Geriatric Psychology on Brain Development - Dictionary of Arguments
Upton I 141
Brain Development/Geriatric psychology/Upton: Between the ages of 20 and 90, the brain shrinks, losing 5—10 per cent of its weight (Enzinger et al., 2005)(1).
A decrease in volume has also been observed; in one study the volume of the brains of older adults was around 15 per cent less than that of younger adults (Shan et al., 2005)(2).
Upton I 142
In one study it was found that brain volume reduces by 0.22 per cent every year between the ages of 20 and 65, then by 0.40 per cent per year from 65 to 80 years of age (Fotenos et aL, 2008)(3).
This is thought to be because of a combination of loss of dendrites, damage to myelin and the death of brain cells. Some areas of the brain shrink more than others as we age: the prefrontal cortex is one area that reduces in size and this has been linked to a decrease in cognitive function such as working memory (Grady et al.. 2006)(4).
Recent evidence has supported the idea that it is the structural changes in the brain that cause the loss of functioning (Fan et al.. 2008)(5).
However, we do not really know whether brain shrinkage leads to cognitive decline or vice versa. It is possible that this cause and effect model is too simplistic, as it fails to consider a number of environmental factors that may influence the impact of any biologically based changes in brain structure.
Fotenos et al. (2008)(3) have found, for example, that there is a complex relationship between socio-economic status, structural changes in the brain and cognitive decline.
The study found that, in older adults with no cognitive decline, those of higher socio-economic status showed more loss of brain volume when compared to individuals of lower socio-economic status. This does not mean that high socio-economic status is related to greater loss of brain volume, but rather that older adults from higher socio-economic groups respond differently to the same loss of brain volume than individuals from lower socio-economic backgrounds. >Social Status, >Dementia.
1. Enzinger, C, Fazekas F, Matthews, PM and Ropele S et al. (2005) Risk factors for progression of brain atrophy in aging: six-year follow-up of normal subjects. Neurology, 64(10): 1704-11.
2. Shan, Z, Liu, ¡Z, Sahgal, V, Wang, B, and Yue, GH (2005) Selective atrophy of left hemisphere and frontal lobe of the brain in old men.Journal of Gerontology: Series A, biological sciences and methcal sciences, 60(2): 165-74.
3. Fotenos, AF, Mintun, MA, Synder, AZ, Morris, JC and Buckner, RL (2008) Brain volume decline in aging: evidence for a relation between socioeconomic status, preclinical Alzheimer disease, and reserve. Neurology, 6 5(1): 113-20.
4. Grady, CL, Springer, MV, Hongwanishkul, D, McIntosh, AR and Winocur, G (2006) Age-related changes in brain activity across the adult lifespan.Journal of Cognitive Neuroscience, 18:227-41.
5. Fan, Y, Batmanghelich, N, Clark, CM, Davatzikos, C and Alzheimer’s Disease Neuroimaging Initiative (2008) Spatial patterns of brain atrophy in MCI patients, identified via high-dimensional pattern classification, predict sub sequent cognitive decline. Neuro image, 39: 1731-43._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
Developmental Psychology 2011