Understanding Cognitive Fluctuations: What Do They Entail?
Cognitive difficulties are a common symptom of Parkinson’s disease and can be very challenging both for people with PD and their care partners. Typically, these changes are noticed slowly over time as the person with PD develops more difficulty with tasks and activities.
Sometimes, however, a person with PD may demonstrate a relatively sudden change in their thinking and attention which then resolves back to their original baseline.
Concerned care partners have described these cognitive episodes like this:
- “At times he responds very clearly when I ask him a question, but at other times, I can’t get him to respond to my questions at all. He is awake but just stares and seems not to hear me.”
- “It started off being several times a day. I would notice a blank stare that would last a minute or two. Now these episodes are more frequent and last much longer – up to one hour or more. Yesterday, one happened and when I shook him, he came out of it.”
- “He goes into these comatose states where for hours we can’t get him to wake up or respond.”
- “I tried to wake my husband up at 8 a.m. He was in a nonresponsive sleep (like a coma) for hours. My daughter and I talked to him that whole time with no response. When he did come out of it, he just popped his eyes open, as if nothing had happened.”
If this type of episode is familiar to you, the first thing to do is to discuss the diagnostic possibilities with the person with PD’s neurologist. The neurologist may want to check for seizures, transient ischemic attack (or TIA, which is a temporary change in neurologic function due to an interruption in blood flow in the brain), or fluctuating blood pressure.
The doctor may order an EEG to check for seizure, an MRI to check for a stroke, or an image of the blood vessels of the brain to make sure that blood flow to the brain is healthy. The neurologist may also ask you to see if the person with PD’s blood pressure varies significantly between lying down and sitting up or standing to determine whether drops in blood pressure may be contributing to the alterations in attention.
However, if none of these tests point to a cause, the likely possibility is that the episodes are cognitive fluctuations, a well-recognized and common, but poorly understood symptom in which there is a sudden, significant, and reversible alteration of cognitive abilities, often accompanied by a disturbance in the level of alertness.
The fluctuations can vary widely in how “out of it” the person with PD seems. For some, the change may be a slowness to respond or an increased blankness to their demeanor. Care partners often describe the episodes as “staring spells”. For others, the person may be impossible to arouse. The fluctuations may also vary widely in how long they last – from seconds to many hours. Some care partners describe that fluctuations can take days or even weeks to resolve.
The person experiencing the cognitive fluctuation may or may not be aware that it is happening. If they are aware, there is variability in how it is experienced. Some are not bothered when it occurs, while others may find it disconcerting or upsetting.
How to differentiate cognitive fluctuations from other conditions
Cognitive fluctuations can be very scary for the care partner and family members, especially when the episodes last for a long time, yet they are not particularly harmful. As described above, the neurologist can help to determine if what the person is experiencing is a cognitive fluctuation, or another reversible neurologic condition. Certain features of the episode can help make this distinction. For example, cognitive fluctuations can often be interrupted by shaking the person or calling their name, which does not occur in seizure or TIA.
In addition, cognitive fluctuations are not accompanied by other neurologic deficits, such as weakness in the face or a limb, sensory changes, or visual loss, whereas these types of changes are characteristic of a TIA. Blood pressure fluctuations are usually triggered by changes in head position (e.g., going from lying down to sitting or to standing) which is not the case for cognitive fluctuations.
Cognitive fluctuations and dementia
Cognitive fluctuations are typically seen in people who have dementia (which is defined as cognitive problems that interfere with daily functioning.) They can be seen in people with dementias of all types including Alzheimer’s disease and vascular dementia but are more commonly seen and more characteristic of the dementias associated with Lewy bodies.
As a reminder, Lewy bodies are abnormal accumulations of the protein alpha-synuclein which are found in nerve cells in various parts of the brain in Parkinson’s disease and related disorders. Lewy bodies are thought to cause degeneration of the nerves in which they are found and therefore contribute to a variety of Parkinson’s symptoms. For example, Lewy bodies that are found in the substantia nigra contribute to the motor symptoms of PD including slowness, stiffness, and tremor. When Lewy bodies are present in the thinking parts of the brain, they contribute to cognitive difficulties which when more widespread, can culminate in Parkinson’s disease dementia (PDD) or in a related disorder called dementia with Lewy bodies (DLB).
Cognitive fluctuations tend to occur when the brain is more widely affected by the presence of Lewy bodies.
Why do cognitive fluctuations occur?
Why cognitive fluctuations happen is very poorly understood. One theory is that fluctuations occur when the brain circuitry responsible for transitioning from sleep to attentiveness is not working properly and the person with PD goes from one state to another in an unregulated manner. Since there are multiple brain regions and pathways that work together to regulate whether a person is awake or asleep, several brain regions may need to be affected for cognitive fluctuations to occur.
Unfortunately, with our limited understanding of why these episodes occur, there are no specific treatments that have been identified to help decrease these episodes. However, understanding that these episodes are not dangerous, are temporary, and are experienced by many others, can be reassuring to care partners who understandably often find these bouts very scary to witness.
What should you do if you notice cognitive fluctuations?
As always, keep good track of what’s happening and keep your neurologist informed about the number, length, and characteristics of the episodes, especially if any of these features change, so that he/she can make sure that other issues are not developing and/or contributing to the episodes. Never hesitate to bring up a concern or new symptom with the health care team.
Tips and takeaways
- Cognitive fluctuations refer to sudden and reversible changes in a person’s level of alertness that can be a symptom of Parkinson’s disease dementia or dementia with Lewy bodies.
- Care partners should keep track of these episodes so they can relay helpful information to the healthcare team.
- In most cases, cognitive fluctuations can be distinguished from seizures, blood pressure fluctuations, and transient ischemic attacks. It is good to rule out other health conditions that may need medical attention.
- Cognitive fluctuations may be due to disrupted brain circuitry that transitions a person from being asleep to being alert.
- Unfortunately, treatments are not currently available, but care partners may take comfort in knowing that the episodes are not dangerous and typically resolve on their own.