Niklas Lehto

Neurochemical Aftermath of Repetitive Mild Traumatic Brain Injury

Importance Evidence is accumulating that repeated mild traumatic brain injury (mTBI) incidents can lead to persistent, long-term debilitating symptoms and in some cases a progressive neurodegenerative condition referred to as chronic traumatic encephalopathy. However, to our knowledge, there are no objective tools to examine to which degree persistent symptoms after mTBI are caused by neuronal injury. Objective To determine whether persistent symptoms after mTBI are associated with brain injury as evaluated by cerebrospinal fluid biochemical markers for axonal damage and other aspects of central nervous system injury. Design, Settings, and Participants A multicenter cross-sectional study involving professional Swedish ice hockey players who have had repeated mTBI, had postconcussion symptoms for more than 3 months, and fulfilled the criteria for postconcussion syndrome (PCS) according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) matched with neurologically healthy control individuals. The participants were enrolled between January 2014 and February 2016. The players were also assessed with Rivermead Post Concussion Symptoms Questionnaire and magnetic resonance imaging. Main Outcomes and Measures Neurofilament light protein, total tau, glial fibrillary acidic protein, amyloid β, phosphorylated tau, and neurogranin concentrations in cerebrospinal fluid. Results A total of 31 participants (16 men with PCS; median age, 31 years; range, 22-53 years; and 15 control individuals [11 men and 4 women]; median age, 25 years; range, 21-35 years) were assessed. Of 16 players with PCS, 9 had PCS symptoms for more than 1 year, while the remaining 7 returned to play within a year. Neurofilament light proteins were significantly increased in players with PCS for more than 1 year (median, 410 pg/mL; range, 230-1440 pg/mL) compared with players whose PCS resolved within 1 year (median, 210 pg/mL; range, 140-460 pg/mL) as well as control individuals (median 238 pg/mL, range 128-526 pg/mL; P = .04 and P = .02, respectively). Furthermore, neurofilament light protein concentrations correlated with Rivermead Post Concussion Symptoms Questionnaire scores and lifetime concussion events (ρ = 0.58, P = .02 and ρ = 0.52, P = .04, respectively). Overall, players with PCS had significantly lower cerebrospinal fluid amyloid-β levels compared with control individuals (median, 1094 pg/mL; range, 845-1305 pg/mL; P = .05). Conclusions and Relevance Increased cerebrospinal fluid neurofilament light proteins and reduced amyloid β were observed in patients with PCS, suggestive of axonal white matter injury and amyloid deposition. Measurement of these biomarkers may be an objective tool to assess the degree of central nervous system injury in individuals with PCS and to distinguish individuals who are at risk of developing chronic traumatic encephalopathy.

Effects of age on marathon finishing time among male amateur runners in Stockholm Marathon 1979–2014

Purpose The purpose of the present study was to investigate the age-related changes in the endurance performance among male amateur marathon runners. Methods Subjects were taken from the 36 Stockholm Marathons held from 1979 through 2014, and age and finishing time were analyzed for a total of 312,342 male runners. Results The relation was found to be a second-order polynomial, t = a + bx + cx2, which models 99.7% of the variation in the average running time t as a function of age x. The model shows that the marathon performance of the average runner improves up to age 34.3 ± 2.6 years, thereafter, the performance starts to decline. A quantification of the ages influence on running time shows that it accounts for 4.5% of the total variance seen in the performance data. Conclusion These outcomes indicate that the effect of age on performance in endurance running events is clearly measurable, quantifiable, and possible to describe. At the same time the findings indicate that other factors, such as training, affect the performance more. A comparison with the elite showed peak performance at the same age, but the rates of change in performance with age, improvement as well as degradation, was found to be higher among the elite.

Relation between dorsal and palmar hand skin temperatures during a cold stress test

Hand skin temperature measurements have previously been performed on either dorsal or palmar sides and it is possible to find arguments for the advantage of both locations. Therefore, the aim of this study was to use dynamic infrared (IR) imaging to examine the relationship between dorsal and palmar hand skin temperature. The palmar and dorsal hand skin temperature before and after a cold stress test was measured with IR thermography in 112 healthy participants. Calculation of surface average temperature was made from nine regions of interest on each hands dorsal and palmar side. Temperature values were recorded at baseline, directly after immersion of hands in vinyl gloves for one minute in water at 20 ±0.5 °C (gloves removed), and after eight minutes rewarming. Results showed that: a) the skin temperatures on the dorsal and palmar sides of the hand are strongly correlated; b) the correlation is stronger on the fingers than on the carpometacarpal (CMC) area; c) the palmar side of the CMC area is warmer than the dorsal side, but this is reversed in the fingers so that the nail bed is warmer than the finger pad; and d) the temperature difference ∆T between the dorsal and palmar sides of the fingers is independent of the skin temperature, though ∆T on the CMC area of the hand is temperature dependent. Such differences can be important in detailed investigations of thermal phenomena in the hand. In conclusion, results showed a strong correlation between the dorsal and palmar temperatures. If both sides cannot be measured, the purpose of the investigation should determine which side of the hand should be measured.