Premorbid Brain Volume and Dementia

Intracranial volume and dementia: Some evidence in support of the cerebral reserve hypothesis

“…However, it is noteworthy that HC is an indirect measure of cranial capacity correlating only moderately (r ~ 0.6, R 2 ~ 0.36) with actual brain size in typically developing adolescents and adults (Lainhart et al, 1997). In contrast, TICV among typically aging adults as measured by our lab is significantly associated with brain volume (r = 0.89) accounting for approximately 79% of the variability associated with total brain volume with the difference between TICV and brain volume being less than 191 ml 3 in healthy controls regardless of age (Bigler et al, 2001; Blatter et al, 1995). This represents a methodological improvement over external measures of HC that is sometimes complicated by variable amounts of fascia, skin, and bone captured in this measures (Tate et al, 2007).…”

“…The first limitation lies in the fact that TICV is only a proxy measure of premorbid brain volume or size. Though studies in the literature have consistently demonstrated significant relationships between TICV and brain volume in healthy typically developing adolescents and adults (Bigler & Tate, 2001; Courchesne, et al, 2000), it is not a perfect one-to-one relationship. Practically speaking, this means that TICV does not always capture possible demographic, nutritional, social, and educational factors that may also operate to impact premorbid brain volume and that this fact may actually make these results more difficult to interpret.…”

“…Consequently, for AD it appears (and potentially MA/MCI subjects at risk for AD) that the TICV effect may be nested within a larger group of demented subjects where premorbid size is a factor. In addition, the TICV effect may merely be an epiphenomenon where total brain size actually relates to component structures of the brain and it is the size of the component structure—i.e., mesial temporal cortex, hippocampus or some other target structure—where the true size effect occurs (Bigler, 2001). Thus, a reduction in the size of a given target structure (i.e., hippocampus), not necessarily the whole brain, may be critical in who develops dementia.…”

Intracranial volume and dementia: Some evidence in support of the cerebral reserve hypothesis

“…However, it is noteworthy that HC is an indirect measure of cranial capacity correlating only moderately (r ~ 0.6, R 2 ~ 0.36) with actual brain size in typically developing adolescents and adults (Lainhart et al, 1997). In contrast, TICV among typically aging adults as measured by our lab is significantly associated with brain volume (r = 0.89) accounting for approximately 79% of the variability associated with total brain volume with the difference between TICV and brain volume being less than 191 ml 3 in healthy controls regardless of age (Bigler et al, 2001; Blatter et al, 1995). This represents a methodological improvement over external measures of HC that is sometimes complicated by variable amounts of fascia, skin, and bone captured in this measures (Tate et al, 2007).…”

“…The first limitation lies in the fact that TICV is only a proxy measure of premorbid brain volume or size. Though studies in the literature have consistently demonstrated significant relationships between TICV and brain volume in healthy typically developing adolescents and adults (Bigler & Tate, 2001; Courchesne, et al, 2000), it is not a perfect one-to-one relationship. Practically speaking, this means that TICV does not always capture possible demographic, nutritional, social, and educational factors that may also operate to impact premorbid brain volume and that this fact may actually make these results more difficult to interpret.…”

“…Consequently, for AD it appears (and potentially MA/MCI subjects at risk for AD) that the TICV effect may be nested within a larger group of demented subjects where premorbid size is a factor. In addition, the TICV effect may merely be an epiphenomenon where total brain size actually relates to component structures of the brain and it is the size of the component structure—i.e., mesial temporal cortex, hippocampus or some other target structure—where the true size effect occurs (Bigler, 2001). Thus, a reduction in the size of a given target structure (i.e., hippocampus), not necessarily the whole brain, may be critical in who develops dementia.…”

Premorbid Brain Volume Estimates and Reduced Total Brain Volume in Adults Exposed to Trauma With or Without Posttraumatic Stress Disorder: A Meta-analysis

