Although men and women have a reportedly equivalent ratio of active epilepsy, men in particular are more likely to develop PTE (Yeh et al., 2012). PTE is a condition characterized by recurrent unprovoked seizures that occur 1 week or longer subsequent to a brain trauma. The incidence of PTE ranges widely, from 4 to 53 %, depending upon the severity of the injury, the age of the individual at the time of injury, and latency to examination post-injury (Frey, 2003). The critical determinant in the development of PTE is the severity of the brain trauma. Similarly, the severity of the traumatic brain injury rather than the presence or absence of epilepsy appears to be most influential in the development and extent of cognitive dysfunction. In other words, the more severe the brain injury, the greater the likelihood that neurocognitive deficits will be present, as indicated by changes in behavior (e.g., disinhibition, agitation, and aggression) and decreased cognitive efficiency (Luethcke, Bryan, Morrow, & Isler, 2011; Mazzini et al., 2003). It is hypothesized that men present with higher rates of posttraumatic epilepsy due to the fact that males tend to engage in risk-taking and physically perilous activities more often than women.

Sexual dysfunction due to mechanical or hormonal deficits can have a profound effect on QOL and psychological well-being, and can secondarily impact neuropsychological functioning. Although the majority of men with epilepsy are able to enjoy a healthy sex life, both seizures and anti-epileptic drugs (AEDs) can have unwanted effects on sexual health and performance. Approximately 20–50 % of men with epilepsy have sexual dysfunction, manifested as decreased libido, erectile dysfunction, or anorgasmia (Pack & Gidal, 2007). Specifically, sex drive may be diminished (Morrell, 1994), sexual performance may be impaired, and psychological issues can arise (such as the fear of having a seizure during sex) that impair sexual relations. In a recent study, men with epilepsy were more likely to report lower sexual desire and more erectile dysfunction than controls (Mölleken, Richter-Appelt, Stodieck, & Bengner, 2009). The cause of sexual dysfunction in these individuals is most likely multifactorial. However, it is primarily physiological, and physiological etiologies of sexual dysfunction can be broken down into two categories: physical and medication side effects (Kanner, Soto, & Gross-Kanner, 2000; Talbot, Sheldrick, Caswell, & Duncan, 2008).

Physical. Arousal and intimacy are complex phenomena that require a great deal of brain activity, both subtle and obvious. There are many vital parts of the brain involved in these behaviors. Seizures can interfere with portions of the brain that control sexual desire and performance and/or alter the delicate hormonal balance required for a healthy sex life (Olafsson, Hauser, & Gudmundsson, 1998; Schupf & Ottman, 1996). Sexual dysfunction in men with epilepsy is suspected at least in part to be associated with the effects of epileptogenic discharges in or adjacent to the limbic system/temporal lobe. An association between partial epilepsy and decreased sexual drive during the postictal period has been reported (Kanner et al., 2000). In a study by Morrell, Sperling, Stecker, and Dichter (1994), the authors determined that genital blood flow was diminished in men with temporal lobe epilepsy (TLE) compared to controls when viewing a sexually erotic movie.

Medication side effects. Talbot et al. (2008) found that individuals with epilepsy taking enzyme-inducing AEDs had lower levels of testosterone compared with those taking non-enzyme-inducing AEDs. Certain medications such as phenytoin and carbamazepine can alter the actions of various hormones, resulting in a decrease in sexual desire and performance. Older seizure medications, such as phenobarbital and primidone, can make it difficult to achieve an erection due to their effects on male hormones (Schupf & Ottman, 1996). The mechanism found in enzyme-inducing AEDs is an increased clearance of free testosterone with increased circulating levels of sex-hormone binding protein (an inactive hormonal component) (Smaldone, Sukkarieh, Reda, & Khan, 2004). Men taking phenytoin or phenobarbital may also develop Peyronie’s disease, which produces a painful, curved erection (although of note, while this problem has been associated with these medicines, it has not been definitively proven that they cause this condition). Fortunately, these side effects typically disappear when medications are changed.

