Circulating Ghrelin as a Biomarker for Dementia

Inclusion criteria

• Age > 60 years
• Subject or carer / legal representative is willing to sign consent document

Specific criteria for each group;

Parkinson's Disease

• PD diagnosed by a movement disorder specialist and meets the diagnosis of PD
• MoCA > 26/30
• No evidence of cognitive symptoms causing functional impairment

Parkinson's Disease Dementia

• PD diagnosed by a movement disorder specialist
• Duration of motor symptoms > 1 year
• Meets MDS task force criteria for PDD
• MoCA < 21/30

Dementia with Lewy Bodies

• Meets criteria for probable DLB as defined by the 4th report of the DLB consortium

Alzheimer's Disease

• Meets criteria for probable AD dementia (consistent with NIA/AA core clinical criteria for probable AD dementia)

Exclusion criteria

• Age < 60 years
• Current major depression
• Use of anti-psychotic medication
• Type I or Type II diabetes mellitus (DM) (excluding diet-controlled DM)
• Tobacco use
• BMI <15.0 kg/m2
• BMI > 30 kg/m2
• Comorbid gastrointestinal disease i.e. includes Coeliac, active Inflammatory Bowel Disease (Colitis), evidence for active gastric ulcers within the last 12 months, but excludes gastroesophageal reflux and hiatus hernia.
• >5 kg weight change over the preceding 3 months (determined by researcher from previous clinic visit and discussion with partner/carer)
• Significant active comorbidity
• Difficult venous access
• Vagotomy

Additional disease specific exclusions;

• Parkinson's Disease exclusion criteria
• Evidence of dementia or mild cognitive impairment
• Deep brain stimulation (DBS)
• Use of Duodopa

Parkinson's Disease Dementia exclusion criteria

• Dementia within 12 months of diagnosis of PD
• DBS

Dementia with Lewy bodies exclusion criteria

• Onset of motor Parkinsonism symptoms greater than 12 months prior to dementia diagnosis

Alzheimer's dementia exclusion criteria

• Presence of PD, PDD, DLB, or Frontotemporal Dementia (FTD)

Controls exclusion criteria

• Evidence of parkinsonism
• Evidence of dementia or mild cognitive impairment
• MoCA <26/30