Severity and correlates of brain fog in people with traumatic brain injury

Abstract

Brain fog is one symptom that has been underexplored in traumatic brain injury (TBI). We explored the cognitive and affective correlates of brain fog in people with symptomatic mild TBI (n = 15), moderate‐to‐severe TBI (n = 15), and a healthy control group (n = 16). Measures across the studies assessed “brain fog” (Mental Clutter Scale), objective cognition (Useful Field of View® and Cogstate Brief Battery®), post‐concussive symptoms (Post‐Concussion Symptom Scale), and depressive symptoms (Profile of Moods Scale). Brain fog was higher in symptomatic mild TBI and moderate‐to‐severe TBI compared with healthy controls. Greater brain fog corresponded to greater depressive symptoms in symptomatic mild TBI. Greater brain fog corresponded to poorer episodic memory and working memory in moderate‐to‐severe TBI. Brain fog appears to reflect challenges in recovery, including depressive symptoms and worse cognitive function. Screening for brain fog might be worthwhile in people with brain injuries.

Efficient assessment of brain fog and fatigue: Development of the Fatigue and Altered Cognition Scale (FACs)

“…Nevertheless, the support for the two-factor model of central fatigue and brain fog in the present study implies that prevailing assumptions about mental fatigue–and accompanying measures–might merit empirical scrutiny to improve current definitions of the construct and facilitate greater precision in measurement. Further studies of the FACs could compare it with other self-report instruments currently used to assess mental fatigue [ 17 , 39 , 64 ] and brain fog [ 12 ].…”

“…Brain fog and fatigue are also considered cardinal symptoms of post-acute sequelae of COVID-19 (PASC) [ 9 , 10 ]. Among persons with TBI, this symptom cluster is recognized as an element of post concussive syndrome [ 11 ] that persists over time [ 3 , 12 , 13 ], with debilitating effects on rehabilitation efforts [ 14 ], community reintegration [ 15 ], and clinical treatment and monitoring [ 2 , 16 ].…”

“…Peripheral fatigue refers to muscular impairment or exhaustion due to exertion; central fatigue, however, is a subjective report of an individual’s difficulty initiating and maintaining activity and attend to tasks that require sustained mental effort [ 17 ]. Brain fog is a colloquial term frequently used by patients and clinicians to describe subjective difficulties with thinking and focus, forgetfulness, lack of mental clarity, slow conversational reaction times, and occasional problems with word selection [ 2 , 12 , 18 ]. Studies using various neuropsychological instruments indicate that brain fog reflects deficits in attention, short-term and working memory, processing speed, and concentration [ 4 , 19 ].…”

Prevalence of fatigue and cognitive impairment after traumatic brain injury

“…Following TBI of all severity, a subset of individuals report "brain fog" as a symptom which includes perceived fatigue and cognitive impairment [28,29]. Individual reports of fatigue are inherently subjective, and the associated cognitive impairment may be subtle and perceptible to individuals through effects on daily life without being detected by standard neuropsychological testing [42].…”

“…Although most individuals with uncomplicated mild TBI fully recover in the first three months following injury, a subset of patients suffer long-term symptoms or disability following even mild TBI [25][26][27]. Among the most common of these lingering symptoms are fatigue and altered cognition (FAC) which is often described as "brain fog" [28,29]. Past clinical and research experience led us to define brain injury associated fatigue and altered cognition (BIAFAC) as a clinical manifestation of these symptoms that may persist following TBI or even begin to manifest after the acute recovery period [30,31].…”