Complaints of sexual dysfunction in men with epilepsy should be addressed with a thorough physical and neurological examination, and a possible referral for a urological evaluation. Treatments include sex education and behavioral therapy. Additionally, erectile dysfunction usually responds well to pharmacological intervention. Fortunately, sexual health can also, in some cases, be restored through hormonal treatments. For example, testosterone replacement can help reestablish a man’s libido and may also be helpful in improving depressed mood. Additionally, in some cases, sexual dysfunction disappears after successful epilepsy surgery (Cogen, Antunes, & Correll, 1979).

Seizures themselves, as well as interictal activity, can alter the level of hypothalamic and pituitary hormones, leading to changes in the secretion of gonadal steroids. Certain AEDs can also have an effect on hormonal levels. Thus, both the physiological effects of having epilepsy, and, medication-induced physiological changes, may potentially lead to changes in sexual functioning and other aspects of behavior. In men with epilepsy taking AEDs, baseline levels of luteinizing hormone (which stimulates the production of testosterone) may be lower than normal, with an exaggerated response to gonadotropin-releasing hormone (Dana-Haeri, Oxley, & Richens, 1984; Rodin, Subramanian, & Gilroy, 1984). There is also an interictal change in luteinizing hormone functioning, with a slower pulse rate (Morrell, 1994; Schupf & Ottman, 1996). Prolactin is elevated interictally in men with epilepsy (Levesque, Herzog, & Seibel, 1986; Rodin et al., 1984) and prolactin levels increase twofold after generalized convulsive seizures and after complex partial seizures involving limbic structures (Dana-Haeri, Trimble, & Oxley, 1983; Sperling, Pritchard, Engel, Daniel, & Sagel, 1986). However, whether there is a connection between changes in prolactin levels and hyposexuality is still unclear. There is also evidence of androgen deficiency in men with epilepsy. In men with epilepsy receiving cytochrome P450 (CYP) inducing AED’s, such as phenytoin, the synthesis of sex-hormone binding protein is induced, leading to a decrease in free fraction (active) testosterone levels (Beastall, Cowan, Gray, & Fogelman, 1985). Individuals receiving gabapentin and lamotrigine (which do not induce CYP) have levels of steroid hormones similar to controls. These observations suggest that changes in steroid hormones are due to medications and are not secondary to seizures or epilepsy (Morell et al., 2001).

From a neuropsychological perspective, some studies have shown that optimal levels of sex hormones are associated with better global cognitive scores (Hogervorst, Matthews, & Brayne, 2010). Particularly in men, low testosterone levels have been reported as a risk factor for cognitive decline and, some have speculated, the onset of dementia (LeBlanc et al., 2010; Moffat, 2005). However, other reports have not found cognitive deterioration to be associated with lower testosterone levels in the elderly (Holland, Bandelow, & Hogervorst, 2011).

Reduced fertility in men is thought to be due to disturbances in the pituitary gonadal hormones. However, most men with epilepsy are able to father children (Herzog, 2007). Men taking CYP-inducing AEDs have reduced levels of testosterone and are also at risk for impaired spermatogenesis (Herzog, 2007). One study showed that men with epilepsy had reduced seminal fluid volume, spermatozoa concentration, and total sperm count compared with control subjects (Taneja, Kucheria, Jain, & Maheshwari, 1994). Thus, while larger scale studies of each of these areas are needed, there is growing evidence to suggest that males with epilepsy are at greater risk not just for sexual dysfunction, but also fertility problems, when compared to their healthy peers. Possible contributing factors include, but are not limited to, the direct effects of epilepsy, medication side effects, and hormonal changes. Fortunately, some of these problems appear to be reversible with the proper treatment once detected by a physician (Brodie et al., 2013). Nonetheless, from an emotional and neuropsychological perspective, hormonal alterations, sexual dysfunction, and infertility/decreased fertility have the potential to secondarily impact functioning in these areas for men with epilepsy.

