Overcoming Internet Addiction For Dummies. David N. Greenfield

this is an oversimplified explanation, but suffice it to say that the power of the human brain derives not only from its constituent lobes and functional centers, but from how they all interconnect and communicate.

      Neurotransmitters are the chemicals that allow neurons to communicate and connect with each other. Many neurotransmitters are in the central and peripheral nervous system, the major ones being dopamine, serotonin, norepinephrine, GABA, acetylcholine, glycine, and glutamate. The three that we frequently deal with in psychiatry, psychopharmacology, and addiction medicine are dopamine, serotonin, and norepinephrine, although we have recently begun targeting and integrating some of the other neurotransmitters as well.

      © John Wiley & Sons, Inc.

      FIGURE 2-3: A neuron firing.

The way in which neurons connect is quite amazing and is a combination of electricity and chemistry. Without getting into the weeds here, each neuron is typed to a specific neurotransmitter, and for the most part only uses that neurotransmitter for firing its respective neurons. Here’s how it works (see Figure 2-3):

       An electrical signal moves through an axon (the electrical cable I mention earlier), and this signal travelling along the biological wire is called propagation. Some unique aspects of the axon help facilitate this propagation and make it as fast and efficient as possible; a special superfast coating exists along the axon called myelin, and this myelin sheath allows for a faster electrical transmission.Nature also uses other tricks to keep nerve signals moving along. Many axons also have built-in speed bumps called nodes of Ranvier (shown in Figure 2-2), which essentially allow the electrical signal to jump across the tips of these nodes to speed up transmission. This is in part what allows our nervous system to operate at lighting speed, and this leaping is called saltatory conduction.

       That electrical signal comes barreling down the axon to a gate (actually, a gap) called a synapse. When it reaches the synapse (or gap), a seemingly magical thing occurs: The electrical signal is converted to a chemical one by facilitating an action potential that commands the presynaptic membrane (one end of the axon) to release its store of the associated neurotransmitter. This transmitter is then taken up (the term is uptake) into the post-synaptic receptor and then converted back to an electrical signal; this nerve conduction process occurs millions of times a second. (See Figure 2-4.)

       The leftover neurotransmitter that is not taken up is then either biodegraded (absorbed) or taken back up (reuptake) by the pre-synaptic receptor for later use.

      © John Wiley & Sons, Inc.

      FIGURE 2-4: Inside a synapse.

      

Antidepressants, particularly selective serotonin reuptake inhibitors (SSRI), prevent the reuptake of serotonin. This allows more serotonin to be available, which, in theory, can elevate mood and help alleviate depression.

The king of neurotransmitters related to addiction is dopamine. Although other neurotransmitters are undoubtedly involved with addiction, dopamine constitutes the lion’s share of the pleasure drive we see in addiction. Internet screen use elevates dopamine reception at the post-synaptic receptor in the nucleus accumbens, and over time there is an up-regulation of these post-synaptic receptors to manage the increasing level of dopamine present in this area of the brain. See the nearby sidebar “The role of up-regulation and down-regulation in addiction” for details.

THE ROLE OF UP-REGULATION AND DOWN-REGULATION IN ADDICTION

      As a person increases dopamine in the limbic reward system of their brain, this translates into increased pleasure; not surprisingly, pleasurable behaviors tend to be repeated, especially when there is an unpredictable or variable element to the pleasurable hit. Biologically, this is where up-regulation and down-regulation come in.

      As the nucleus accumbens is hit with signals that increase dopamine, the post-synaptic receptor binding sites (call them Pacmen, as in the video game) first begin to up-regulate (become more plentiful) and are constantly occupied by dopamine. The receptor sites then slowly respond less to the same levels of dopamine. This is called down-regulation (or desensitization), and it makes sense that this would produce tolerance, meaning that you would need more stimulation to get the same effect, which I discuss earlier in this chapter. This is because to keep those neurons firing, they now need more stimulation, and this increase produces down-regulation or desensitization. With technology and screen addiction, this might mean more intense or stimulating content, faster Internet speeds, quicker access, more frequent use, or longer use times — all of which we tend to see with Internet and technology addiction.

      All this can lead to the development of reward deficiency syndrome, which occurs when the reward center acclimates to that intense level of stimulation and only receives a significant dopamine hit when engaging in excessive or intensive screen time; by comparison, everything else looks and feels flat and uninteresting. This is a very common complaint from parents and family members where their addict loved one no longer takes pleasure in any previously pleasurable behaviors. This is essentially an example of down-regulation, in that when those hungry Pacmen are consistently fed, they need more stimulation to get the same effect. Real-time living no longer provides the stimulation necessary to fire those neurons in the nucleus accumbens in order to help a person feel good or to experience pleasure from normal living. Those receptors become used to being occupied, and they become accustomed to the resulting increased dopamine levels. Unless the person is continuously excited by repeated Internet or screen use, they experience a biological deficiency in the form of psychological symptoms such as boredom and feeling “blah,” anxious, irritable, unmotivated, or even depressed.

      This is a tough place to be because there is a high likelihood of relapse at this time; we generally want to feel good, and the quickest way to feel good is to engage in the behavior that we know will get that result quickly. It’s also a difficult time because the motivation to engage in other real-time behaviors that could eventually prove to be fun and stimulating (dopaminergic) is very low, and it also takes some time for the receptors to re-regulate. This creates a challenging period for the addict and their family, as it occurs between the discontinuation of the old behavior and its resulting neurochemical effects, and engagement in the new behavior, with its more balanced neurochemical state. This new desired state of up-regulation is sort of the opposite of down-regulation on a biological level, and involves getting the dopamine receptors in the nucleus accumbens to re-sensitize to more normal levels of real-life stimulation. The Internet is very stimulating, and things like video games, YouTube, pornography, or even social media can retrain our nervous system to get used to that stimulation.

Recognizing the Mind and Body Aspects of Addiction

      

So, what does all this talk of evolution earlier in this chapter have to do with addiction, anyway? Well, the brain’s ability to use dopamine to ensure certain survival behaviors can also be stimulated by other pleasurable behaviors. It seems that drugs, alcohol, sex, food, gambling, the Internet, pornography, video gaming, and even social media all elevate our dopamine levels. Addiction is in part related to becoming habitually dependent on this elevation of dopamine; this, along with various psychological, social, and behavioral factors, produces