Friday August 28 2009
CEA
Alcohol: episodic memory and grey matter microstructure alteration
CEA
Researchers from the CEA’s Neuroimaging and Psychiatry unit (I²BM/SHFJ/Neurospin) working in collaboration with the Inserm, Paris 11 University, Paris 5 University, Stanford University and the Paris hospitals group (AP-HP) have just demonstrated ties between episodic memory[1] deficits in alcohol-dependents and microstructure alterations in the brain. These results were recently published in the 26 August online issue of PLoS One.
It has long been well-established that memory functions are altered in alcohol-dependents. This new study, which is highly original as it was led on detoxified, well-socially-adjusted alcoholics presenting no neurological or somatic complications, investigated the relationship between episodic memory performance, in-brain microstructure, and brain volumes. Three different testing programmes were conducted in 24 men who had quit drinking following alcohol withdrawal and in 24 healthy male volunteers. Episodic memory performance was assessed via neuropsychological tests. Detailed, in-depth brain structure was assessed using diffusion MRI to visually track in-brain water diffusion and thus picture the microstructure of the brain. This technique makes it possible to obtain a diffusion coefficient giving the distance travelled by a water molecule in a specified timeframe. Finally, overall brain volume was determined by anatomical MRI to get localized measurements of grey matter volume.
The results show that the diffusion coefficient is higher in abstinent alcoholics during withdrawal than in non-alcoholics. This suggests that there has been a structural alteration in the brain cells, i.e. neurones, axons, synapses, or glial cells, mainly in the frontal, temporal and parahippocampal regions along with the cerebellum. These brain regions also showed decreased grey matter volume. Statistical analysis revealed a correlation between the change in diffusion coefficient and the drop in episodic memory performance. However, there were no correlations between regional brain volumes and performances on episodic memory tests. Therefore, these diffusion MRI-based findings unambiguously show that memory deficit assessed in alcohol-dependents is related to changes in the brain’s microstructure rather than a decrease in brain volume. Diffusion MRI has the capacity to detect early-onset alcohol dependence-related alterations in brain structure. Looking at future perspectives, the prognostic value of these measurements warrants extensive and useful research.
[1] Episodic memory, also known as autobiographical memory, is the process that enables us to remember events in context, as we experienced them.
[1] Episodic memory, also known as autobiographical memory, is the process that enables us to remember events in context, as we experienced them.