Cognition and multiple sclerosis: A historical analysis of medical perceptions*

Abstract

The earliest descriptions of multiple sclerosis (MS) rarely distinguished cognitive impairment from the general category of "mental symptoms", which also encompassed a broad range of affective disorders. Case-study methods led to disputes about the extent and nature of these symptoms, exacerbated by different national medical traditions. Appropriate scientific methods were only used to investigate cognitive performance in a modest number of studies up to the 1960s, and it was being argued as late as the mid 1970s that affective processes rather than cognitive processes were the key to understanding the psychological aspects of MS. However, the early 1980s, saw major developments in test procedures for the detection of subtle and selective cognitive changes, in the use of brain imaging techniques, and in collaboration between neurologists and neuropsychologists. Pressure to use research findings to improve patients' daily lives suggests a need to reconsider the connection between affective and cognitive processes in MS.

How the Conflict between American Psychiatry and Neurology Delayed the Appreciation of Cognitive Dysfunction in Multiple Sclerosis

“…With the advent of U.S. psychology in the 1920s, and its emphasis on mental activity and cognitive assessment, researchers began to seriously examine cognition in MS, especially regarding intellectual impairment (Richardson et al 1997). In 1919, Jeliffe noted mental symptoms in MS "are much more frequent than is usually taught; (and include) difficulty in thinking, spasmodic intermittent alternations in the capacity for attention and concentration, lapses of memory" (p. 517).…”

“…Diagnostic criteria for the disease were adjusted to reflect the critical role of MRI scans in this challenging process (McDonald et al 2001;Polman et al 2005). Many studies have reported total lesion burden on MRI predicts cognitive impairment as assessed neuropsychologically (Arnett et al 1994;Comi et al 1993;Patti et al 1995;Richardson et al 1997;Ryan et al 1996), and in general, cognitive loss becomes more severe as plaque burden and cerebral atrophy advance (Filley 2001). Some investigators proposed a threshold white matter disease burden of approximately 30 cm2 as the cutoff area above which cognitive impairment can be expected (Rao et al 1989;Swirsky-Sacchetti et al 1992).…”

“…Given problematic patient selection procedures and assessment of cognitive status, their results should have been questioned, instead, the conclusions proved exceptionally enduring. Trusted reputations of the investigators may have perpetuated the myth that cognition was not relevant to MS (Richardson et al 1997).…”

“…As Charcot noted, deficits such as these may be so disabling as to lead to dementia, a syndrome now known as white matter dementia (Filley et al 1988;Filley 2001). Many questions remain, but considerable effort is being devoted to refining the origin, natural history, and treatment of cognitive dysfunction in patients with MS. Richardson et al (1997) conducted a review clarifying why cognitive deficits were not fully appreciated as part of MS for a significant part of its history and why they were eventually included within descriptions of the disease. They concluded that cognitive deficits in MS were not acknowledged because medical traditions with opposing viewpoints created resistance to new ideas, and with the advent of the cognitive revolution, MRI technology, growth in neuropsychology, cognitive psychology, as well as advancement in research methodology and statistics, it became difficult to deny the connection between cognition and MS.…”

“…deficits (Richardson et al 1997). Rather than detail the range and frequency of cognitive symptoms under various conditions, such as early versus late disease, Charcot's contribution to the discussion, in hindsight, was to increase awareness of the potential for cognitive compromise in this disease when cerebral involvement was present.…”