Skip to main content

Cannabis inflicts long-term damage on teenage brains

Those who use the drug as teens struggle with reasoning, memory, and inhibitions in later life

  • Teenagers were asked to rate their cannabis use on a zero to five scale, zero meaning ‘never’ and five being ‘every day’
  • They were then tested in four cognitive domains: recall memory, working memory, perceptual reasoning and inhibition
  • Adolescents who used cannabis the most performed the worst on these tests 
  • Pot use in any given year was linked to impaired inhibitory control and working memory one year later

Teenagers who use cannabis are inflicting long-term damage on their brains, a new study has warned.

Researchers tracked nearly 4,000 teenagers over fours years and found clear evidence of marijuana use being linked to struggles with reasoning, memory and inhibitions later in life.

Previous studies have shown that cannabis misuse has been linked to impairments in learning, attention, and decision-making, as well as lower academic performance.

But the team, led by the University of Montreal in Canada, says its findings are the first to show the causal and lasting effects of teen pot use on cognitive development.

Researchers say marijuana use in teenagers was linked to struggles with reasoning, memory and inhibitions later on life (file image)

Researchers say marijuana use in teenagers was linked to struggles with reasoning, memory and inhibitions later on life (file image)

For the study, the team followed more than 3,800 Canadian adolescents between seventh and 10th grade for a period of four years.

Once a year, the participants rated how much they used cannabis on a zero to five scale – zero meaning ‘never’ and five being ‘every day’.

For alcohol specifically, the teens were asked to provide the typical number of drinks they have in a day.

Researchers also looked at year-over-year changes in four cognitive areas: recall memory, working memory, perceptual reasoning and inhibitions.

Tasks included being able to find a phone among a group of images, learning a pattern and being able to reproduce it 30 minutes later, and completing a sequence of puzzles with increasing difficulty.

The number of students who reported never using cannabis fell from 95.4 percent in the first year of the study to 71 percent in the last year.

Meanwhile, teens who reported using marijuana every day increased five-fold from 0.37 percent in year one to two percent in year four.

Using an advanced analytical model, the study found that teens who used cannabis more frequently performed the worst on the cognitive domain tests.

‘We were surprised that the effects of cannabis were more pronounced than the effects of alcohol,’ senior author and investigator Dr Patricia Conrod, of the department of psychiatry at the University of Montreal, told Daily Mail Online.

‘And we were surprised of the lasting effects. Even if a young person reduced their use, you could still see effects from the previous year. It was more than we expected.’

There is also a concern of teens vaping cannabis after a Centers for Disease Control and Prevention (CDC) report revealed last month e-cigarettes were being used to concel marijuana.

The report found one-third of high school students and a quarter of middle school students that had used e-cigarettes for cannabis in 2016.

A 2017 study also from the University of Montreal found that teens who smoked pot as early as 14 performed worse by age 20 on cognitive tests and dropped out of school at a much higher rate than non-smokers.

Another study from Concordia University, also located in Montreal, found that adolescents who smoked pot at age 15 or younger suffered from cognitive development and even respiratory diseases.

Dr Conrod said that there are many questions that she and her team would like to answer in future research.

‘In the context of recreational cannabis use in adults, when the brain not undergoing maturation, we want to see if they are just as vulnerable to the effects of cannabis,’ she said.

‘We also want to see if there’s a difference in sensitivity between males and females and what brain mechanisms are underlying this effect.’

When Home Invasions become commonplace, something is wrong

How many of these will it take for Sonoma County to wake up on pot farming?


Sonoma Sheriffs searching for armed home invasion robbery suspects.

 Sonoma County Sheriff’s deputies were dispatched to the 100 block on Eugenia Dr in Petaluma shortly after 3:00 AM this morning for multiple reports of armed home invasion robberies. We learned that a group of approximately nine suspects went to three different homes in the 100 and 200 blocks of Eugenia. They kicked doors in and confronted the homeowners while armed looking for mairjuana. At least one homeowner was tied up and reportedly pistol whipped.

Petaluma PD officers spotted two vehicles leaving the area and attempted traffic stops.A pursuit ensued to Novato. One vehicle, a white rental mini van stopped on SB 101 prior to the San Marin exit. Five African American men fled from the mini van fleeing to the west. A perimeter has been set and SWAT teams are searching the area for those suspects. Multiple firearms were located in and around the minivan. One of these suspects has been captured in the area and four remain outstanding.

The second vehicle was found in the Novato Costco parking lot where three suspects were taken into custody and one remains outstanding.

This information is very preliminary and it is a fluid and active event.

Prepared by: Sgt.Spencer Crum
Media Inquiries: 707-565-3941

Links related to Sonoma Cannabis

Links related to Sonoma County cannabis regulation and Just Say No to Pot Farming in Residential Neighborhoods initiative, which now includes Bennett Valley, Penngrove, Bloomfield, Two Rock and other areas.

