RELATION BETWEEN COGNITIVE DYSFUNCTION AND PSEUDOBULBAR PALSY IN AMYOTROPHIC-LATERAL-SCLEROSIS

Objectives-To examine the relation between cognitive dysfunction and p seudobulbar features in patients with amyotrophic lateral sclerosis (A LS). Methods-The performance of two patient groups, ALS with pseudobul bar palsy (n = 24) and ALS without pseudobulbar palsy (n = 28), was co mpared with 28 healthy age matched controls on an extensive neuropsych ological battery. Tests used were the national adult reading test, sho rt form of the WAIS-R, recognition memory rest, Kendrick object learni ng test, paired associate learning, Wisconsin card sorting test, verba l fluency, Stroop and negative priming tests, a random movement joysti ck test, and a computerised Tower of Hanoi test. Results-Tests of exec utive function showed a pronounced deficit on written verbal fluency i n both ALS groups in comparison to controls, which tended to be more p rominent in patients with ALS with pseudobulbar palsy. The random move ment joystick test (a non-verbal test of intrinsic movement generation ) showed an impairment in the generation of random sequences in patien ts with pseudobulbar palsy only. The computerised Tower of Hanoi showe d a subtle planning impairment (shorter planning times) in all the pat ients with ALS compared with controls on trials requiring more complex solutions. In addition the pseudobulbar patients displayed shorter pl anning times on complex trials, and tended to solve these trials less accurately. There was also evidence of a deficit for all patients with ALS in comparison with controls on total errors and number of categor ies achieved on the Wisconsin card sorting test and a strong tendency towards an impairment on a task of selective attention and cognitive i nhibition (negative priming). A word recognition memory deficit was sh owed across both ALS groups. Conclusions-This study elicited cognitive deficits (involving predominantly executive processes, with some evid ence of memory impairment) in patients with ALS and further strengthen ed the link between ALS and frontal lobe dysfunction, this being more prominent in patients with pseudobulbar palsy, However, cognitive impa irments suggestive of extramotor cortical involvment were not exclusiv e to this subgroup.