“…Fourth, TICV is at best only an estimate of premorbid brain volume and includes nonbrain components of the intracranial vault, such as cerebral spinal fluid and vasculature. To what extent these nonbrain tissues may affect TICV is unknown, 29 making prospective longitudinal brain volume studies initiated before trauma exposure a more effective way to investigate the possibility of brain atrophy in PTSD. However, such research is expensive and difficult, leaving estimates of premorbid brain volume a reasonable method to study the potential for brain atrophy in PTSD.…”

Cerebral volume loss, cognitive deficit and neuropsychological performance: Comparative measures of brain atrophy: I. Dementia

“…In degenerative disease the typical measure of brain volume is usually represented as total parenchymal brain volume adjusted in some fashion for head size by total intracranial volume (TICV; Cahn et al, 1998;Fama et al, 2000;Forstl et al, 1996;Jack et al, 1998;Killiany et al, 2000;Shear et al, 1995;Tanabe et al, 1997;Wilson et al, 1996), which can also serve as the basis for an estimate of premorbid brain volume (Bigler, 2001;Jenkins et al, 2000). Total brain volume (TBV) corrected in this manner has been shown to reliably relate to cognitive performance in a number of domains, particularly memory and executive function (Cahn et al, 1998;Wilson et al, 1996).…”

Intracranial volume and dementia: Some evidence in support of the cerebral reserve hypothesis

“…However, it is noteworthy that HC is an indirect measure of cranial capacity correlating only moderately (r ~ 0.6, R 2 ~ 0.36) with actual brain size in typically developing adolescents and adults (Lainhart et al, 1997). In contrast, TICV among typically aging adults as measured by our lab is significantly associated with brain volume (r = 0.89) accounting for approximately 79% of the variability associated with total brain volume with the difference between TICV and brain volume being less than 191 ml 3 in healthy controls regardless of age (Bigler et al, 2001; Blatter et al, 1995). This represents a methodological improvement over external measures of HC that is sometimes complicated by variable amounts of fascia, skin, and bone captured in this measures (Tate et al, 2007).…”

“…The first limitation lies in the fact that TICV is only a proxy measure of premorbid brain volume or size. Though studies in the literature have consistently demonstrated significant relationships between TICV and brain volume in healthy typically developing adolescents and adults (Bigler & Tate, 2001; Courchesne, et al, 2000), it is not a perfect one-to-one relationship. Practically speaking, this means that TICV does not always capture possible demographic, nutritional, social, and educational factors that may also operate to impact premorbid brain volume and that this fact may actually make these results more difficult to interpret.…”

“…Consequently, for AD it appears (and potentially MA/MCI subjects at risk for AD) that the TICV effect may be nested within a larger group of demented subjects where premorbid size is a factor. In addition, the TICV effect may merely be an epiphenomenon where total brain size actually relates to component structures of the brain and it is the size of the component structure—i.e., mesial temporal cortex, hippocampus or some other target structure—where the true size effect occurs (Bigler, 2001). Thus, a reduction in the size of a given target structure (i.e., hippocampus), not necessarily the whole brain, may be critical in who develops dementia.…”

Premorbid Brain Volume Estimates and Reduced Total Brain Volume in Adults Exposed to Trauma With or Without Posttraumatic Stress Disorder: A Meta-analysis

“…Fourth, TICV is at best only an estimate of premorbid brain volume and includes nonbrain components of the intracranial vault, such as cerebral spinal fluid and vasculature. To what extent these nonbrain tissues may affect TICV is unknown, 29 making prospective longitudinal brain volume studies initiated before trauma exposure a more effective way to investigate the possibility of brain atrophy in PTSD. However, such research is expensive and difficult, leaving estimates of premorbid brain volume a reasonable method to study the potential for brain atrophy in PTSD.…”

Cerebral volume loss, cognitive deficit and neuropsychological performance: Comparative measures of brain atrophy: I. Dementia

