Defining Chronic Fatigue

Interviewer: Professor, can you talk about chronic fatigue? Is that a broad definition of a number of symptoms or is it one simple disease? I mean, how do you define that?

Prof. Garth Nicolson: It's not a simple disease. It occurs in a variety of different diseases. In fact, it's the most common symptom reported by patients sick in general care.

Interviewer: Mm-hmm.

Prof. Garth Nicolson: It's present in almost every disease, and certainly every chronic illness. So by definition, it's fatigue that has lasted for six months or more; is not refreshed by sleep. And it's unrelenting in general . . . 

Interviewer: Mm-hmm.

Prof. Garth Nicolson: . . . unrelenting fatigue.

Interviewer: Is that the only symptom, or are there other things that go along with that?

Prof. Garth Nicolson: Well, generally there are other things that go along with that. And there are other reasons for it. We're concentrating on cellular energy because, of course, cellular energy provides the means by which you escape fatigue.

Interviewer: Mm. Why is chronic fatigue such a big problem?

Prof. Garth Nicolson: Well as I mentioned, it's the number one complaint in all patients seeking general medical care. It's also a prominent symptom in a variety of different diseases.

Interviewer: Mm-hmm.

Prof. Garth Nicolson: Particularly, every chronic disease involves disease.

Interviewer: Mm-hmm.

Prof. Garth Nicolson: Fatigue is also present in, for example, cancer, heart disease, and some of the main diseases that strike mankind . . . 

Interviewer: Mm.

Prof. Garth Nicolson: . . . involve fatigue.

Interviewer: Can you describe what's happening with somebody at the cellular level that has chronic fatigue.

Prof. Garth Nicolson: At the cellular level, fatigue is generally the lack of energy, cellular energy, which is primarily provided by an organelle inside the cell, called the mitochondria. And we have several mitochondria inside our cells that provide high energy molecules like ATP that are necessary for every function. Metabolic activity and things that cells do in general . . . 

Interviewer: Mm-hmm.

Prof. Garth Nicolson: . . . require energy. That energy has to be provided. And in general, it's provided by oxidative phosphorylation. So we take in oxygen, for example, and we burn carbohydrates and lipids and proteins, and we convert that into energy. And it's converted into high energy molecules which then can drive a variety of different functions inside cells.

Interviewer: So what's happening when that's not working? Why is that in someone when it's not working?

Prof. Garth Nicolson: When people have chronic fatigue, one of the primary problems is the mitochondria are not functioning at peak levels.

Interviewer: Mm-hmm.

Prof. Garth Nicolson: and this happens, by the way, during aging. So it's not necessarily a disease problem. When people age their mitochondrial function goes down. When they have disease, their mitochondrial function goes down. If they get an infection, their mitochondrial function goes down. So it can happen in a variety of different situations. But in general, it's loss of mitochondrial function that promotes fatigue. So you don't have the high energy molecules necessary for all the cellular functions that take place . . . 

Interviewer: Mm-hmm.

Prof. Garth Nicolson: . . . inside us.