As there is no single symptom pattern that signals the start of dementia with Lewy bodies (DLB), getting a diagnosis is commonly delayed. Finding a definitive medical test that confirms the presence of Lewy bodies during life is still being hotly pursued by scientists. A new study out of the UK reveals one brain scan may be helpful in identifying DLB very early, during mild cognitive impairment (MCI).
The study recruited 75 people diagnosed with MCI and whose symptoms resembled either very early DLB or Alzheimer’s disease. The subjects were divided based on their symptoms into three groups. Those with 2 symptoms of DLB were considered probable MCI due to Lewy bodies (MCI-LB). Those with one DLB symptom fell into the possible MCI-LB category, and those with none were grouped as MCI likely due to Alzheimer’s disease (MCI-AD).
All participants also had FP-CIT imaging (DaTSCAN) performed, to determine if they had a loss of dopamine-producing brain cells. This abnormal result is a common finding in people with DLB, but not in Alzheimer’s disease. The results were then rated visually as normal or abnormal by ‘blinded’ reviewers, who did not know the subject’s diagnosis. Scan results were also analyzed by a specialized software called DaTQUANT.
Nearly 2/3rds (61%) of the probable MCI-LB cases had abnormal scan results, supporting the MCI-LB diagnosis. In those with possible MCI-LB, only 40% had abnormal results. Three people in the MCI-AD group also had abnormal scans. Of those with abnormal FP-CIT scan results, 89% supported the probable or possible MCI-LB diagnosis. Abnormal results increased the probability of having MCI-LB by about 30%. (It is important to note that approximately 30% of people with DLB have normal FP-CIT scans. This means a normal result does not rule out a diagnosis of DLB.)
Subjects were assessed annually for up to 3 years, with a mean follow-up of 1.5 years. Of those who died during follow-up, four individuals agreed to brain autopsies, allowing for final diagnosis. Twenty-one people went on to develop dementia during that time. All developed the same type of dementia they had originally been grouped in at the start of the study. The three subjects with MCI-AD and abnormal scans later developed either one symptom of DLB or also had an abnormal cardiac nerve scan, suggestive of DLB over AD.
While further research is needed to confirm these findings, this study suggests that FP-CIT imaging may be clinically useful in detecting DLB before the onset of dementia.
This study was supported by the National institute for Health Research (NIHR) Newcastle Biomedical Research Unit in Lewy Body Dementia, based at Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University.