Identifying post-exertional malaise subtypes: Differentiating physical and mental PEM manifestations, 2026, Tuzzolino et al

[Nightsong]

Abstract:
Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic illness with post-exertional malaise (PEM) as a key symptom. This study categorized participants with ME/CFS who met PEM criteria into four groups based on severity of physical and mental PEM: severe physical PEM (Physical group), severe mental PEM (Mental group), both severe (Both group), or neither severe (Neither group).

A control group was also included. The Both group exhibited the highest symptom severity, while the Neither group displayed lower scores. The Neither group experienced less disability than other ME/CFS subtypes but was significantly more disabled than Controls. Health assessments revealed that Controls had the highest functioning, followed by the Neither group, with the Both group showing greatest impairment.

These results indicate distinct PEM subtypes, emphasizing the need to recognize different manifestations of this complex symptom. Future research should include diverse control groups, longitudinal data, and biological measures to further understand PEM subtypes.

Link | PDF (J. Health Psychol., February 2026)

 

[ME/CFS Science Blog]

Very lage sample size (n = 2068) but hard to extract any new or useful info from the study.

 

[InitialConditions]

This study categorized participants with ME/CFS who met PEM criteria into four groups based on severity of physical and mental PEM: severe physical PEM (Physical group), severe mental PEM (Mental group), both severe (Both group), or neither severe (Neither group).

A control group was also included. The Both group exhibited the highest symptom severity, while the Neither group displayed lower scores. The Neither group experienced less disability than other ME/CFS subtypes but was significantly more disabled than Controls. Health assessments revealed that Controls had the highest functioning, followed by the Neither group, with the Both group showing greatest impairment.

This seems self-evident. I really don't know what the aim was here.

PDF (J. Health Psychol., February 2026, open access)

There's a paywall for me.

 

[Nightsong]

There's a paywall for me.

Fixed, sorry about that.

A few notes, then:

The study "utilized an aggregated international sample from Japan, Norway, Spain, the United Kingdom, Amsterdam, and the United States". Some were physician diagnoses; some met Fukuda, etc. Pre-COVID. PEM measurement was via the short-form DSQ-PEM; five PEM items scored by frequency & severity into a 0-100 composite. One item used as mental PEM marker ("mentally tired after the slightest effort") and one as physical PEM marker ("minimum exercise makes you physically tired"). Outcomes: symptom scores; SF-36 function/quality-of-life subscales; "energy quotient" (a pacing/energy-envelope related measure). Controls were younger than ME/CFS patients overall - they controlled for age statistically but still caution on interpretation. 2068 participants, of which 1966 self-reported having ME/CFS and 102 controls. The "both" group was by far the largest (n=1535) and the "neither" group the smallest (n=78).

I haven't been able to read through thoroughly but it doesn't seem to tell us a great deal more than we already knew.

 

[Trish]

With inclusion of Fukuda diagnoses and the DSQ scale that lists fatigability symptoms and calls them PEM, I can't take this seriously.

 

[Jonathan Edwards]

These results indicate distinct PEM subtypes,

I am not sure how they define the subtypes as 'distinct'. There is variation, but we knew that. I doubt you can draw any conclusions from differences in other features of the subsets. They are very likely to reflect ascertainment variations as much as any real differences - if indeed 'real differences' mean anything in the context of comparing different people's symptoms.