In Don’t Listen to Your Lizard Brain, I explained how we all have a reptilian brain inside us that generates primitive drives such as hunger, sexuality, and territoriality, and that we can use our neomammalian (new mammal) brain to control those drives. So why do these control mechanisms often fail in dementia?

When everything is working well, before the drives and urges produced by the reptilian brain are carried out, they are intercepted by part of the frontal lobes, which decide if and how we will act upon these feelings. For example, although we may be hungry when we see a child holding a donut that we would like, we do not take the donut from the child. Communicating through the brain’s white-matter tracts, our frontal lobes intercept this desire and, instead, prompt us to walk into the shop and purchase our own donut. Similarly, we may feel the urge to urinate halfway through a movie. Although our reptilian brain would like to urinate right there in the third row, our frontal lobes facilitate our holding our urine until we get to the bathroom.

It is the ventromedial (lower-middle) parts of the frontal lobes, just above our nose, that inhibit inappropriate responses. These regions are connected to our reptilian brain through white-matter tracts. White matter is made of long axons and dendrites—the parts of brain cells that connect with each other—covered with white myelin insulation that allows fast communication. You can think of the white matter as the wiring inside the brain that links together all the different parts. The frontal lobes also connect directly to the output parts of our brains, such as speech and the movement of our muscles, through white-matter tracts.

Some causes of dementia, such as frontotemporal dementia, affect the frontal lobes directly in the early part of the disease. In Alzheimer’s disease, chronic traumatic encephalopathy (CTE), HIV associated dementia, and several other disorders, different parts of the brain may be involved first, but the disease eventually spreads to the frontal lobes. Other causes of damage to the frontal lobes include strokes and traumatic brain injuries (TBIs). Thus, in all of these disorders, the frontal lobes that govern and control behavior may be directly damaged or destroyed.

Other causes of dementia affect the white-matter tracts in the brain that go to and from the frontal lobes. These include vascular dementia (dementia due to strokes) and multiple sclerosis. Both severe and mild TBIs—particularly when repeated—also disrupt the white matter in the brain.

Depending upon where the damage is in the brain, the individual may or may not be aware that their behavior is inappropriate. Some individuals may be unable to control their behavior but may also be horrified at what they have done. Others have no awareness that they have done something wrong.

Helping people who have these problems with self-control is difficult. Our first impulse may be to try to reason with the individual, explaining to them why they must control their behavior. This approach is rarely successful and more commonly either makes the person feel guilty about behaviors that they are unable to control or escalates the situation into a crisis.

If possible, it is best to try to plan ahead and avoid the situations in which the lack of self-control becomes a problem. For example, for the individual who will simply urinate whenever their bladder is full, take them to the bathroom every two hours (or more frequently) so that their bladder never gets full. For those who might steal food or be otherwise inappropriate in public, eat at restaurants early when they are not crowded, and request a booth in a corner away from other diners. You can also reserve through Purple Table; it is designed for those with dementia, autism, TBI, and other disorders that need special dining accommodations.

Sometimes, despite our best efforts, a person with dementia who has lost self-control may yell, strike out, throw things, take their clothes off, or do other inappropriate things. Knowing that these behaviors are due to the brain disease can help us understand what is happening, which can, in turn, help us deal with such situations with more sympathy and compassion.

In future weeks I will discuss other techniques to help individuals with dementia who have behavioral problems, including reassure, reconsider, redirect, and relax.

© Andrew E. Budson, MD, 2018, all rights reserved.

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