The understanding of language localization and functioning initially began over a century ago with observations of language deficits following stroke. Broca and Wernicke led the way, and through observation and pathological study, language was determined to be a left hemisphere function for most individuals, with different aspects of language positioned in different locations. Studies of individuals withepilepsy have provided additional understanding regarding the organization oflanguage functions, including language dominance (through intracarotid amobarbital testing) and neuroanatomical function of language centers of the brain (through cortical stimulation, functional neuroimaging, and surgical resection). Neuropsychological testing has provided additional functional understanding of language deficits in individuals with epilepsy. Gender-related differences within each of these areas have been reported.

Cerebral language organization and dominance. The cerebral hemispheres in humans are known to be asymmetrically organized. In the majority of right-handed individuals, verbal functions are supported by the left hemisphere, whereas nonverbal functions may be more right-hemisphere dependent (Milner, 1975). In some individuals, however, language is dependent on the right or both cerebral hemispheres. Evidence for such atypical language organization is far more commonly observed in left-handed or ambidextrous individuals (Trenerry, 1995). Data on potential gender-related differences in cerebral language dominance are inconclusive. It has been proposed by some that language is more strongly lateralized in males than females (Hampson, 1992; Kimura, 1999; Levy, 1972). The most convincing evidence supporting this hypothesis is that males have a higher incidence of aphasia following lesions to the left hemisphere (McGlone, 1977). However, consideration of the anatomical evidence suggests a rather different conclusion, as the male brain tends to be anatomically more symmetrical, while the female brain is more asymmetrical (usually in favor of the left side; Galaburda, Rosen, & Sherman, 1990; Geschwind & Galaburda, 1985). A meta-analysis utilizing functional neuroimaging with healthy men and women suggested no gender differences in cerebral dominance for language (Sommer, Aleman, Bouma, & Kahn, 2004).

In the epilepsy population, hemispheric language dominance presents an even more complex picture. Atypical (i.e., right-sided or bilateral) hemispheric language dominance is more frequent in individuals with epilepsy in comparison to the general healthy population (Springer et al., 1999). This is not unexpected given that, in many individuals with epilepsy, the cause of focal epilepsy is a structural abnormality which is often developmental or acquired during early childhood; a time when there is greater potential for neuronal plasticity, and thus, cerebral reorganization (Rasmussen & Milner, 1977; Springer et al., 1999). Brain abnormalities associated with epilepsy have the potential to interfere with the normal neuroanatomical organization of cognitive functions, even if the abnormality is far from the speech centers (Staudt et al., 2001).

The gold standard for evaluating cerebral language dominance involves temporary inactivation of the left/right hemisphere by intracarotid injection of amobarbital (IAT; Wada, 1949; Wada & Rasmussen, 2007). This procedure determines the functions of a single hemisphere, as well as deficits resulting from deactivation of the contralateral hemisphere. Given the invasiveness of the procedure, it is restricted to patients with planned resective surgeries in, or close to, eloquent brain areas (Hamberger & Walczak, 1995). Although the results from individuals with epilepsy cannot be generalized to a healthy population, examination of individuals who have undergone the IAT has provided some insight into gender differences in language dominance.

Strauss, Wada, and Goldwater (1992) examined 94 individuals with epilepsy who had undergone the IAT in order to determine whether gender affected the pattern of hemispheric reorganization following cerebral injury. The study showed no sex differences in the overall incidence of atypical language dominance in those with left hemisphere seizure involvement (i.e., unilateral left or bilateral foci). However, the period in which hemispheric reorganization for speech appeared to occur was much shorter in females than in males. That is, in females, reorganization was most likely to occur within the first year of life, while males appeared to have a longer window, which extended until puberty. The authors postulated several possible reasons for the observed gender differences, with one possibility being sex differences in rates of maturation. The maturation process proceeds more slowly in boys than girls, and therefore, the authors suggested the slower maturation of the male brain during childhood leaves the right hemisphere available over a longer period of time for the acquisition of speech/language functions (Conel, 1939).

