Age and Sex Related Changes in Weight of the Whole brain : A Postmortem Study

Introduction: The brain, the part of central nervous system is regarded as the organ solely concerned with thought, memory, and consciousness, but these are only a few of its complex and varied functions. All information we have concerning the world about us is conveyed centrally to the brain by an elaborate nervous system. The brain is also concerned with all kinds of motor activity, with the regulation of visceral, endocrine and somatic functions, and with the receptive and expressive use of symbols and signs that underlie communication. While the gross features of the human brain are not especially impressive, its versatility, potential capabilities, efficiency, and self programming nature render it unique among all organs of the human body. The brain consists of the cerebral hemispheres, the brain stem, the diencephalon and the cerebellum1. It lies within the cranium2.Weight of the human brain is about 1400 gm1. Brain weight varies with age and gender. It decreases with age and also in many diseases. Lower brain weight was reported in schizophrenia3, Parkinson’s disease4, alcohol dependent person5 and brain weight of victim of fatal self-harm was significantly higher than those who died of natural causes6. Male brains are about 10% larger than female brains and weigh 11-12% more than that of a woman. This is due to the larger physical stature of

men.Male's larger muscle mass and larger body size requires more neurons to control them 7 .It is observed by reviewing existing literature that many studies have been done on human brain in foreign countries and showed significant variations were present among different age and sex groups.But there is no existing study on gross anatomy of human brain in our country.In order to find out any changes in weight of whole brain in relation to age and sex in Bangladeshi people we carried out this research.The findings of the present study are expected to help neurologists, radiologists and psychiatrists to adopt appropriate plans for diagnosis and management of diseases of human brain.

Materials and Methods:
The present study was performed on 70 brains of Bangladeshi cadavers of different age groups.The lowest age was 22 years in male and also in female and highest age was 58 years in male and 48 years in female.After completion of all legal formalities and requisite permission from the department of Forensic Medicine, the whole brains were collected from the unclaimed dead bodies during postmortem at the autopsy laboratory in the Department of Forensic Medicine, Dhaka Medical College, Dhaka, from February to December 2010.The whole brains were collected within 24 hours of death.During collection of the samples, appropriate age, sex and the cause of death were noted from the morgue's record book.The samples were brought to the Department of Anatomy, Dhaka Medical College, Dhaka.Soon after collection, each sample was gently washed with tap water and its surface was dried with blotting paper.Then weight of the whole brain was measured with the help of a weighing machine (Camry Weighing Scale, Camry Electronic Limited, China) in gm (Figure 1).Decomposed brains, injured brains were excluded.The study was approved by the Ethical Review Committee of Dhaka Medical College, Dhaka.For convenience of description, in relation to age, the collected samples were divided into four groups (according to Magnotta et al. 8 ).The samples were divided into four different age groups i.e.Group A (20-29 years), Group B (30-39 years), Group C (40-49 years) and Group D (50-59 years).The data collected from this study were processed to get mean values, standard deviations etc. as applicable.Statistical analyses were done by unpaired student's t test and one-way ANOVA.All the statistical analyses were done by using SPSS 15.0 version.

Results:
In the present study, the mean±SD weight of the whole brain was 1326.67±41.53 2).Significant differences were found in mean weight of the whole brain in male and female in group A (p=0.001), B (p=0.001) and C (p=0.001) (Table I).
The mean±SD weight of the whole brain was 1281.11±64.16gm, 1284.29±82.17gm, 1261.67±63.36gm and 1281.67±40.21gm in group A, B, C and D respectively.The highest value was found in group A and the lowest one was found in group C (Table II, Figure 3).The difference of mean weight in different age groups was not statistically significant (Table II).

Discussion:
In the present study the mean±SD weight of the whole brain was 1326.67±41.53

Conclusion:
It was revealed in the present study that weight of the brain was found to be declined with advancing age and male brain was heavier than female.During the due course time of one year only 70 samples could be collected and female samples were only 26.
Because there was no study about brain among Bangladeshi population, comparison could not be done here.Further studies with larger sample size with equal female samples are recommended.

Figure 1 :Figure 2 :Figure 3 :
Figure 1: Measurement of weight of the whole human brain.
gm, 1323.33±74.75gm, 1302.73±34.09gm and 1281.6±40.21gm in group A,B,C and D respectively in male and 1235.56±48.51gm, 1214.00±34.06gm and 1197.14±38.61gm in group A, B and C respectively in female (Table I, Figure

Table I : Weight of the whole brain in male and female in different age groups
Lowest value of weight in gm of the present study were similar to the findings of Nolte (2002), Ribero et al. (2002) but the highest value of their studies was much higher than values of any age group of the present study 10,11 .The weight of the brain of the present study was also lower than the findings of Witelson, Beresh and Kigar (2006) study and this dissimilarity may be due to racial variation.Findings of Pal, Chowdhury and Ghosh (2003) and Salib and Tadros (2000) were lower than the findings of the present study.Pal, Chowdhury and Ghosh (2003) did not mention age and sex of the study pop-Beresh and Kigar (2006) and also that of Riberio et al. (2002) 10,6,13,11 .The findings of the present study showed that the weight of the brain gradually decreased with advancing age and this finding agreed with the findings of Witelson, Beresh and Kigar (2006) 13 .