Cerebellar vermis size and cognitive ability in community-dwelling elderly men.

The cerebellum participates in multiple cognitive functions, including those that are sensitive to decline with aging, and is also vulnerable to atrophy with aging. However, few studies have examined structure-function relationships in older adults. We measured the cross-sectional area of four areas of the cerebellar vermis in 45 community-dwelling men aged 71-76, and correlated this with individual cognitive test scores and two cognitive factors derived from principal components analysis. Two out of the four areas showed positive correlations; vermis area 4 (lobules VIII-X) correlated at r = 0.47 (p = 0.001) with a general cognitive factor accounting for almost half of the cognitive test variance. These findings support the hypothesis that variations in cerebellar structure are associated with cognitive ability in older adults.

11ß-hydroxysteroid dehydrogenase type 1, brain atrophy and cognitive decline.

Excess cortisol levels are linked with brain atrophy and cognitive decline in older people. 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) potently amplifies intracellular glucocorticoid action by converting inert cortisone to active cortisol, but any causal importance in brain aging is unexplored. We tested the hypotheses that higher systemic 11ß-HSD1 activity predicts brain atrophy and cognitive decline in older men. In a longitudinal study of 41 men (65-70 years old at baseline) we measured baseline systemic 11ß-HSD1 activity, the urinary 5alpha- and 5beta-tetrahydrocortisol to tetrahydrocortisone ratio (ratio of tetrahydrometabolites of cortisol (THFs)/ratio of tetrahydrometabolites of cortisol (THE)), and assessed change in brain atrophy, white matter lesions and cognitive function over 6 years. Baseline THFs/THE correlated negatively with baseline hippocampal volumes (left: r = -0.37; right: r = -0.34; p < 0.05) and positively with ventricular volumes (r = 0.43, p = 0.006) and periventricular white matter lesions (rho = 0.31, p = 0.047). Importantly, baseline THFs/THE but not cortisol predicted increase in ventricular volumes (r = 0.33, p = 0.037) and decline in processing speed (r = -0.55, p = 0.0002) over 6 years. The predictive link between systemic 11ß-HSD1 activity and progressive brain atrophy and cognitive decline suggests 11ß-HSD1 inhibition as a plausible therapy for brain aging.

PTSD, attention bias, and heart rate after severe brain injury.

Does "partial" posttraumatic stress disorder (PTSD) occur after head injury? The authors found that attention bias to trauma-related threat stimuli and higher heart rate during trauma interview were not associated with PTSD symptom severity in 42 participants with severe head injury. They found no evidence for "partial" PTSD.

Higher systolic blood pressure is associated with increased water diffusivity in normal-appearing white matter.

BACKGROUND AND PURPOSE: Hypertension is associated with the development of white matter lesions in older people. Diffusion tensor MRI can detect subtle, previsible white matter damage, but relationships between diffusion tensor MRI parameters and blood pressure (BP) remain unclear. We examined correlations among mean diffusivity (MD), fractional anisotropy and BP in 45 men aged 71 to 76 years. METHODS: MD and fractional anisotropy were measured in 6 regions of interest in normal-appearing white matter. Visible white matter lesions were quantified using the Fazekas scale. Both were correlated with systolic and diastolic BP. RESULTS: Systolic BP was positively and significantly correlated with MD in all 6 regions (r=0.31 to 0.45; P=0.037 to 0.002). MD was also correlated with diastolic BP in the genu of the corpus callosum (r=0.34, P=0.018). A summary factor derived from principal component analysis of the MD measurements accounted for 53.8% of the variance and correlated at r=0.51 (P<0.001) with systolic BP and r=0.33 (P=0.028) with diastolic BP. Fractional anisotropy did not correlate significantly with BP. Deep white matter Fazekas scores correlated with diastolic BP (rho=0.35, P=0.019). CONCLUSIONS: The increase in MD without change in fractional anisotropy indicates that, in normal-appearing white matter, higher BP may be associated with increased extracellular fluid before any cytoarchitectural damage occurs.

Subjective memory complaints and cognitive impairment in older people.

Subjective memory complaints (SMCs) are common in older people and are often thought to indicate cognitive impairment. We reviewed research on the relationship between SMCs and (a) current cognitive function, (b) risk of future cognitive decline, and (c) depression and personality. SMCs were found to be inconsistently related to current cognitive impairment but were more strongly related to risk of future cognitive decline. However, SMCs were consistently related to depression and some personality traits, e.g. neuroticism. In conclusion, the determinants of SMCs are complex. The utility of SMCs in the diagnosis of pre-dementia states (e.g. mild cognitive impairment) is uncertain and requires further evaluation.