While Strauss, Wada, and Goldwater (1992) described a gender difference with regard to the period during which reorganization of language is likely to occur, other studies have not found similar results with regard to age of onset of epilepsy. For instance, Helmstaedter, Brosch, Kurthen, and Elger (2004) observed that women with left hemisphere epilepsy were more likely to display atypical language dominance than men with left hemisphere epilepsy, but found no significant interaction between gender, age at onset of epilepsy, and language dominance. Upon closer review of Strauss, Wada, and Goldwater’s (1992) data, the authors noted that their results may have differed due to disparities in definitions of onset of dysfunction and different interpretations of atypical dominance in patients with right hemisphere epilepsy. Strauss, Wada, and Goldwater (1992) concluded that gender may affect plasticity for speech reorganization. If this were indeed the case, then more pronounced sex differences in patients might be expected with a functional disturbance affecting the original language-dominant hemisphere. However, Strauss, Wada, and Goldwater (1992) could not differentiate between the effects of functional disturbance of the dominant versus non-dominant hemisphere because patients with predominantly right hemisphere seizure involvement were not included in the sample.

Kurthen, Helmstaedter, Elger, and Linke (1997) evaluated sex-related differences in language dominance in a large sample of individuals with epilepsy with complex partial seizures. In this study, language dominance was considered a continuous variable based on comprehensive language testing during left- and right-sided IAT. The authors sought to determine whether: (a) there were sex differences in the mean degree of atypicality of language dominance in the total group, and (b) whether the side of major functional disturbance affected the occurrence and/or degree of sex differences in language dominance. The authors examined a sample of 267 individuals with complex partial epilepsy who underwent the IAT as part of a presurgical evaluation. They found a higher degree of atypicality in females in the total patient group, although the results were not significant. However, since it was assumed that language dominance would be affected by the epilepsy itself in all individuals with unilateral epileptic foci, the sample was separated and sex differences were examined with regard to left- and right-sided resection subgroups. The results demonstrated that females had a significantly higher degree of atypicality only in the left-sided resection group and that the correlation of age at onset of epilepsy and the degree of left hemisphere dominance was significantly positive for both males and females in the left-sided resection group, while there was a greater (albeit, non-significant) trend in the negative direction for females than males in the right-sided resection group. The authors concluded that gender differences in cerebral language dominance among individuals with epilepsy were detectable in the subgroup of those with left hemispheric resections, in which females were less strictly left hemisphere language dominant than males. They further suggest that females have a stronger disposition than males to develop atypical language dominance in the presence of left hemisphere impairment. Finally, they postulated that the fact that the sample of females with right hemisphere resection tended to be more atypically dominant with a later onset of epilepsy might imply a naturally higher tendency towards atypicality in females, but they acknowledged that there were limited data to support that hypothesis.

Thus, the data is inconsistent regarding whether cerebral language dominance is related to gender. While some of the studies described above found gender differences in cerebral language dominance in the epilepsy population, other studies have found no such differences. Some reports find that variables other than gender are more important. For example, in a functional MRI (fMRI) study comparing 100 healthy right-handed subjects to 50 right-handed individuals with epilepsy (Springer et al., 1999), atypical language dominance in the epilepsy group was associated with an earlier age of brain injury and weaker right hand dominance. However, language lateralization was not strongly related to gender, education, or task performance in the group with epilepsy. Janszky et al. (2003) investigated medial temporal lobe epilepsy (MTLE) due to unilateral hippocampal sclerosis. Using the IAT to determine language dominance, they found that atypical language dominance in left MTLE was associated with higher spiking frequency and with sensory auras representing an ictal involvement of the lateral temporal structures. Neither gender, nor age at epilepsy onset, nor age at initial precipitating injury was associated with atypical language dominance in left MTLE. The authors concluded that in individuals with focal epilepsy, the epileptic activity itself (i.e., interictal discharges and seizure spread) influenced speech reorganization.

