Computerized Finger Tapping Task in Adult Unipolar Depressed Patients and Healthy Subjects : Influence of Age , Gender , Education , and Hand Dominance

Introduction: Current diagnostic criteria for depression include psychomotor retardation, being the Finger Tapping Test (FTT) as one of the most utilized instruments to assess fine psychomotor performance. Method: This study aimed to compare the performance of a sample of 51 unipolar depressed patients (30 women and 21 men, with a mean age of 45.12 years old [SD = 14.09]) with 51 healthy controls (29 women and 22 men, with a mean age of 44.49 years old [SD = 15.59]) in a computerized version of the Finger Tapping Test (FTT) from the Psychology Experiment Building Language (PEBL). Another objective was to test this version’s validity in comparison to other FTTs. Results: We found significant differences between depressed patients and healthy controls. Significant effects of age and gender were found. Conclusion: Results allowed us to identify differences in performance between the two groups, therefore this version of the FTT revealed adequate reliability values, one instrument accessible to all clinicians.

The original manual of the FTT utilized a mechanical counter and a stopwatch (Christianson & Leathem, 2004): many limitations were pointed out, as it could take several hours, needing additional time for scoring and presenting results, and was exhausting for patients and too laborious for examiners (Hubel et al., 2013a).However, its efficacy still justifies its place among the most used instruments (Strauss et al., 2006).Therefore, recently, in an attempt to overcome such limitations, several computerized versions have emerged, which are able to measure the response time more precisely, requiring less time to administer, and generating instant scoring (Wilken et al., 2003).The FTT is now part of several recent batteries, such as the Computerized Neurocognitive Battery (Coleman, Moberg, Ragland, & Gur, 1997;Gur et al., 2010), the Automated Neuropsychological Assessment Metrics-ANAM 4tm (Kane et al., 2007;Reeves, Winter, Bleiberg, & Kane, 2007;Wilken et al., 2003), the FePsy (Aldenkamp et al., 2002;Stewart et al., 2006), and the Neurotrax TM Mindstreams TM (Dwolatzky et al., 2003(Dwolatzky et al., , 2004;;Schweiger et al., 2003).
Our aim was to study the fine psychomotor performance of depressed patients, regarding effects of age, gender, education, and hand dominance.A computerized version of the FTT from the Psychology Experiment Building Language (PEBL) (Mueller, 2013), a free access battery, was used.Another objective was to test this version's validity, comparing our results to others obtained by Christianson and Leathem (2004) and Hubel and colleagues (2013b).
According to the literature, in FTT men tap faster, younger subjects show faster tapping rates; education is related to faster motor speed, and the dominant hand performs better.Our research hypotheses are based upon these premises, as well as in the prediction that depressed patients are slower than healthy controls.

Participants
Both studied samples, experimental and control groups, were comprised of 51 subjects each.The experimental (patients') group was composed of 30 women and 21 men, with a mean age of 45.12 years old (SD = 14.09), and a mean of 8.29 (SD = 3.72) years of education.The participants from this group were recruited in the city of Faro (Portugal), more precisely from the Department of Psychiatry and Mental Health of Hospital Center of Algarve (a state owned entity).With analogous characteristics, healthy controls comprised 29 women and 22 men, with a mean age of 44.49 years old (SD = 15.59), and a mean of 9.50 (SD = 3.63) years of education.Patients and controls did not differ significantly regarding gender (χ 2 = .040,df = 1, p = .841),age (t = .213,df = 100, p = .832,d = .042),and education (t = -1.668,df = 100, p = .099,d = -.330).In respect to gender, there are no differences in age in the patients group (t = -.816,df = 49, p = .419,d = -.225) and in the healthy controls group (t = .627,df = 49, p = .534,d = .172).
Statistically, participants were divided into three age groups: (a) 17-40; (b) 41-50; and (c) more than 51 years old.Regarding education, participants were also divided into three groups: (a) up to 6 years of education; (b) 9 years of education; and (c) 12 or more years of education.We only considered the completed cycles of education (i.e., 4 th grade, 6 th grade, 9 th grade, 12 th grade, and university), but then, only three groups were considered, since there were very few elements with 4 years of education, as well as with higher education.All participants were Caucasians and Portuguese speakers.

Measures
The computerized Finger Taping Task (Mueller, 2013), a free software from PEBL Test Battery (Mueller & Piper, 2014), was performed with the left and right index fingers: five consecutive trials in each hand, with a brief rest following each trial (10-seconds), and a longer one (30-seconds) every five trials.The mean of taps was averaged over five trials for each hand.

