Mild cognitive impairment (MCI) is a common condition wherein cognitive problems are more severe than expected given a person’s age.¹ Memory becomes less efficient with age but such age-appropriate memory decline does not interfere significantly with function and activities of daily living (ADLs) are carried out about as well as before, all else being equal. If instrumental ADLs (eg. unable to handle medication) are impaired in cases of MCI there appears to an elevated risk for dementia.²

Prevalence of MCI depends on the diagnostic criteria used. There is a variable recall ability that causes subjective embarrassment: forgotten names, problems finding correct words, lost items, poor concentration, and problems present unusual challenges. There are no other cognitive deficiencies. Although the risk is increased³ close follow up is required to detect transition to dementia. Routine tests should be carried, eg. TFTs or, in alcoholics, B12. 

Current cognitive screening instruments do not allow us to confidently foretell prognosis in individual cases.^4,5 Cases recruited through advertisements fare better than people who go to mental health professionals with cognitive complaints. A six-year community-based study of over-75s⁶ found that 60-65% of MCI cases developed clinical dementia during life, most often within the first 18 months. In a meta-analysis of 41 studies⁷, researchers found a progression rate of only 10% and 5% per year in high- and low-risk groups respectively, and only 20-40% developed dementia after extended follow-up. MCI is a diagnosis by exclusion (depression, dementia, high anticholinergic load) and follow up.

At least in older women, sleep apnea may be a risk factor for MCI and dementia.⁸ The finding in a questionnaire-based study that the non-demented who take moderate exercise in mid- and later-life have a reduced likelihood of MCI⁹ does not answer whether cognitively intact subjects exercise more because they are cognitively intact! Treating vascular risk factors might reduce the rate of transition from MCI to Alzheimer’s disease.¹⁰ Galantamine is contraindicated in MCI: it does not prevent conversion to dementia and, whilst there was a suggestion of increased mortality this was not borne out in a recent study.¹¹

References

1. O’Shea B, Stokes M. Ir Psychiatrist 2008; 9: 158
2. Luck T et al. Psychol Med 2011; 41: 1087-97
3. Jessen F et al. Arch Gen Psychiatry 2010; 67: 414-22
4. Lonie JA et al. Internat J Geriatr Psychiatry 2009; 24: 902-15
5. Lonie JA et al. Br J Psychiatry 2010; 197: 135-40
6. Busse A et al. Br J Psychiatry 2006; 189: 399-404
7. Mitchell AJ, Shiri-Feshki M. Acta Psychiatr Scand 2009; 119: 252-65
8. Yaffe K et al. JAMA 2011; 306: 613-19
9. Geda YE et al. Arch Neurol 2010; 67: 80-6
10. Li et al. Neurology 2011; 76: 1485-91
11. Winblad B et al. Neurology 2008; 70: 2020-1