No Pot on Purvine Home

Rural Sonoma Web

Rural Sonoma Facebook

Sonoma County Cannabis Program

Sonoma County Cannabis Rules and Ordinances

Sonoma County Policy Paper on Cultivation in Rural Residential Areas

Sonoma County Zoning Map Viewer

Petaluma Dairy Belt Area Plan

Out of state criminals here to score some pot for sale on east coast. Looks like they got one house wrong, invading a home that had no pot operation.

The Sonoma County Gazette continues coverage in their latest issue:

2016 Press Democrat, alerting to the problems of commercial pot farms in rural residential areas:

Windsor bans cannabis businesses and outdoor cultivation, citing safety concerns

Another Sonoma County city has banned pot cultivation and also dispensaries, citing burglaries and robberies. That means more speculators will be scouring county land to get rich on, at the expense of your neighborhood. It means the county needs to tighten their regs, stat.

“The largest city in northern Sonoma County is saying “no” to marijuana — no dispensaries, no cannabis businesses and no outdoor cultivation.

The Windsor Town Council last week unanimously introduced an ordinance prohibiting any type of marijuana businesses within city limits, in part to preserve warehouse space from being gobbled up by the newly legalized industry.

But town officials also want to avoid any associated problems, such as burglaries and robberies of cash-heavy marijuana businesses.

“Windsor remains primarily a family-oriented town,” said Mayor Debora Fudge, who said there has been little call from the citizenry of Windsor to adopt a more lenient attitude toward cannabis.”

Connection between cannabis and murder in Sonoma County is indisputable

9 out of the last 11 murders in Sonoma were at pot farms.

This story is powerful statement for the restrictions we are seeking.

Another pot operation, another murder.

Out of state criminals here to score some pot for sale on east coast. Looks like they got one house wrong, invading a home that had no pot operation.

The Sonoma County Gazette continues coverage in their latest issue:

2016 Press Democrat, alerting to the problems of commercial pot farms in rural residential areas:

No Pot on Purvine Update: Upcoming meeting with Supervisor Rabbitt

Notice from No Pot on Purvine – Feb 21st meeting with Supervisor Rabbitt 6PM

Hello Neighbors! We have some very important updates and an upcoming event that deserve your immediate attention.

UPCOMING EVENT:   Mark your calendars for February 21st and attend this important Meeting!

  • COMMUNITY MEETING WITH SUPERVISOR DAVID RABBIT. Attached to this email is a flyer which we are mailing to our community this weekend. It is a fact sheet containing the addresses and basic details of the five commercial cannabis applications we are most concerned about. Feel free to distribute it, and plan to bring a crowd. All are welcome and we want to pack the meeting hall!

Community Meeting with David Rabbit:

Where: Petaluma Ghost (Portuguese) Hall: 4649 Bodega Avenue, Petaluma CA 

When: Wednesday, February 21st, 2018.   6pm-7:30 PM

RSVP or Questions: Respond to this email or call our coordinator at 707-559-8563

  • The Website. Stay up-to-date on all relevant developments by checking out our website. Most notably is our new Community Map, which shows most known commercial applications in our area. Please visit WWW.NOPOTONPURVINE.COM


  • Number of applications. As if Petaluma Hills Farms (334 Purvine Road) wasn’t bad enough, the number of applications in our area has jumped from one to SIX commercial (up to 1 acre) cannabis farms within a three mile radius. The county has not indicated that they are thinking about concentration of cannabis in our area, nor are they addressing the cumulative impact of these applications on our area’s overall water, traffic, safety, etc. Our area is under siege. This is a huge problem and we are planning to address it with David Rabbit at our next meeting (see attachment).
  • Petaluma Hills Farm. Our efforts and counsel have succeeded in forcing the County to require a 72-hour test of the well on 334 Purvine Road. This is great, as this test would normally not be required and will work toward proving the water scarcity issue we face. As an added bonus, it delays their application process by three to four months (until July), affording us the time required to focus on our policy initiatives. Water User. Do not be fooled by applicants’ claims of using low-or-no water. We had a development representative run their numbers. Petaluma Hills Farm states they plan to use only 200,000 gallons on water annually. According to our newer numbers, their actual water use is closer to 2,500,000 gallons on water annually. THAT’S A LOT OF WATER.
  • Commercial Cannabis Exclusion Zone and the Cannabis Advisory Board. Given the fact that the county continues to accept applications in our area despite public outcry, we have become increasingly aware that our best chance of preventing ALL of these applications is to become a commercial cannabis exclusion zone. A cannabis exclusion zone means that the commercial cultivation of cannabis is inappropriate because it will cause significant impacts to an area’s 1) environment, 2) water resources, 3) utilities, 4) roads, 5) Fire Protection, 6) Security and 7) Residential Character. Sound familiar? This designation aligns with the community’s concerns and with the availability of resources in our area. We are working with the Cannabis Advisory Committee to develop an application process for this designation and to be classified as an exclusion zone.  
  • Neighboring City Grows: We also remind you to support our neighbors in Penngrove: A cannabis permit application on 8105 Davis Lane was approved on 2/5/18. Although their situation is a bit different than what we face here in West Petaluma, we stand with them and maintain the current Cannabis Ordinance is flawed for numerous reasons and needs to be corrected.

