Mild cognitive symtoms

Enrollment

Within the Swedish BioFINDER study, 500 patients with mild cognitive symptoms (MCS)  have been consecutively included between 2010 and 2015 from the Memory clinic at Skåne University Hospital and Ängelholm’s Hospital in Sweden for this prospective, longitudinal cohort study. All patients have been referred to the memory clinics due to subjective or objective cognitive impairment as part of routine clinical practice. Approximately 40-60% of the patients are expected to develop a dementia disorder such as Alzheimer’s disease, vascular dementia, dementia with Lewy bodies or Parkinson’s disease dementia.

Inclusion criteria

  • Referred to the memory clinics due to cognitive symtoms experienced by the patient and/or informant. These symptoms do not have to be memory complaints, but could also be executive, visuo-spatial, language, praxis or psychomotor complaints.
  • Age between 60 and 80 years.
  • MMSE score of 24 – 30 points at baseline visit.
  • Do not fulfill the criteria for any dementia.
  • Speaks and understands Swedish to the extent that an interpreter not was necessary for the patient to fully understand the study information and neuropsychological tests.

Exclusion criteria

  • Significant unstable systemic illness or organ failure, such as terminal cancer, that makes it difficult to participate in the study.
  • Current significant alcohol or substance misuse.
  • Refusing lumbar puncture or neuropsychological assessment.
  • The cognitive impairment at baseline visit can with certainty be explained by another condition or disease such as normal pressure hydrocephalus, major cerebral hemorrhage, brain infection, brain tumor, multiple sclerosis, epilepsy, psychotic disorders, severe depression, alcohol abuse the last five years, on-going medication with drugs that invariably cause cognitive impairment (such as high-dose benzodiazepines).

Examinations

Follow-up

The participants will be followed for at least 6 years. The baseline investigations above are repeated every 24 months, and cognitive tests and scales every 12 months.

Classification of mild cognitive impairment (MCI)

The patients are classified into MCI subtypes on the basis of the neuropsychological test results. The normative standard scores are all transformed into z-scores and a mean z-score for each cognitive domain score is calculated. The main principle is that an impaired function is defined as a mean score ≤ -1.5 z-score. However, a higher performance can also be classified as MCI if this is considered to be significantly below estimated premorbid level of intellectual function (as determined by a neuropsychologist’s judgment based on the patients’ education and the results of the other tests).

Criteria for the different subtypes

  • Amnestic single domain MCI
    Impaired performance on tests of episodic memory.
  • Amnestic multi-domain MCI: Impaired performance on test of at least one cognitive domain in addition to episodic memory.
  • Non-amnestic single-domain MCI: Impaired performance in only one cognitive domain except episodic memory.
  • Non-amnestic multi-domain MCI: Impaired performances in at least two non-memory       cognitive domains.
  • Subjective cognitive decline (SCD): No significant impairment in any test.