Teenagers who smoke cannabis damage their brains for LIFE and may be more likely to develop schizophrenia

Mouse study only so even if the damage is as described, quantifying it is a large problem.  The damage in people could be real but maybe trivial

Teenagers who regularly smoke cannabis suffer long lasting brain damage and are in much greater danger of developing schizophrenia.
American researchers say the drug is particularly dangerous for a group of people who have a genetic susceptibility to the mental health disorder - and it could be the trigger for it.

Asaf Keller, of the University of Maryland School of Medicine, said the results highlight the dangers of teenagers smoking cannabis during their formative years. The study found that even short-term exposure to cannabis impaired brain activity, with the damage continuing into adulthood

The study, published in the journal Neuropsychopharmacology, exposed young mice to the active ingredient in marijuana for 20 days.  It found that their brain activity was impaired, with the damage continuing into adulthood.

The past 20 years has seen major controversy about the long-term effects of marijuana, with experts divided over its long-term effects on teenagers.

Previous research has shown that children who started using marijuana before the age of 16 are at greater risk of permanent brain damage, and have a significantly higher incidence of psychiatric disorders.

‘Adolescence is the critical period during which marijuana use can be damaging,’ said the study's lead author, Sylvina Mullins Raver, a PhD candidate at the University of Maryland School of Medicine.
‘We wanted to identify the biological underpinnings and determine whether there is a real, permanent health risk to marijuana use.’

The scientists began by examining cortical oscillations in mice. Cortical oscillations are patterns of the activity of neurons in the brain and are believed to underlie the brain's various functions.  These oscillations are very abnormal in schizophrenia and in other psychiatric disorders.

The scientists exposed young mice to very low doses of the active ingredient in marijuana for 20 days, and then allowed them to return to their siblings and develop normally.

‘In the adult mice exposed to marijuana ingredients in adolescence, we found that cortical oscillations were grossly altered, and they exhibited impaired cognitive abilities,’ said Raver.

‘We also found impaired cognitive behavioural performance in those mice. The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood.’

The scientists repeated the experiment, this time giving marijuana to adult mice that had never been exposed to the drug before.

Their cortical oscillations and ability to perform cognitive tasks remained normal, indicating that it was only drug exposure during the critical teenage years that impaired brain activity.

‘We found that the frontal cortex is much more affected by the drugs during adolescence,’ said Keller.  'This is the area of the brain controls executive functions such as planning and impulse control. It is also the area most affected in schizophrenia.’

Keller now wants to know whether the effects can be reversed. ‘We are hoping we will learn more about schizophrenia and other psychiatric disorders, which are complicated conditions,’ he said.

‘These cognitive symptoms are not affected by medication, but they might be affected by controlling these cortical oscillations.’

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Blood pressure drugs may boost brainpower: Side effect of medicines slows dementia patients' mental decline

Very preliminary findings

Doctors have long recognised that taking blood pressure drugs may slow the onset of Alzheimer’s.

Now researchers have uncovered the first evidence that the drugs, called ACE inhibitors, may actually boost brainpower.

Those with high blood pressure are more at risk of developing Alzheimer’s and similar diseases, but the study found their memory and thinking skills were protected by the drugs they were taking.

ACE inhibitors – whose names  include ramipril, captopril and perindopril – have become increasingly popular in the past ten years, particularly for younger patients.

Researchers in Ireland and Canada investigated drugs which target a specific biochemical pathway called the renin angiotensin system – a hormone system which is thought to affect the development of Alzheimer’s.

The study compared the rate of cognitive decline in 361 patients diagnosed with Alzheimer’s disease, vascular dementia (caused by problems in blood supply to the brain), or a mix of both. Of that group, 85 were already taking ACE inhibitors; the rest were not.

The researchers also analysed the impact on 30 patients, with an average age of 77 years, who were taking the drugs for the first time.

They were assessed over six months, using the Standardised Mini Mental State Examination or the Quick Mild Cognitive Impairment tests.

Those taking ACE inhibitors experienced marginally slower rates of cognitive decline than those who were not, found the study in the journal BMJ Open.

Meanwhile, the brainpower of those patients who had been newly prescribed ACE inhibitors actually improved, the experts from University College Cork in Ireland and McMaster University in Ontario, Canada found.

It is the first evidence to suggest these drugs may not only halt cognitive decline, but may actually improve brainpower.

The researchers said: ‘Although the differences were small and of uncertain clinical significance, if sustained over years, compounding effects may well have significant clinical benefits.’

They warn that ACE inhibitors are harmful to some patients, so if larger studies confirm they work well in dementia, it may be only certain people with high blood pressure who stand to benefit.

Previous studies have linked other forms of blood pressure medication with anti-dementia benefits.

Dr James Pickett of the Alzheimer’s Society said: ‘Any drug which halts cognitive decline is potentially exciting because it has the ability to radically improve quality of life.’

But Dr Simon Ridley of Alzheimer’s Research UK said: ‘This is a short study with a small number of participants. It is unclear if the [improvement] could be due to the control of blood pressure, a different effect of the drugs or another factor.’

Among the most widely used ACE inhibitors are perindopril (also known as Coversyl), ramipril (Tritace), captopril (Capoten), trandolapril (Gopten), fosinopril (Staril), lisinopril (Zestril and prinivil).

They work by stopping the  body from creating the hormone angiotensin II. This has a variety  of effects but essentially relaxes blood vessels and helps reduce the amount of water re-absorbed by  the kidneys – helping decrease blood pressure.

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