The neuropsychology of language functioning in individuals with epilepsy. It has long been taught in developmental psychology classes that gender differences exist in cognitive functioning, with females having the advantage over males in a number of areas such as language abilities (Anastasi, 1958; Demo, 1982; Halpern, 1992; Maccoby, 1966; Maccoby & Jacklin, 1974). These initial conclusions were heavily drawn from normative data on aptitude measures, many of which were developed during the mid-twentieth century (Feingold, 1988). Greater rates of language-based reading disorders in boys than girls also supported this hypothesis (Flannery, Liederman, Daly, & Schultz, 2000) (see also D’Amatao and Wang in this volume). However, subsequent reviews of initial studies revealed discrepancies with regards to reported developmental timing of the onset of verbal differences, as well as which types of verbal abilities were stronger in females as compared to males. For instance, in the first meta-analysis of its kind in this area of research, Hyde and Linn (1988) reviewed 165 articles involving over 1,400,000 subjects in an attempt to statistically delineate gender differences in language functioning. Their findings indicated a gender difference favoring verbal ability in females of approximately one-tenth of a standard deviation, one they interpreted as “scarcely” warranting attention in “theory, research, or textbooks.” Further, there was no significant difference between the genders with regard to the types of verbal ability (e.g., vocabulary, reading comprehension, verbal reasoning), as some authors had previously declared.

Nonetheless, some authors have continued to cite differential gender findings and a possible explanation for this has been provided by Ullman, Miranda, and Travers (2007), who suggested that they might be related to the stronger declarative memory of females when compared with that of males. According to these authors, this difference might allow females to better function on some language tasks. In epilepsy research, two diverse patterns appear in the literature, with one suggesting that no gender differences are found among the neuropsychology of language functioning, and the other revealing that men outperform women on language measures. Martin, Loring, Meador, and Lee (1990) studied verbal fluency among individuals with unilateral TLE and found no gender differences. However, Baxendale, Heaney, Thompson, and Duncan (2010) found that in childhood-onset TLE, gender effects were seen for verbal IQ and conformation naming, such that male subjects outperformed female subjects. No other cognitive measures differed by gender. Randolph, Lansing, Ivnik, Cullum, and Hermann (1999) also found that men with TLE outperformed women with TLE on a visual confrontation naming test; which they determined was related to the preponderance of male-biased items.

Cortical stimulation, functional neuroimaging, and surgical resection. In addition to the IAT, electrographic stimulation of cortex on and around the proposed surgical site in a patient who is a candidate for surgical resection for the treatment of medically refractory epilepsy has been helpful in understanding language localization in this particular population (e.g., Zhang et al., 2013). Mateer et al. (1982) found a higher proportion of naming sites in the anterior temporal cortex in males than females utilizing cortical stimulation mapping. Another study by Ojemann, Ojemann, Lettich, and Berger (1989) revealed that males were more likely than females to have naming errors arising from the parietal lobe. Further, of the small subgroup in which this pattern existed, they found that females were more likely than males to have language represented only in the frontal lobes. On the other hand, Devinsky et al. (2000) and Schwartz, Devinsky, Doyle, and Perrine (1998) found no such gender differences.

A meta-analysis of fMRI research did not support the presence of a gender difference in cerebral dominance for language (Frings et al., 2006). However, there is some evidence for gender-related differences in the utilization of language when undergoing memory tasks. Frings et al. (2006) found that in an approach to a spatial memory task, men estimated that their strategy was significantly more nonverbal than did women. This finding might have important clinical ramifications, such that for a non-dominant temporal lobe resection, women might fare better cognitively than men, as they tend to use left-lateralized activation patterns and employ more verbal strategies during spatial memory tasks than do men. Literature regarding language functioning and gender differences post surgical resection of epileptogenic tissue is largely lacking. There is a known link regarding impairment of visual confrontation naming ability following dominant temporal lobe resection postoperatively on neuropsychological measures (Busch, Frazier, Haggerty, & Kubu, 2005; Chelune, Naugle, Lüders, & Awad, 1991; Davies, Bell, Bush, & Wyler, 1998; Hermann, Seidenberg, Schoenfeld, & Davies, 1997). However, there either does not appear to be any difference in gender postoperatively related to the type and location of surgery performed, or postsurgical language outcomes related to gender effects are not delineated in the research to date.

