Former athletes who sustained concussions during early adulthood experienced cognitive and motor decline later in life, according to a study in the January online Brain. Athletes who had experienced sports concussions more than 30 years prior to testing had “significant response inhibition and episodic memory decline measurable on both event-related potentials and classic neuropsychologic tests particularly sensitive to mild cognitive impairment and early-onset Alzheimer’s disease,” reported Louis De Beaumont and colleagues.
The investigators examined 19 healthy former athletes in late adulthood (mean age, 61) who had sustained their last sports-related concussion in early adulthood (mean age, 26) and compared them with a group of 21 healthy former athletes who had no history of concussion (mean age, 59). Cognitive mental status and neuropsychologic assessments, such as the Mini-Mental State Examination (MMSE) and the Rey-Osterrieth Complex Figure Test (RCFT), were administered. Participants also performed a modified version of the Eriksen flanker task. In addition, a three-tone auditory oddball paradigm was used to evoke P3a and P3b brain responses. To assess motor cortex excitability, the researchers used four transcranial magnetic stimulation paradigms—resting threshold, paired-pulse intracortical inhibition and intracortical facilitation, input/output curve, and cortical silent period.
Cognitive Mental Status and Neuropsychologic Findings
Although both the concussion and nonconcussion groups scored within the normal range on the MMSE, significant differences were found in other areas. The concussion group scored lower in immediate and delayed recall on the RCFT. Both groups had similar mean reaction time and response accuracy to the target stimulus of the auditory oddball task, but the concussion group showed significant p3a latency delays and amplitude reductions, compared with the control group.
“While none of the two-tailed Pearson correlations computed between P3a amplitude/latency and the RCFT conditions revealed to be significant, the amplitude of the P3a component and accuracy scores of former athletes with concussions at the incongruent condition of the Flanker task was highly significant,” said Mr. De Beaumont, a graduate student at the Center of Research in Neuropsychology and Cognition at the University of Montreal, and colleagues.
The P3a amplitude of those with a history of sports concussion was strongly associated with the flanker interference effect. Subjects with concussion also had a substantially prolonged cortical silent period and reduced movement velocity. “This significant group difference is not surprising considering that former athletes with concussion took more time, on average, to complete a pronation-supination cycle that exhibited reduced angular displacement,” the authors noted. “None of the motor or cognitive measures that were found to be significantly altered in former athletes with concussions correlated either with the number of concussions sustained, the time elapsed since the last concussion, or the severity of concussions sustained….
“The finding that the P3, the cortical silent period, as well as neuropsychologic and motor indices were altered more than three decades postconcussion provides evidence for the chronicity of cognitive and motor system changes consecutive to sports concussion,” Mr. De Beaumont and his group concluded. These findings are “fairly robust, bearing in mind that they were found in a group of highly educated, former concussed athletes who maintained an active lifestyle and presented with no medical condition requiring daily medication. This is in sharp contrast with most neuropsychologic studies of sports concussion conducted with young athletes that typically show return-to-baseline performance levels within a few weeks postinjury.”
—Laura Sassano