An international collaboration has shed light on the basal forebrain region, where the degeneration of neural tissue caused by Alzheimer’s disease appears even before cognitive and behavioral symptoms of the disease emerge.

The research, published in Nature Communications, used data obtained from the Alzheimer’s Disease Neuroimaging Initiative database.

The basal forebrain contains very large and densely connected neurons that are particularly vulnerable to the disease. The researchers show that, as Alzheimer’s progresses, degeneration of the basal forebrain predicts subsequent degeneration in temporal lobe areas of the brain involved in memory. This pattern is consistent with other research showing that Alzheimer’s indeed spreads across brain regions over time, but the study challenges a widely held belief that the disease originates in the temporal lobe.

In the two-year study, the researchers were able to determine that individuals with MCI or Alzheimer’s disease showed greater losses in gray matter volume in both the basal forebrain and temporal lobe, compared with cognitively normal controls. Intriguingly, they showed that over the two-year period, degeneration of neural tissue in the basal forebrain predicted subsequent tissue degeneration in the temporal lobe, but not the other way around.

A sampling of spinal fluid from healthy adults can detect an abnormal level of beta amyloid, indicative of Alzheimer’s. Test results showed that temporal lobes looked the same regardless of amyloid level, but the basal forebrain showed notable degeneration among those seemingly healthy adults with abnormal amyloid levels.

Paper: “Basal forebrain degeneration precedes and predicts the cortical spread of Alzheimer’s pathology”
Reprinted from materials provided by Cornell University.