Search

The widespread use of antidepressants since the late 1950s and especially the ambulatory treatment of the majority of depressive patients raises the issue of the state of knowledge of the effects of these drugs on cognitive function. This review aims at synthesizing information about differential effects of antidepressants on cognitive function to facilitate good prescription. The first part of this review tries to summarize the main tasks used to explore global reactivity, attention, memory and psychomotor performances. The second part of this work presents the differential cognitive effects of antidepressants with a discrimination between substances which have a sedative impact, antidepressants with no cognitive effect, and drugs which seem to have a positive cognitive action. The differenciation is established for single and repeated administration, for healthy volunteers and depressed subjects. For each substance, the dose, the tasks selected and cognitive effect are discussed and the question of the real benefit of this cognitive impact is raised. The specificity of cognitive effects of antidepressants related to age and to the combination with alcohol are also tackled. Then the discussion raises the difficulty and the biases encountered to perform neuropsychological studies and particularly evaluation of cognitive effects of antidepressants. Finally the conclusion of this review gives some advice to select and prescribe antidepressants according to their cognitive effects.

SummaryA study was performed in young healthy volunteers in order to test the possible action of tianeptine, a new antidepressant drug, on cognitive performances. Attention tests, memory tests, a non-verbal inductive reasoning test and a sleep questionnaire were used in this double-blind placebo-controlled crossover study. The two one-week drug administration periods were separated by a one-week wash-out period. The methodology permitted us to evaluate the learning effect during the familiarization with the tests and to clear the results of the study from this parameter which could possibly distort analysis. For this large range of tests, the results showed that tianeptine did not affect the level of functioning of the volunteers after their familiarization with the tests. These results are in contrast with those obtained by different authors with classical tricyclic antidepressants.

In this review the authors propose to study the impact of antidepressants on attention, memory and motor functions in healthy volunteers and depressed patients on single and long-term administration. After reviewing the principal cognitive functions, we examine the actual investigation means to conclude that the Critical Flicker Fusion Test (CFFT) is one of the most drug-sensitive tests. It permits a categorization in: sedative antidepressants that in single administration lower CFFT; compounds with no effect on CFFT and no deleterious cognitive effect; and finally substances that raise CFFT and may have psychostimulating properties. On single administration amitriptyline is the most sedative antidepressant on attention or motor level. It seems to produce negative effects on memory level. However, experimental trials give contradictory results. Imipramine in single administration also has sedative effects on memory and car driving capacity. However divergent results of experimental trials do not allow any conclusions of a clearcut negative cognitive effect. Memory impairments with imipramine appear at administration levels of 150 mg. Mianserin has a sedative impact on attention and motor level at low doses (10 mg). Among the tricyclics, nortriptyline has a highly dose dependent sedative effect that has been shown on attention tests (Time Reaction:TR, Digit Symbol Substitution Test: DSST). Among non-tricyclic compounds, doxepine lowers attention and motor performances. Maprotiline (75 mg) lowers CFFT and has a dose dependent effect. Trazodone also has a negative impact on attention tests. Finally viloxazine lowers CFFT but does not impair other attention or motor tests on a 100 mg doses. Buspirone, lofepramine, midalcipran and zimelidine are antidepressants with no effect on CFFT and do not have any positive or negative cognitive effect. On the other hand nomifensine, paroxetine and fluoxetine raise CFFT in healthy volunteers on single administration. Improvement of CFFT performances was found in an isolated manner for nomifensine and paroxetine on 30 mg doses with no other memory or motor effects. MAO-Inhibitors do not impair attention or motor function; thus moclobemide has no negative impact on memory, attention or car driving tests. Cognitive impact of antidepressants in depressive patients seems the same with those of healthy volunteers on single administration. In long-term administration antidepressants have different effects in healthy and depressed subjects. In healthy volunteers cognitive effects of most compounds are normalized after the second week of treatment. However, attention and motor performances with amitriptyline are normalized after 3 weeks of treatment. Sedative motor or cognitive effects of imipramine do not exceed 8 days.(ABSTRACT TRUNCATED AT 400 WORDS)