Final npop meeting flyer february_

Just Say No to Commercial Pot Grows in Residential Neighborhoods

Due to missteps in the original planning, and permitting process. Sonoma County is now in the position of having large scale commercial cannabis cultivation operations in residential neighborhoods.

When formulating the new rules, Sonoma County specifically intended to exclude cannabis operations from residential areas. Guess what, they didn’t, oops Do over needed.

There are currently permit applications for large scale commercial growing operations:

In Penngrove, on Davis LaneI
n Spring Hill Area, on Purvine Street
In Bloomfield Area, on Moro Street

These are only examples, there are 100’s of permit applications pending. Possibly in your neighborhood. In some cases under current rules, you would not be notified or have an opportunity to speak against it.

These are residential areas. How would you like a Pot Farm smack in the middle of your neighborhood, where your kids play and ride their bikes and where you walk your dog and where you enjoy the quiet peaceful enjoyment and rural lifestyle you likely worked your whole life to have?

Keep in mind that 8 out of the last 10 murders in Sonoma County took place at pot operations.

When asked that question at a recent meeting, the Sonoma County supervisor in attendance said plainly, no, he wouldn’t like it in his neighborhood. The Sheriff concurred.

That was at a meeting recently in Penngrove with David Rabbitt to discuss this issue and several properties that are in the works. @80 people attended and the great majority were vehemently opposed to cannabis operations in residential areas of the county.

The problem cited was not legal pot or pot growing it was pot operations in residential neighborhoods.

This paper describes the problems that Sonoma County PRMD staff highlighted to Supervisors:

“Commercial Cannabis Cultivation in Rural Residential Zones(PDF: 73 kB)”

Found here:

Issues cited:

  • Lowered property values
  • Safety. the fear of parents for their children and restricted outdoor play for children because of vicious dogs being used to protect grows
  • Noise due to massive amounts of air conditioning and generators and cooling systems for lighting
  • Massive amounts of water and electricity required, transformer blow outs
  • Heavy vehicle traffic on residential streets
  • Response considerations for fire fighters
  • Occupational hazards
  • Taxing police and fire departments, sometimes rural volunteer departments
  • The lack of right to be notified before a grower moves next door
  • The destruction of health and quality of life by pesticides and chemical fertilizers used in a residential neighborhood.

Extract: “Cannabis cultivation within residential areas can cause numerous compatibility concerns including offensive odor, security and safety concerns, proximity to sensitive land uses (i.e. schools), use of hazardous materials, unpermitted electrical and building construction causing high fire danger, light and glare, noise from generators, damage to housing stock from mold and mildew, and reduced housing stock due to single family homes being used for cannabis cultivation. Despite these compatibility issues, there are an estimated 3,000 separate cultivation operations within these districts, most of which are less than 2,000 square feet of canopy size. “

This is from the County itself and in fact the County has regulated only minimal size non-commercial pot farming in RR zoned areas (6 plants 100 Square feet).

Please write to the Sonoma County Supervisors and ask them to fix the rules to keep commercial cannabis operations in the industrial farming areas where security and lighting and other measures can be managed and where residential neighborhoods will not be put at risk.

A group has been organized in response to the proposed operation on Davis Lane:

No to Neighborhood Commercial Grows Alliance

A group has also been organized in response to a similar proposed operation on Purvine Road:

No Pot on Purvine

If you have concerns you should contact David Rabbitt’s office and time is of the essence as these permits are in processing:

Phone: (707) 565-2241

Following is From No to Neighborhood Commercial Grows Alliance, modified:

To Sonoma County Supervisors,

Here are 5 requests for your consideration:

  1. Issue an immediate moratorium on ministerial permits for commercial cannabis grows on non conforming DA parcels of less than 20 acres to enable further review, including notice to surrounding neighbors and an opportunity for them to voice their concerns and have appropriate action taken.
  2. For non conforming DA areas, revise the permit process so that they would be discretionary, not ministerial.
  3. Revise the regulations to establish a minimum buffer zone of 5,000 linear ft, between all commercial grows and any residential areas, including non conforming DA neighborhoods.
  4. Revise regulations to require that all commercial cannabis grows are subject to CEQA review.
  5. Revise regulations for commercial cannabis permits to include limitations on saturation of an area, and cumulatively consider the impacts.
  6. In the case of split zoned Properties including an RR or AR designation, the RR or AR should take precedence when applying for cannabis permits

Also please go to and join the mailing list there so you can be added to the list of concerned citizens and be kept informed