REM Sleep Behavior Disorder (RBD) is sometimes called “Active Dreams” because people who have it physically act out their dreams in their sleep. There is a chemical switch in the brain that turns off mobility during dreams, allowing a more restful sleep. When the switch is damaged, a sleeping person may thrash their arms and legs around, talk out loud and become violent.
When the brains from people who had been diagnosed with RBD, or Active Dreams, were autopsied, researchers continually found Lewy bodies even when no other Lewy body disorder was present. Thus we consider the disorder a member of the Lewy body family, usually the first one to appear. Although RBD can occur alone, it can accompany Parkinson’s disease and both types of Lewy body dementia and may show up before any other Lewy body disorder. Active Dreams have long been considered a serious predictor of Dementia with Lewy Bodies (DLB). They are often the first precursor to appear, and can show up decades prior to dementia symptoms.
Recent studies have explored the relationships between RBD, PD and LBD further. They have found that there is at least a 65% chance that a person with Active Dreams will develop an alpha-synuclein-based disorder within an average of 11 years of an RBD diagnosis. Alpha-synuclein is the protein that when damaged, can become Lewy bodies, which causes both PD and DLB. The other member of this group is Multiple System Atrophy (MSA) which affects the Autonomic Nervous System similar to the way LBD does. MSA does not belong to the Lewy Body family, but it is a close cousin, with its cause being another type of damaged alpha-synuclein protein.
One of those studies found that Active Dreams developed prior to PD over half the time. Of this RBD first, then PD group, half also showed signs of Mild Cognitive Impairment (MCI) prior to their PD diagnosis. All of this RBD/MCI first, then PD group, all went on to develop dementia before the four year study ended. None of those with Active Dreams but no MCI at Parkinson’s diagnosis developed dementia before the end of the four years.
Thus, anyone who experienced Active Dreams prior to their PD diagnosis should be examined for MCI. If this is present, it is imperative for you to make plans for the future—while you still can. Dementia will likely follow soon. If MCI is not present, then dementia may wait many years to appear—if it ever does. However, be forewarned: you still need to plan ahead. People have been known to develop dementia 50 years after the onset of RBD. Therefore, this does not give you an “all clear.” It simply gives you hope of more years of dementia free living.