Procedures
Each participant completed a health and demographic questionnaire and depression diagnoses were confirmed through the MINI (Mini International Neuropsychiatric Interview) (Sheehan et al., 1997) and the BSI (Brief Symptom Inventory) (Canavarro, 2007).Those with current or prior history of bipolar disorders, schizophrenia, major psychosis, or who met criteria for dementia, substance abuse, neurologic disease, including head injury involving a loss of consciousness, and subjects who did not complete the full 50-second tapping period for both fingers or reported having a problem with their hands or indicators were excluded.To discard malingering, Rey 15-Item Memory Test (15-IMT) was used (Simões et al., 2010).
This study was approved by the Hospital Center of Algarve Ethics Committee, in conformity with the Helsinki declaration.After being provided with all the information about the study, all the participants signed an informed consent statement.
All analyzes were conducted using the Statistical Package for the Social Sciences (SPSS) version 20.0.The level of significance was set at p ˂ .05.

Results
We confirmed effects of slowing over in depressed patients, and, for both groups, significant effects of hand dominance (faster tapping in the dominant hand), gender (faster tapping in men), and age (slower tapping on participants over 51 years old).
Results showed statistically differences between total scores for depressed subjects and healthy controls, concerning both dominant (D) (t = -4.040,df = 100, p = .001,d = -.800) and Non-Dominant  Christianson and Leathem (2004) compared four versions of the FTT, involving minor differences in procedures and response devices, namely the Halstead-Reitan manual FTT (Halstead, 1947), the Massey University manual FTT, the Western Psychological Services Digital FTT, and a Computer FTT, having verified high correlations between the tapping scores of all four instruments, confirming the construct validity of the latter.Likewise, Hubel and colleagues (2013b) tested the validity of a novel FTT from the California Cognitive Assessment Battery (CCAB), obtaining analogous results through the comparison to the Halstead-Retain FTT, the Computerized Finger Tapping, the T3 Computer-assisted Finger Tapping Task, the Western Psychological Services Electronic Tapping Test, and the Computerized Neurocognitive Scanning Vital Signs (CNSVS).
The FTT has been reported to be sensitive to changes related to aging (Ylikoski et al., 1998).Better performance is usually associated with younger age, as many studies have shown older subjects tend to have significantly slower tapping rates (Aoki & Fukuoka, 2010;Ashendorf et al., 2009;Bartzokis et al., 2010;Bornstein, 1985;Elias et al., 1993;Gur et al., 2010;Hubel et al., 2013aHubel et al., , 2013b;;Ruff & Parker, 1993;Shimoyama et al., 1990;Turgeon, Wing, & Taylor, 2011;Ylikoski et al., 1998).To Bartzokis and colleagues (2010), age-related trajectory of finger tapping speed can be associated with brain myelin integrity, reaching its peak in mid-life and declining in older age, eventually leading to psychomotor slowing.Heaton and colleagues (2004) reported in their large normative sample (aged 20-85 years) that about 16% to 18% of the variance in finger tapping scores was accounted for by age.We also verified age-related effects, with older subjects performing poorly, with variance in the scores between 14% to 24% in both samples (depression and healthy groups).
We noticed effects of education on tapping speed.Nevertheless, according to Strauss and colleagues (2006), results on motor tasks have a propensity to be very modestly influenced, if at all, by such factors.Heaton and colleagues (2004) verified that education accounts for only about 2% to 4% of the variance in tapping scores.
Still, as reported by other studies, best performances are often associated with more years of education, concerning not only higher levels of formal instruction (Ashendorf et al., 2009;Bornstein, 1985;Gur et al., 2010;Ruff & Parker, 1993), but also parental education (Gur et al., 2010).
Also comma as expected (Bashir et al., 2013;Hill et al., 2004;Hueng et al., 2011;Kertzman et al., 2010;Lampe et al., 2004;Rohling et al., 2002;Swann et al., 1999), we found significant impairment in psychomotor speed between unipolar depressed subjects and controls.Psychomotor performance in depressed subjects may be further influenced by other factors, such as hospitalization status/duration, severity, subtype and duration of depression, and medication (Bashir et al., 2013).Many studies have addressed specifically effects of medication on psychomotor speed (Aldenkamp et al., 2002;Bashir et al., 2013;Stewart et al., 2006).First-line medication for depression often includes substances (e.g., fluoxetine, venlafaxine, and paroxetine) liable to affect cognitive and function performance (Bashir et al., 2013).Bashir and colleagues (2013) verified a significant speed impairment regarding patients on antidepressants.Therefore, there are researchers (e.g., Hueng et al., 2011;Meyer et al., 2006;Swann et al., 1999) who chose to study only drug-free depressive subjects to access more precisely the actual impact of the illness itself on psychomotor function.This may represent a limitation to our study, but, for ethical reasons, we could not assess the clinical sample of medications.
In order to share these initial data, we present a percentile tables of the present sample, healthy subjects (Table 4) and depressive subjects (Table 5).

Table 3 .
Comparison of the FTT from PEBL to other tapping test data a n = 51, b n = 86, c n = 1.519, d 1 st 10-sec.average.

Table 4 .
Percentile of healthy subjects by age and gender

Table 5 .
Percentile of depressed subjects by age and gender