Table 7 Summary of findings of the effect of different levels of alcohol consumption compared to no or very low level (zero to <10 g/week) consumption on cognition
Certainty assessment | Impact | Certainty | Importance (of outcome) | ||||||
|---|---|---|---|---|---|---|---|---|---|
№ of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
Cognition (women only) (follow up: range 3 years to 13 years; assessed with: various scales and tests (standardised mean difference)) | |||||||||
5 | observational studies | very serious a | serious b | not serious | not serious c | none | There was no important difference in cognitive function between women who consumed one to two standard drinks (<20 grams of alcohol) per day and non-drinkers but the evidence is very uncertain. For alcohol consumption less than 25.9 grams alcohol/day (the point at which the predicted lower bound of the confidence interval crosses zero; ~2.5 standard drinks), cognition was slightly better in those consuming alcohol than current non-drinkers. However, the SMDs were small, with a maximum SMD of 0.18 (95%CI 0.02, 0.34), occurring at an intake of 14.4 grams alcohol/day. The effects are particularly uncertain at higher levels of alcohol consumption (>30 grams per day), since only one study (Kesse-Guyot 2012) contributes data for these levels of intake. | ⨁◯◯◯ VERY LOW | CRITICAL |
Cognition (men only) (follow up: range 1 years to 13 years; assessed with: various scales and tests (standardised mean difference)) | |||||||||
6 | observational studies | very serious a | serious d | not serious | not serious c | none | There was no important difference in cognitive function between men who consumed one to two standard drinks (<20 grams of alcohol) per day and non-drinkers but the evidence is very uncertain. The maximum SMD of 0.05 (95%CI 0.00, 0.10), occurring at an intake of 19.4 grams alcohol/day, was very small. For all levels of alcohol consumption, the predicted lower bound of the confidence interval of the SMD indicated that cognition was similar or poorer as compared to current non-drinkers, but the SMDs were small for alcohol intakes less than 55 grams/day. The effects are particularly uncertain at higher levels of alcohol consumption (>30 grams per day), since only one study (Kesse-Guyot 2012) contributes data for these levels of intake. | ⨁◯◯◯ VERY LOW | CRITICAL |
Cognition (women and men) (follow up: range 3 years to 34 years; assessed with: various scales and tests (standardised mean difference)) | |||||||||
4 | observational studies | very serious a | serious e | not serious | not serious c | none | There was no important difference in cognitive function between adults who consumed one to two standard drinks (<20 grams of alcohol) per day and non-drinkers but the evidence is very uncertain. The maximum SMD of 0.24 (95%CI -0.03, 0.51) occurred at an intake of 25 grams alcohol/day. For higher levels of alcohol consumption (e.g. >55 grams alcohol/day) there may be detrimental effects on cognition, however, this is where there is most uncertainty in the predictions, since only one study (Kitamura 2017) contributes data for these levels of intake. | ⨁◯◯◯ VERY LOW | CRITICAL |
Cognition (young people up to age 25) (follow up: range 12 months to years; assessed by: any scale or test or diagnostic criteria) | |||||||||
0 | None of the included studies examined the effects of different levels of alcohol consumption on cognition among young people, or the effects of different levels of alcohol consumption up to age 25 on cognition over the life-course (any age). Note, studies examining only acute effects (intoxication or withdrawal) were ineligible for the review. | - | CRITICAL | ||||||