Issue 11, Pages 823-829 1 December 2004  |
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Study title and authors:
Randomized trial of the effects of simvastatin on cognitive functioning in hypercholesterolemic adults
Matthew F. Muldoon, MD, MPHa, Christopher M. Ryan, PhDb, Susan M. Sereika, PhDc, Janine D. Flory, PhDd, Stephen B. Manuck, PhDd
This study can be accessed at: http://www.amjmed.com/article/S0002-9343(04)00546-7/abstract
The study investigated the effects of statin therapy on cognitive functioning. The study, which employed a randomized double-blind design, comprised 308 adults between 35 and 70 years of age who had low density lipoprotein (LDL) cholesterol levels between 160 - 220 mg/dL (4.1 - 5.7 mmol/L). For six months the participants were assigned to daily treatment of either:
(i) Placebo.
(ii) 10 mg of simvastatin.
(iii) 40 mg of simvastatin.
Neuropsychological tests were administered to assess cognitive functioning at the start of the study and at the end of the treatment period.
Based on observations from a previous study, the tests were grouped into three categories:
(1) Statin sensitive tests:
The study investigated the effects of statin therapy on cognitive functioning. The study, which employed a randomized double-blind design, comprised 308 adults between 35 and 70 years of age who had low density lipoprotein (LDL) cholesterol levels between 160 - 220 mg/dL (4.1 - 5.7 mmol/L). For six months the participants were assigned to daily treatment of either:
(i) Placebo.
(ii) 10 mg of simvastatin.
(iii) 40 mg of simvastatin.
Neuropsychological tests were administered to assess cognitive functioning at the start of the study and at the end of the treatment period.
Based on observations from a previous study, the tests were grouped into three categories:
(1) Statin sensitive tests:
Elithorn Mazes: Planning and drawing time to complete complex lattice-type perceptual mazes.
Digit Vigilance: Number of target stimuli (the number “6”) missed when required to scan two pages
of numbers.
Recurring Words: Percentage of words identified correctly as either “new” or “repeated” when words are read using a continuous recognition test format.
Grooved Pegboard: Time required to insert 25 grooved pegs into slotted holes.
(2) Statin insensitive tests:
Digit Symbol: Time required to recode numbers into symbols using a key that pairs each of nine digits with a meaningless shape. Time converted to scaled, normalized score.
Stroop Interference: Viewing a list of color words printed in an incongruous ink color, participants say each ink color as quickly as possible (seeing “red” printed in blue ink, they respond “blue”). Number correct is converted to a scaled, normalized score.
Trail Making B: Time required to draw a line connecting alternating numbers and letters (e.g., 1-A-2-B) that are arrayed on a piece of paper.
Digit Span: Longest span of digits correctly recalled forwards and longest span recalled backwards. Sum of spans is converted into scaled, normalized score.
Complex Figure: Score on the reproduction of the Rey or Taylor figure, drawn from memory 30 minutes after having copied the figure.
Letter Rotation: Number of stimuli (the letters F, L, or R rotated 0°, 30°, 60°, 90°, 120°, 150°, or 180°) misidentified as being either oriented normally or reversed.
(3) New tests:
Mirror Tracing: Number of errors made when tracing over a star pattern that can be seen only in mirror-reversed view.
4-Word Short-Term Memory: Across several trials, the number of words correctly recalled after intervening distraction consisting of serial subtraction arithmetic for 15 or 30 seconds.
The study found:
(a) In the statin sensitive tests, patients on placebo improved their perfomance, whilst patients on statins did not.
(b) In the statin insensitive tests there was little difference between the placebo and statin groups, although the placebo group improved slightly more than the statin groups.
(c) In the new tests, cognition improved more in the placebo group compared to the statin groups.
The results of the study reveal that statins may be detrimental to cognitive functioning.
The study found:
(a) In the statin sensitive tests, patients on placebo improved their perfomance, whilst patients on statins did not.
(b) In the statin insensitive tests there was little difference between the placebo and statin groups, although the placebo group improved slightly more than the statin groups.
(c) In the new tests, cognition improved more in the placebo group compared to the statin groups.
The results of the study reveal that statins may be detrimental to cognitive functioning.
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