In summary, while language lateralization per se may not differ in male versus female patients with epilepsy, data do suggest that the period in which hemispheric reorganization for speech occurs is much shorter in females than in males. With regard to language functions, contrary to earlier beliefs that females tended to demonstrate stronger verbal abilities, research in the area of epilepsy has generally not supported this view. However, there may be some evidence for gender-related differences in utilization of language when undergoing memory tasks that could have clinical ramifications in individuals with epilepsy who undergo non-dominant hemisphere surgery (Frings et al., 2006).

Research among individuals with epilepsy has also contributed to our understanding of sex differences in terms of memory functions, as well as possible psychological processes or even physiological variables underlying these differences. As noted previously, some studies find that females tend to do better than males on tests of verbal abilities, whereas males tend to do better than females on measures of arithmetic and spatial abilities (Estes, 1974; Maccoby & Jacklin, 1974; Mann, Sasanuma, Sakuma, & Masaki, 1990; McGlone, 1978; Oerzel, 1966; Weinderholt et al., 1993). Research among the normal population has also found gender differences for memory. Using memory tasks involving words, pictures, and designs, Hart and O’Shanick (1993) found that neurologically intact females performed better on verbal memory measures than on visual memory measures. For males on the other hand, the opposite pattern was found. List learning studies have been particularly consistent in terms of women’s superiority for verbal memory (Ganung, 1972). Ganung (1972) found female superiority on a serial list learning task and male superiority on a spatial memory task. Bolla-Wilson and Bleecker (1986) also found female superiority on all learning trials of the Rey Auditory Learning Test. Wiederholt et al. (1993) determined that women performed better than men on the Buschke Selective Reminding Test, another task of verbal memory. In addition, Kramer, Delis, Kaplan, O’Donnell, and Prifitera (1997) examined boys and girls 5–16 years of age without epilepsy and found that girls performed better on the five learning trials and delayed free recall trials of the California Verbal Learning Test for Children (CVLT-C). Other studies have also demonstrated consistent female superiority on verbal memory tasks such as word list or paired word associate tasks (Berenbaum, Baxter, Seidenberg, & Hermann, 1997; Kramer, Delis, & Daniel, 1988; McClone, 1994). Some have found female superiority on the Weschler Memory Scale (WMS), particularly on the Logical Memory and Paired Associates subtests (Ivison, 1977; Verhoff, Kaplan, & Albert, 1979). Other studies have also shown male advantage for visuospatial memory (e.g., performance on the RCFT) (Herlitz, Airaksinen, & Nordstrom, 1999; Lewin, Wolgers, & Herlitz, 2001). Yet other research has demonstrated female superiority for aspects of both verbal memory (word recall/recognition, object recall, and story recall) and visual memory (object locations and face recognition) (Bleecker, Bolla-Wilson, Agnew, & Meyers, 1988; Chipman & Kimura, 1998; Duff & Hampson, 2001; Hassan & Rahman, 2007; Postma, Izendoorn, & De Haan, 1998; Ragland, Coleman, Gur, Glahn, & Gur, 2000). Perhaps not surprisingly, similar findings have been reported in terms of memory among individuals with epilepsy. Research in epilepsy has shown that women with left TLE also have an advantage over men on verbal memory tasks (Berenbaum et al., 1997; Helmstaedter et al., 2004). Moreover, Berenbaum et al. (1997) determined that women were able to recall more words than men on the California Verbal Learning Test (CVLT), a list learning task, before and after surgery, regardless of extent of hippocampal damage. Baxendale et al. (2010) found that females with a history of MTLE outperformed males on a story recall task (on the Adult Memory & Information Processing Battery; AMIPB). Smith, Elliott, and Naguiat (2009) also looked at gender differences among children and adolescents with a history of intractable epilepsy and found that girls performed better than boys on delayed story recall and learning of word lists.

