Brain Size May Predict Alzheimer’s Risk

the Psychiatry Advisor take:

Larger brain size could be associated with a reduced risk of cognitive impairment, dementia, and Alzheimer’s disease, according to research published in Alzheimer’s Research and Therapy.

The researchers, led by Aaron Bonner-Jackson of the Center for Brain Health at the Cleveland Clinic in Ohio, focused their study on the hippocampi, two “seahorse-shaped” structures in the left and right brain that help form memories. When they become impaired due to a condition such as Alzheimer’s disease, forming memories can become difficult. The left hippocampus is connected to verbal memory, and the right is connected with spatial memory.

The researchers analyzed 34 patients with Alzheimer’s and 82 with mild cognitive impairment, an Alzheimer’s precursor. They tested their verbal memories by asking them to remember lists of words read out loud, and tested their spatial memory by seeing how well they could remember shapes and patterns. They then examined brain scans recorded with magnetic resonance imaging.

The results show that patients with “normal” memory had larger hippocampi and performed better in the memory tasks compared with those who had cognitive impairment.

In addition, although previous studies have focused exclusively on verbal memory, results from this study show that spatial memory is important in assessing those at risk for Alzheimer’s.

Although this is one of the largest studies examining the relationship between the hippocampi and dementia, it was observational, so a causal relationship between brain size and cognitive function cannot be confirmed. The researchers state that more research is needed with larger sample sizes and examining more parts of the brain, including the thalamus and amygdala.