalent ones causing his anxiety.’

Coroner James Newman recorded a verdict of suicide and said: ‘It is abundantly clear that Liam had a long and documented history of mental health issues, initiated by events in 2011.

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‘I don’t find that Liam required hospitalisation leading up to his death, especially because of his fear. I think that hospitalisation could have caused more deterioration to Liam’s condition.

‘I don’t think there is significant evidence before me that this was a cry for help. I do find that not only did he inflict the wounds on himself, but he did it with the intention of taking his own life.’