ADHD: Neurotransmitter Differences

00:01 Now let's take a look at neurotransmission in a brain without ADHD.

00:06 So take a look at the image there.

00:07 I wanted you to have kind of a starting place, and I want you to visualize this in your mind that will help you with retention of the things that we're talking about.

00:15 So you see, we have it labeled there postsynaptic.

00:18 You see the receptors there, little U-shaped on a stick.

00:21 And then you also see the actual neurotransmitters, right.

00:25 The dopamine.

00:26 We also have norepinephrine.

00:28 Now I want you to orient yourself as far as what makes a neuron postsynaptic or presynaptic. Well, just a quick review.

00:36 The neuron that's transmitting the signal is called the presynaptic neuron.

00:40 And the neuron receiving the signal is called the postsynaptic neuron.

00:45 So note that these designations are only relative to a particular synapse because most neurons are both presynaptic and postsynaptic.

00:53 But it just matters at what point you're looking, because the neuron receiving the signal is postsynaptic, and the neuron that is sending the signal is presynaptic.

01:03 Okay. So back to our drawing.

01:05 You've got your orientation.

01:06 You know what you're looking for.

01:08 We have this labeled as postsynaptic.

01:10 I want to talk about the dopamine.

01:12 Right. Do you see that there with the letters D a that's short for dopamine.

01:16 Dopamine is a catecholamine neurotransmitter.

01:19 Now it has several functions, but that includes processing rewarding experiences, memory, attention and motivation.

01:28 Now, for example, drugs like methylphenidate, they'll block the reabsorption of dopamine, which increases the amount of dopamine in the brain striatum.

01:35 This is a good thing because the brain striatum is the area that's involved in motor function and reward.

01:41 Now, there are studies that have shown that increases in dopamine in the striatum can motivate people and rodents, even to perform harder physical tasks.

01:50 So we're not going to get into detail in the drug here.

01:52 But I just wanted you to see that that's the goal.

01:55 We want to have extra dopamine available, so we don't want it to be reabsorbed.

02:00 Methylphenidate is just one example of a drug where we will go into much more detail later. But one example of a drug that blocks that reabsorption of dopamine.

02:08 So you have more available to the brain.

02:11 While I was preparing this content for you so we could study together, I found a research study by Westbrook et al.

02:18 It was really interesting because they looked at comparing people that had higher dopamine levels and lower dopamine levels in the striatum.

02:26 What they found were those with higher levels of dopamine in the striatum.

02:31 They were more focused on the benefits, and they chose the harder tasks to do.

02:36 Those with lower dopamine levels were more sensitive to what it was going to cost them to do something, or the task difficulty.

02:43 So when you're dealing with motivation, there is a lot more to learn here that higher levels of motivation can help the person have a positive perspective and look at what they can gain, rather than what it's going to cost them to get there, because they found that those with lower dopamine levels boosting dopamine can affect their mental cost benefit analysis.

03:03 So keep it in mind.

03:04 Take a look at these studies as they come out and see how they apply to your practice.

03:09 So we looked at dopamine.

03:11 Now let's take a quick look at norepinephrine because it plays an essential role in the regulation of arousal, attention, cognitive function and our stress reactions. So here we are at that postsynaptic membrane.

03:23 Again you've got this visual of the neurotransmitters and the receptors.

03:28 Now there's five types of dopamine receptors.

03:30 They're not named very cool.

03:32 They're just 12345.

03:34 Right. But Da one the dopamine one receptors are the most abundant receptors in the brain.

03:40 And with ADHD this helps with memory, attention, impulse control, locomotion.

03:46 And one of the target cells passing this message onto is the prefrontal cortex.

03:52 Now I'm listing a lot of things that are going to sound similar to you.

03:57 I'm not as concerned that you memorize D1 has these exact things, and D3 has these exact things.

04:02 In order for you to be successful, I want you to step back and just take a large overview. I'm explaining to you the nuances of what these receptors do.

04:12 I would not spend your time memorizing word for word what they do.

04:16 Just take away a big picture.

04:18 So we talked about the dopamine receptor ones right.

04:21 And we know those are the most abundant.

04:23 We listed the things that they help you with and the dopamine three receptors.

04:27 Now this is cognition impulse control attention and sleep.

04:32 All of these things we've listed on D1 and D3.

04:36 These are things that are difficult for clients with ADHD.

04:40 So continuing in our discussion of neurotransmissions, under normal conditions or non ADHD conditions, the alpha two receptors you'll see on your screen at the postsynaptic membrane.

04:51 Now the alpha two receptors, when they're activated what they do their job is to strengthen cognitive and executive functioning.

04:59 And they do this because they enhance the neuronal firing and the prefrontal cortex connections. All right.

05:06 Now I'm going to encourage you to take a pause.

05:08 We know that the research tells us if you pause and reflect and think on what you've just taken in, this will help it really stick in your brain and you'll be able to recall it when you need it.

05:19 So just hit pause on the video in just a second and think back.

05:23 What can you remember about the normal neurotransmission process? Write what those systems are.

05:29 What are key points that you can remember? And if you really want to study with me, write yourself some quick notes on that without looking at your notes.

05:37 And that will help solidify that information.

05:40 You're working with it in your working memory.

05:49 Now, when you come back, let's take a look at what this image tells us.

05:52 How is this different from the previous image we just looked at? Well, we're still in the membranes.

05:58 I see the receptors, I see the neurotransmitters.

06:01 But there's a different structure up there.

06:03 And you see that those are the dopamine transporters.

06:07 Now you see we've got it there as dat.

06:09 That's what you'll see in the literature.

06:11 Brains with ADHD have increased levels of dopamine transporters.

06:17 Okay. Well why is that a problem? It sounds like a like a cool thing.

06:20 Well, here's where the problem comes.

06:22 Dopamine transporters.

06:24 They're these key proteins, and they're the ones that regulate dopamine homeostasis in your brain. So the job or the role of the dopamine transporters is they are to move the dopamine from the extracellular space to the presynaptic neuron.

06:39 Okay. So why is that a problem.

06:40 Well that means they're sucking in all that dopamine and there's less dopamine available to the brain. Now we know dopamine does really good things in the brain.

06:49 Some researchers believe that people with ADHD have higher concentrations of dopamine transporters in their brains.

06:56 You may see this in the literature as dopamine transporter density.

07:00 And remember, since their job is to remove dopamine from the brain cells, and having higher DTD can lower the dopamine levels that are available in the brain.

07:10 Another example of the dysregulation of monoaminergic neurotransmission systems involves norepinephrine.

07:16 When you look at the image there you see net those are the epinephrine transporters.

07:22 So norepinephrine levels could be decreased just like you saw with the dopamine, especially in the prefrontal cortex.

07:30 Now, when you have less norepinephrine available in the prefrontal cortex, this can lead to negative impact on your attention and your ability to have executive functions.

07:41 Norepinephrine and dopamine are not the only neurotransmitters that are out of balance.

07:46 There's other imbalances in systems like serotonin, glutamate, and Gaba.

07:52 So your goal as a provider, if you're considering pharmacological treatment, is you want to restore homeostasis in the neurotransmitter balance and level in each of the affected areas of the brain.

08:04 I created this quick cheat sheet for you a study guide.

08:07 As you're kind of looking at these neurotransmitters you see on the left side, I have all the names listed down there for you, and on the right side you have the functions and processes that those affect.

08:17 So just keep that in your notes.

08:19 It's a great study guide.

08:20 Use it to review.

08:21 So you have that kind of solidly set in your mind.