In contrast to studies involving the left temporal area and verbal memory, results of research on sex differences regarding the right temporal area and visual memory utilizing epilepsy samples have been inconsistent (Helmstaedter et al., 2004; Strauss, Hunter, & Wada, 1995; Trenerry et al., 1996). More specifically, figural recall studies have been more discrepant. This inconsistency is also observed in non-clinical populations. In a study with normal subjects ages 55 and older, Wiederholt et al. (1993) determined that males performed better than females on the Visual Reproduction Test. In a study with individuals with epilepsy using the Benton Visual Retention Test, Helmstaedter (2004) found women’s performance to be lower than that of men. In contrast, Smith et al. (2009) studied children and adolescents with a history of intractable epilepsy and did not find any male advantage over females on the RCFT delayed recall trial. Conversely, Baxendale et al. (2010) found that females with a history of MTLE outperformed males on the design learning and complex figure recall tasks of the AMIPB, although not at a level of significance. Facial recognition studies have also been inconsistent. Bengner et al. (2006) found female superiority for delayed recognition of faces, regardless of epilepsy laterality. However, Smith et al. (2009) did not find any gender differences on visual memory tasks involving delayed facial recognition, among children and adolescents with epilepsy. The inconsistency and in some cases lack of difference between groups have been suggested to be possibly related to a confounding effect of using verbal encoding techniques during certain visual memory tasks (Helmstaedter, Pohl, & Elger, 1995). That is, certain visual memory tasks may not be as purely visual as they were designed to be.

Research has also focused on post-surgical gender differences in memory. Some studies have suggested that men and women differ in terms of the risks of memory decline following anterior temporal lobectomy (Bengtson et al., 2000). McMillan, Powell, Janota, and Polkey (1987) found a tendency for men to experience decline in verbal memory following left anterior temporal lobectomy and women to demonstrate significant visual memory decline following right temporal lobectomy. Similarly, Geckler, Chelune, Trenerry, and Ivnik (1993) found that following left anterior temporal lobectomy, women demonstrated greater performance on measures of verbal memory than men. Consistent with this, Trenerry, Jack, Cascino, Sharbrough, and Ivnik (1995) found that following left anterior temporal lobectomy, females demonstrated an improvement in story recall whereas men demonstrated signs of decline. Bengston et al. (2000) found that regardless of side of surgery, females demonstrated better memory performance than males following surgery on the WMS Logical Memory task, although the difference was modest and both groups demonstrated small performance improvements.

Helmstaedter et al. (2004)) examined the relationship between atypical dominance among men and women and memory function. They found that post surgery, women with atypical language dominance and LTLE showed better preserved verbal memory function (using the RAVLT) than women with left hemisphere language dominance and LTLE, men with atypical language dominance and LTLE, and men with left hemisphere language dominance and LTLE (a finding also seen in Helmstaedter, 2004). In fact, women’s verbal memory was largely unimpaired and within normal expectations. However, they also found poor figural memory performance for women using a task requiring repetitive learning and immediate reproduction of a set of nine abstract designs over six learning trials. Post surgery, figural memory did not change for left hemisphere dominant men; they showed no signs of impairment. However those men with atypical dominance showed a significant decline. Women with atypical dominance showed improvement. Those with left hemisphere dominance showed slight worsening. This mirrors previous findings of greater verbal memory for women and greater visual memory for men.

