1500 g. This was the weight of President Kennedy’s brain during the pathological examination made at the Bethesda Naval Hospital on December 6, 1963 . The brain weight figure allows to infer on the weight of President’s brain at the time of autopsy. Unfortunately, the Bethesda pathologists did not weigh President’s brain during the autopsy in spite of this procedure being a routine part of every autopsy .
A three week formalin fixation has been shown to increase the brain weight by 50 g on average . More recent data suggest a variable percent increases in brain weights due to the formalin fixation with an average weight increase of 8.8% over the period of few weeks . If we apply the swelling factor of 8.8%, the estimated weight of President Kennedy’s brain at the time of autopsy was 1373 g.
This figure appears to be too large relative to the amount of damage to the President Kennedy’s brain. The damage to the right hemisphere and the associated loss of brain tissue has been estimated by Mr. David Lifton to be as much as 70% in the right hemisphere . If a normal brain would suffer such loss of tissue, it could not weigh 1373 g. To provide some approximation of the weight of intact and injured Kennedy’s brain, normative data obtained in large cohorts of people can be used. The study by Debakan et al. (1978)  analysed the post-mortem brain weights in 2773 males and 1963 females in 23 age categories. The mean weight of a male brain in the age range of 40-50 years was 1430 g (standard deviation 20 g). As President Kennedy was tall (72.5 inches, 184 cm), and since brain weight correlates with body height and weight , it is reasonable to estimate that the weight of Kennedy’s brain would be in the upper range of the normal distribution of brain weights in his age category. The upper weight value corresponding to the top 5% brain weights for males aged 40-50 years, estimated using the Z-scores method, would be 1496.2 g (rounded to 1496 g). If Kennedy’s brain sustained a loss of 70% of brain tissue in one hemisphere , his brain at the time of autopsy weighed only 972 g. However, even if we accept a smaller than 70% loss of brain tissue of 50% in one hemisphere, the brain weight at the time of autopsy would be only 1122 g. After correcting these brain weight estimates for swelling due to immersing the brain into a formalin solution, Kennedy’s brain during the pathological examination on December 6 was expected to weigh 1058 g or 1221 g for a 70% and 50% loss of tissue in one hemisphere, respectively.
These calculations suggest that the brain examined on December 6, 1963 was different from the brain removed from President Kennedy’s skull during the autopsy on November 22, 1963. Further, this finding sheds a new light on the omission to weigh the brain during the autopsy . The following two explanations need to be considered:
- The pathologists were stressed out and confused during the autopsy itself and forgot to measure the brain weight. This would be an unlikely but honest error.
- The pathologists intentionally skipped weighing the brain during the autopsy either to conceal the real loss of brain tissue, and/or to be able to use a different brain in further examinations. The correct brain weight data at the time of autopsy might have prevented the use of a different brain as the other brain would have been weighed during the follow-up pathological examination of the fixated brain, and the discrepancy in the autopsy and post-autopsy weights would be evident. If this explanation is correct, it is also conceivable that the generals and some unknown civilians present in the autopsy room  couched or ordered Dr. Humes and Dr. Boswell not to weigh the brain.
As my calculations suggest that other than President Kennedy’s brain was examined on December 6, I am inclined to accept the latter explanation. The calculations and the conclusion accord a previous note by Mr. Doug Horne (2006) that the weight of 1500 g would be too large for the brain showing extensive tissue loss .
 Appendix IX. Commission Exhibit 391. Supplementary report of autopsy number A63-272. https://www.archives.gov/research/jfk/warren-commission-report/appendix-09.pdf
 During his deposition for the ARRB, the interviewers asked Dr. Humes about the lack of the weight figure in the autopsy form. Dr. Humes had a difficult time to explain (ARRB deposition 1996, pp. 74-75):
- I’d like to draw your attention to a few items on the first page of this document. Right next to the marking for brain, there’s no entry of a weight there. Do you see that on the document?
A. Yes, I see that it’s blank, yeah.
Q. Why is there no weight for the brain there?
A. I don’t know. I don’t really–can’t really recall why.
Q. Was the fresh brain weighed?
A. I don’t recall. I don’t recall. It’s as simple as that.
Q. Would it be standard practice for a gunshot wound in the head to have the brain weighed?
A. Yeah, we weigh it with gunshot wound or no. Normally we weigh the brain when we remove it. I can’t recall why–I don’t know, one, whether it was weighed or not, or, two, why it doesn’t show here. I have no explanation for that
 Frýdl V, Koch R, Závodská H. The effect of formalin fixation on several properties of the brain. Zentralbl. Allg. Pathol. 135:649-55 (1989)
 Itabashi, H.H., Andrews, J.M., Tomiyasu, U., Erlich, S.S., Sathyavagiswaran, L. Forensic Pathology: A Practical Review of the Fundamentals. Academic Press & Elsevier, 2007, p. 22.
 Lifton, D. Best Evidence. Disguise and Deception in the Assassination of John F. Kennedy. Carroll & Graf Publishers, Inc., New York, Fourth Edition, 1989, pp. 470-472.
 Debakan, A.S., Sadowsky, D. Changes of brain weights during the span of human life: relation of brain weights to body heights and body heights. Ann. Neurol., 4: 345-356, 1978.
 Spartacus Educational Forum, thread: Cover-up of medical evidence. Post by Doug Horne, dated May 16, 2006, No. 3. http://educationforum.ipbhost.com/index.php?showtopic=6849&hl=