“…In degenerative disease the typical measure of brain volume is usually represented as total parenchymal brain volume adjusted in some fashion for head size by total intracranial volume (TICV; Cahn et al, 1998;Fama et al, 2000;Forstl et al, 1996;Jack et al, 1998;Killiany et al, 2000;Shear et al, 1995;Tanabe et al, 1997;Wilson et al, 1996), which can also serve as the basis for an estimate of premorbid brain volume (Bigler, 2001;Jenkins et al, 2000). Total brain volume (TBV) corrected in this manner has been shown to reliably relate to cognitive performance in a number of domains, particularly memory and executive function (Cahn et al, 1998;Wilson et al, 1996).…”

Intracranial volume and dementia: Some evidence in support of the cerebral reserve hypothesis

“…However, it is noteworthy that HC is an indirect measure of cranial capacity correlating only moderately (r ~ 0.6, R 2 ~ 0.36) with actual brain size in typically developing adolescents and adults (Lainhart et al, 1997). In contrast, TICV among typically aging adults as measured by our lab is significantly associated with brain volume (r = 0.89) accounting for approximately 79% of the variability associated with total brain volume with the difference between TICV and brain volume being less than 191 ml 3 in healthy controls regardless of age (Bigler et al, 2001; Blatter et al, 1995). This represents a methodological improvement over external measures of HC that is sometimes complicated by variable amounts of fascia, skin, and bone captured in this measures (Tate et al, 2007).…”

“…The first limitation lies in the fact that TICV is only a proxy measure of premorbid brain volume or size. Though studies in the literature have consistently demonstrated significant relationships between TICV and brain volume in healthy typically developing adolescents and adults (Bigler & Tate, 2001; Courchesne, et al, 2000), it is not a perfect one-to-one relationship. Practically speaking, this means that TICV does not always capture possible demographic, nutritional, social, and educational factors that may also operate to impact premorbid brain volume and that this fact may actually make these results more difficult to interpret.…”

“…Consequently, for AD it appears (and potentially MA/MCI subjects at risk for AD) that the TICV effect may be nested within a larger group of demented subjects where premorbid size is a factor. In addition, the TICV effect may merely be an epiphenomenon where total brain size actually relates to component structures of the brain and it is the size of the component structure—i.e., mesial temporal cortex, hippocampus or some other target structure—where the true size effect occurs (Bigler, 2001). Thus, a reduction in the size of a given target structure (i.e., hippocampus), not necessarily the whole brain, may be critical in who develops dementia.…”

Premorbid Brain Volume Estimates and Reduced Total Brain Volume in Adults Exposed to Trauma With or Without Posttraumatic Stress Disorder: A Meta-analysis

“…Fourth, TICV is at best only an estimate of premorbid brain volume and includes nonbrain components of the intracranial vault, such as cerebral spinal fluid and vasculature. To what extent these nonbrain tissues may affect TICV is unknown, 29 making prospective longitudinal brain volume studies initiated before trauma exposure a more effective way to investigate the possibility of brain atrophy in PTSD. However, such research is expensive and difficult, leaving estimates of premorbid brain volume a reasonable method to study the potential for brain atrophy in PTSD.…”

Cerebral volume loss, cognitive deficit and neuropsychological performance: Comparative measures of brain atrophy: I. Dementia

“…In degenerative disease the typical measure of brain volume is usually represented as total parenchymal brain volume adjusted in some fashion for head size by total intracranial volume (TICV; Cahn et al, 1998;Fama et al, 2000;Forstl et al, 1996;Jack et al, 1998;Killiany et al, 2000;Shear et al, 1995;Tanabe et al, 1997;Wilson et al, 1996), which can also serve as the basis for an estimate of premorbid brain volume (Bigler, 2001;Jenkins et al, 2000). Total brain volume (TBV) corrected in this manner has been shown to reliably relate to cognitive performance in a number of domains, particularly memory and executive function (Cahn et al, 1998;Wilson et al, 1996).…”