Other research on memory and gender among those with epilepsy has factored age and development into an understanding of sex differences. Some research has examined possible maturation issues. Strauss, Wada, and Hunter (1992) examined the possibility of greater vulnerability among boys for early cerebral damage. The authors looked at a sample of individuals with epilepsy in their 20s with a history of left hemisphere dysfunction early in life (before 1 year of age), with both typical and atypical language dominance. The authors found that males with atypical speech did not differ from those with typical speech on any given memory tasks (which included the WMS Logical Memory and Visual Reproduction tasks). Among females, significant differences were noted on all of the memory tasks. A relatively small follow-up study noted that those with later lesions tended to perform better than those with early damage, on all given tasks, including the above mentioned memory tasks. Kramer et al. (1997) examined whether sex differences in boys and girls change as a function of age or environmental factors and found an age effect for recall, recognition, semantic clustering, serial position effects, and errors on the CVLT-C, with the younger children most different from the older children. While they did not find a sex by age group interaction, as girls tended to outperform boys in numerous test variables, a trend was noted for increase in the size of sex difference for total recall, with age group, suggesting an increase in gender differences for verbal memory over time.

Certain research has determined greater decline among men with epilepsy on memory tasks. Bleecker et al. (1988) examined age-related changes for verbal memory for women and men, ages 40–89, using the RAVLT. The authors found a significant age-related decrease in performance on all of the learning trials of the RAVLT. It was also found that women consistently had higher scores for each trial over age, and the differences increased with age. Wiederholt et al. (1993) studied subjects age 55 and older and found that performance on the Selective Reminding Test and the Visual Reproduction Test decreased progressively from the youngest to the oldest age group (55–64, 65–74, 74–84, and 85 and older). The authors also found that men declined more rapidly than women on these tests.

Theories behind the observed sex differences have covered a number of different areas including genetics, hormones, neuroanatomical differences, and environmental factors. Specific research into the reasons for female superiority on verbal tasks has been conducted. Bolla-Wilson and Bleecker (1986) suggested that women do better on verbal learning tasks because of different or more verbally mediated strategy use. Sherman (1974) suggested that girls’ earlier development of language abilities orients them towards verbal problem solving strategies. Similarly, when Cox and Waters (1986) found a developmental lag for males in the initial use and subsequent generalization of organizational strategies (i.e., among elementary school children, girls were more likely than boys to use a semantic organization strategy during a list recall task), they suggested that female semantic development might proceed at a faster pace than males’ and that a more elaborate semantic network therefore encouraged the use of organizational strategies during memory tasks. Kramer et al. (1988) examined differences in neurologically intact males versus females on performance on the CVLT and found greater use of semantic clustering in females. For males, these authors found a greater use of serial clustering, which is deemed to be a less effective and efficient strategy. Kramer et al. (1997) also found that girls were more likely than boys to use a semantic clustering strategy. Therefore, females’ greater use of such strategies may be the result of increased time and hence familiarity in using such, as compared to males. For those tasks for which semantic clustering would not provide clear benefit, it is possible that other more efficient encoding strategies, such as elaboration, imagery, and depth of semantic processing might also be used more often by women (Berenbaum et al., 1997).

Early on, O’Connor (1943) suggested that genetic factors might be involved in sex differences in cognition, given the finding that 25 % of observed females scored above the median for males on a spatial ability test. Stafford (1961) suggested that aptitude for spatial visualization had a hereditary component transmitted by a sex-linked recessive gene, a possibility also raised in other studies (Bock & Kolakowski, 1973; Yen, 1975). However, this has not been a consistent finding, particularly in studies with larger sample sizes (DeFries, Vandenberg, & McClearn, 1976). Other research has linked hormones with levels of intelligence and spatial ability (Broverman, Klaiber, Kobayashi, & Vogel, 1969); however, this connection has also been criticized and not well-replicated (Klaiber, Broverman, Gogel, Abraham, & Cone, 1971; Klaiber, Broverman, & Kobayashi, 1967; Parlee, 1972; Singer & Montgomery, 1969). Geschwind and Galaburda (1985) suggested that testosterone slows the development of the left hemisphere and Kramer et al. (1997) suggested that higher levels of prenatal testosterone in males result in the right hemisphere being more developmentally advanced than the left, and in turn accounts for male superiority in some spatial skills and a female superiority for some verbal skills.